Widely tunable lasers are generally considered as the transmitters of future WDM optical communications. Electronically tunable edge-emitting laser diodes are of particular interest as they can switch the wavelength in tens of nanoseconds and thus offer great potential for new networking concepts such as optical packet or burst switching, label switching, bandwidth on demand, ... In this paper we discuss new concepts for such widely tunable laser diodes which are studied in the framework of the European IST project NEWTON (NEw Widely Tunable laser diodes for Optical Networks).

We achieved first dynamic all-optical wavelength conversion in bandgap-engineered MZI SOA all-optical switch. Clear eye-diagram of 2.5Gbps wavelength conversion was confirmed. This is the first wavelength conversion demonstration with a bandgap-engineered PIC with either selective-area-growth and quantum-well-intermixing techniques.

In this paper, a comprehensive broad-band model of tunable wavelength converter based on four-wave mixing (FWM) in semiconductor fiber ring laser (SFRL) is presented. Critical factors, eg., the material gain profile, the longitudinal variation of the optical field, the carrier density and the broad-band spontaneous noise emission are considered in the model. By numerical simulation, the effects of the input signal power, injection current, the coupling of the output couplers and the lasing wavelength on the performances of the wavelength converter, such as the conversion efficiency and the SBR, are investigated. Simulation results are in agreement with the experimental results in literatures.

Tunable four-wave mixing (FWM) wavelength conversion based on semiconductor optical amplifier (SOA)-based fiber ring laser is analyzed theoretically and experimentally. Theoretical models for SOA-based fiber ring laser and FWM wavelength conversion are established. Output characteristics of SOA fiber ring laser with input signal and without input signal, and conversion efficiency versus wavelength shift are experimental measured and theoretical calculated, experimental results are coincidence with theoretical simulated results finely. Tunable wavelength conversion at 10Gb/s with 32nm tuning range is demonstrated. Results show that the exploitation of erbium-doped fiber amplifier (EDFA) in fiber ring laser is helpful for tuning range widening and input dynamic range increasing.

Two approaches to realize the VCSEL devices based on GaAs substrates are investigated. The first approach utilizes InGaAs quantum wells with dilute nitride to extend the bandgap toward long wavelenegth. The second approach utilizes InAs/InGaAs quantum dots based on Stranski and Krastanov growth mode with confinement and strain combined to adjust the bandgap to 1.3 μm wavelength. High quality epitaxial layers with low threshold have been achieved with MBE and MOCVD. VCSEL performances that have been achieved are: Multimode operation at 1.303 μm with slope efficiency of 0.15 W/A (0.2 W/A), and maximum power of 1 mW (4 mW) for room temperature CW (pulse) operation have been achieved with MBE-grown In GaAaN active regions. Room temperature, CW single mode operation with SMSR > 40 dB at 1.303 μm has also been achieved with a slope efficiency of 0.17 W/A and maximum power of 0.75 mW also with MBE-grown InGaAaN active regions. In addition, MOCVD grown has also achieved a performance at 1.29 μm with slope efficiency, 0.066 W/A, and maximum power, 0.55 mW. VCSELs with 9 layers of quantum dots and all-semiconductor DBRs also achieved lasing at 1.3 μm.

In this paper, we demonstrate high performance 850 nm InGaAsP/InGaP strain-compensated MQWs vertical-cavity surface-emitting lasers (VCSELs). These VCSELs exhibit superior performance with threshold currents of ~0.4 mA, and slope efficiencies of ~ 0.6 mW/mA. High modulation bandwidth of 14.5 GHz and modulation current efficiency factor of 11.6 GHz/(mA)^1/2 are demonstrated. We have accumulated life test data up to 1000 hours at 70°C/8mA. In addition, we also report a high speed planarized 850nm oxide-implanted VCSELs process that does not require semi-insulating substrates, polyimide planarization process, or very small pad areas, therefore very promising in mass manufacture.

The light intensity response and the transfer function of laser are given in small signal in order invest the upper modulation frequency of VCSELs. The cures of the relaxation oscillation frequency and -3dB bandwidth versus the differential gain coefficient and the spontaneous emission lifetime are presented. The results show that the high speed modulation characteristics can be achieved by increasing the differential gain. We also find out the modulation frequency of VCSELs is improved by decreasing carrier lifetime in the quantum well VCSELs. The spontaneous emission lifetime versus the cavity length is also presented due to the micro-cavity effect. The ultimate limit of direct modulation bandwidth in VCSELs is explored. A new scheme to increase the modulation bandwidth is proposed.

Anti-resonant reflecting photonic crystal structure is employed in vertical cavity surface emitting lasers (VCSELs) to achieve photon confinement in lateral direction. Such a design is promising in supporting large aperture single-mode emission. In the configuration, a hexagonal array of high-index cylinders which run vertically in the cladding region are introduced in the top of the VCSEL p-type DBR mirror region. The transverse modal property of the proposed structure, especially leakage loss, has been investigated. An optimum design for the minimum radiation loss while maintaining single-mode operation has been discussed in this paper.

The temperature characteristics of Oxide-confined VCSEL are described, these records of high operating temperature are caused by high characteristic temperature. The VCSEL device temperature is increased by heating from ambient temperature 20°C up to 100°C. The effect of temperature elevation increased from T₁ to T₂ on the threshold current I_th(T) is often described by a characteristic temperature. We obtain a function T₀(T) which decreases from 220K at 20°C temperature to 200K at 100°C. The essential improvements for the oxide-confined VCSEL in this work are focused on the following two points. First, we decrease the series resistance of the VCSEL. Secondly, the oxide-confined technique reduces defects and optical absorption in the active region. The oxide-confined is worthy to be used just because of its better confinements for both beam and current, easier processing, and lower cost. The fact that the device’s threshold current in pulse operation slightly depends on ambient temperature means that the VCSEL’s characteristic temperature (T₀) is higher.

The wide tunability and the dynamic properties of the SG-DBR have been simulated using a numerical time-domain dynamic model. The experimental results of the SG-DBR tuning map and mode stable characteristic have been investigated.

In this paper, a simple novel all-optical exclusive OR (XOR) logic gate architecture based on Sagnac interferometric loop mirror is proposed for the first time. Using Semiconductor Optical Amplifier (SOA) as nonlinear medium, and through numerical analysis, this scheme is proved to exceed the operation speed limit due to the limited carrier recovery time of the SOA. In order to optimize the operation performance of the proposed XOR logic scheme, the SOA parameters and the signal parameters are discussed. The operation of this scheme with 80Gb/s RZ pseudorandom bit sequences (PRBS) is simulated with fairly high performance.

Compositional distribution of the quantum well and barrier after quantum well intermixing for GaInP/AlGaInP system was theoretically analyzed on the basis of atom diffusion law. With the compositional distribution result, the valence subband structure of the intermixed quantum well was calculated on the basis of 6×6 Luttinger-Kohn Hamiltonian, including spin-orbit splitting effects. To get more accurate results in the calculation, a full 6-band problem was solved without axial approximation, which had been widely used in the Luttinger-Kohn model to simplify the computational efforts, since there was a strong warping in the GaInP valence band. At last, the bandgap energy of the intermixed quantum well was obtained and the calculation result is of much importance in the analysis of quantum well intermixing experiments.

We present a three dimensional photonic crystal structure capable of being used as light sources in quantum information system. The band structure and defect mode properties are given. A stochastic method is employed to study the dynamics of the system. Strong Purcell effect is expected to be observed in this structure, which make it an efficient light emitter in quantum information applications.

All-optical wavelength converter is demonstrated by using a SOA-based fiber ring laser and an asymmetric Mach-Zehnder interferometer (AMZI). There is no need for an additive probe beam source in this configuration and the output beam from the fiber ring laser will be utilized as the probe beam to complete a wavelength conversion. The operation principles of the all-optical wavelength conversion with the proposed configuration are analyzed theoretically. In this analytical process the steady-state and gain-modulated oscillations of the fiber ring laser with and without the input signal beam are described, respectively. Also the operation principle of the AMZI to convert a phase-modulated signal into an intensity-modulated one is introduced. An experimental system and its performances as well as some measured results, such as time waveforms, extinction ratios and bit-error rates, are demonstrated. Some discussions also are given.

Nonlinear Optical Loop Mirror (NOLM) is a very popular optical fiber device. When it’s inserted semiconductor optical amplifier (SOA), a lot of use it can be provided with. This work assesses the prospects for high-speed all optical wavelength conversion using semiconductor optical amplifiers inserted in NOLM based on cross-phase modulation (XPM) in a SOA and interference in Sagnac Interferometer. In this paper, we analyzed of parameters optimization for XPM wavelength conversion in the structure mentioned above, Segmented model for SOA, additional continuous control pulse are exploited in the theoretical analysis. The influence of an additional input light on converted waveform is shown. The output power and extinction ration changing with signal wavelength and input power are introduced.

An injection locked semiconductor lasers is a promising low cost alternative to implement an all-optical wavelength conversion. We demonstrate high speed wavelength conversion in this paper by injecting dual wavelength laser into a laser diode. The 10Gb/s inverting and non-inverting conversions are obtained in experiments. 30nm conversion range is also achieved.

We theoretically report a new method to achieve variable-in, variable-out wavelength conversion in LiNbO₃ with aperiodic optical superlattices (AOS) structure. The optimal structure of the LiNbO₃ sample was obtained through simulated annealing (SA) method. About 3.4nm prescribe pump bandwidth at 1559nm is achieved to fulfill variable wavelength conversion among four selected ITU signal channels (C23-C20). As the result of large pump bandwidth, the reduced effective nonlinear coefficient of the AOS sample decreases to 0.21. Fluctuation of the operation temperature, variation of the incident angle and the errors in poling process show little influence on the performance of the device.

Organic light emitting diodes (OLED) employing an Ir complex with coumarin (C6) and acetylacetone (acac) ligands Ir(C6)₂(acac) are studied. This novel Ir complex can be used both as electron transporting material and light emitting dopant. From a calculation, the PL quantum efficiency of Ir(C6)₂(acac) in dilute chloroform solution is 70%. With a device structure of ITO (indium tin oxide)/T-NATA(4,4’,4"-tris(N-(2-Naphthyl)-N-phenyl-amino)triphenylamine)(40nm)/NPB(N,N’-bis(1-naphthyl)-N,N’-diphenyl-1,1’-biphenyl-4,4’diamine)(40nm)/Alq₃(tris-(8-hydroxy-quinoline)aluminum):Ir(C6)₂(acac)(1%)(40nm)/Alq₃(tris-(8-hydroxy-quinoline)aluminum)(40nm)/LiF(Lithium fluoride)(1nm)/Al (120nm), a green color (CIE coordinates x=0.22; y=0.65) and a max luminance of 33792 cd/m² and an efficiency of 12cd/A are obtained. The solid film of Ir(C6)₂(acac) excited at 400 nm shows a strong orange PL emission with a peak at 562 nm. This means When C6 is coordinated with Ir metal; the concentration quench is significantly prevented. As a result, even J is high to 200mA/cm², the device with a structure of ITO/T-NATA/NPB/Alq₃:Ir (C6)₂(acac)(1%)/Alq₃ (40nm)/ LiF/Al can maintain the high efficiency (11.9cd/A) and the high luminance (23683 cd/m²).

An Organic light-emitting diode (OLED) is very promising device for a flat panel display and an illumination applications due to the possibility of very thin and flexible structures, large area emission, high brightness and low power consumption. To realize a high efficiency is one of the most important issues for these applications. Improvements in OLED efficiency are studied via the introduction of photonic crystal (PC) structures, which are expected to realize the versatile control of light. We fabricate two-dimensional PC structures in the organic and indium-tin-oxide anode layers in which most of the light is confined. This results in light extraction from the waveguide mode. Improvements of 20 and 130% are observed in the spectrally-integrated intensity and the peak intensity, respectively, in comparison with samples without PCs. As the thickness of the organic layer is reduced, lower operating voltages are found to maintain the light-extraction efficiency. We can expect further improvement in the overall efficiency by optimizing this structure.

A two-step rapid thermal annealing (RTA) process was investigated for electrical activation of magnesium doped GaN layer. The samples were studied by room temperature Hall measurements and I-V curve. In the two-step RTA process, the first low temperature step (600°C) with a long annealing time (4 min) was followed by the second high temperature (850°C) step with a short annealing time. A hole concentration of 1.39×10¹⁸cm^-3 was achieved for the activated sample. And the specific contact resistance for Ni/Au-contacted p-GaN was determined to be 1.8×10^-4Ω.cm², These results show that the two-step RTA process significantly improves the electrical properties of P-GaN layer compared to the one-step RTA process.

Three dry etching processes using a high ion density inductively coupled plasma (ICP) system in fabrication of optoelectronic device have been briefly presented in this paper. Smooth etched surface, high rate and selectivity ICP InP etching using Cl₂/CH₄/N₂ have been demonstrated first time in fabrications of semiconductor laser. Low damage CH₄/H₂ ICP InP sub-micron grating etching using SiN_x mask can be used for SG-DBR tunable laser fabrication. Anisotropic Cl₂/CH₄/Ar ICP etching with vertical profile has been used for GaAs/AlGaAs DBR layers etching in vertical cavity surface emitting laser (VCSEL) fabrication. The etching characteristics have been investigated by conventional optical microscopy and scanning electron microscopy (SEM).

TiO₂ and Mn_0.2Ti_0.8O₂thin films were prepared by sol-gel process and their structural and optical properties were examined. The structural properties of samples were investigated by the X-ray diffraction (XRD) and auto force microscope (AFM). The XRD results showed that TiO₂ thin film calcined at 650°C was anatase phase, and Mn_0.2Ti_0.8O₂ thin films calcined at the same temperature was rutile. The AFM results of both samples showed quite a smooth surface. Optical properties of samples were examined by UV absorption spectrum. The absorption edge of Mn_0.2Ti_0.8O₂ red-shifted.

It is proposed and demonstrated that the fiber-optic Mach-Zehnder (MZ) interferometry can measure accurately the elector-optic (EO) coefficients of, not only the polymer thin film, but also the polymer waveguide. Furthermore, the tensor components, both r₁₃ and r₃₃, of the EO coefficient can be measured simultaneously. In contrast with the free space MZ interferometer, the fiber-optic MZ interferometer owns some advantages, such as fewer devices, simple experiment configuration, easy operation, and good stability. The most outstanding advantage is that the second electrode need not be fabricated on the top of the polymer thin film. So, the measurement system is especially suitable to measure E-O coefficients of the polymer samples on trial. The closed loop control system of the phase bias of the MZ interferometer decreases the requirement of the environment stability and increases the measurement precision.

The electro-optic coefficient and long-term dipole alignment stability are two major factors in the development of high performance NLO materials for the application of high-speed EO devices. We have developed a high performance non-linear organic chromophore and incorporated it into a crosslinkable side-chain polyimide system. The polymer was synthesized through stepwise grafting of the crosslinker followed by the chromophore onto the polyimide backbone via esterification. Different chromophore loading levels were achieved by adjusting the crosslinker/chromophore feeding ratio. The polyimides films were contact-poled with second-harmonic generation monitoring. A large EO coefficient value was obtained and good long-term thermal stability at 85°C was observed.

Optimizations of organic/polymeric optoelectronic materials and devices in both space and energy/time domains have been studied, both experimentally and theoretically, in order to achieve high efficiency photoelectric conversion. Specifically, at spatial domain, a 'tertiary' block copolymer supra-molecular nano structure has been designed, and a series of -DBAB- type of block copolymers, where D is a conjugated donor block, A is a conjugated acceptor block, and B is a non-conjugated and flexible bridge unit, have been synthesized, characterized, and preliminarily examined for photoelectric conversions. In comparison to simple donor/acceptor (D/A) blends, -DBAB- block copolymers exhibited much better photoluminescence quenching and photoconductivity. These are mainly attributed to improvement in spatial domain for charge carrier generation and transportation in -DBAB- block copolymers then in simple D/A blends. In materials energy levels and electron transfer dynamic regime, theoretical analysis revealed that, the photo (or thermal) excitation induced charge separation appears to be most efficient when the corresponding donor/acceptor frontier orbital level offset is equal to the sum of the charge separation reorganization energy and the exciton binding energy. Other donor/acceptor frontier orbital energy offsets were also identified where the charge recombination becomes most severe, and where the charge separation rate constant over charge recombination rate constant become largest. This dynamically favored charge separation mechanism is also proposed to explain the general 'doping' induced charge carrier generation. Implications of these findings and future approaches are also discussed in order to achieve inexpensive, lightweight, flexible, and high efficiency 'plastic' solar cells or photo detectors.

Various DNA-cationic lipid complexes and their bulk films were prepared and their physical properties were measured. Consequently, it was found that physical properties were greatly dependent on each lipids. The DNA-lipid complexes film formed by C-12 lipid of single-chain trimethylammonium type showed largest value on mechanical strength. Water absorption behaviors of the films were also dependent on kinds of lipids. It was found that fluorescence quantum yields of cyanine doped DNA-lipid films decreased nonlinearly with increasing relative humidity, while the fluorescence quantum yields were high compared with that of PMMA in whole range of relative humidity.

Broad-stripe (greater than or equal to 100 microns) diode lasers have achieved CW powers as high as 15W, and wallplug efficiencies as high as 70%. For high coherent power photonic-crystal structures with modulated gain, that is active photonic crystals (APCs), of large index steps have been used, as early as 1988, for effective lateral-mode control range in large-aperture (100-200 microns) devices. Photonic-bandpass (PBP) structures relying on long-range resonant leaky-wave coupling, so called ROW arrays, have allowed stable, near-diffraction-limited beam operation to powers as high as 1.6W CW and 10W peak pulsed. Photonic-bandgap (PBG) structures with a built-in lattice defect, so called ARROW lasers, have provided up to 0.5W CW stable, single-mode power and hold the potential for 1W CW highly reliable single-mode operation. The solution for high-efficiency surface emission, from 2^nd-order DFB/DBR lasers, in a single-lobe beam pattern was found in 2000. Single-lobe and single-mode operation in a diffraction-limited beam orthonormal to the chip surface was demonstrated, which opens the way for the realization of 2-D surface-emitting, 2^nd-order APCs for the stable generation of watts of CW single-lobe, single-mode power from large 2-D apertures, as well as scalability of such devices at the wafer level.

With the support of state key project, Shandong Huaguang Optoelectronics Co. Ltd. realizes the mass production of low threshold current 650nm GaInP/AlGaInP semiconductor laser chips, rapidly. At present, six million 650nm LD chips can be produced per month. The lowest threshold current at 25°C is 7.4mA. The slope efficiency reaches 1.1mW/mA and the output power is 34mW at 40mA CW operation.

A Novel structure of dual-wavelength semiconductor laser diode is proposed and fabricated. Two laser structures based on two kinds of materials AlGaAs and AlGaInP active layer, which are cascaded by a high doping tunnel junction during the epitaxial growth. The lasers can emit at wavelength of 699nm and 794nm at the same time. Without face coating, the output power of the dual-wavelength laser is high as 50mW at 220mA. And the slope efficiency of these devices is about 0.42A/W.

Usually in the calculation of valence subband structure for III-V direct bandgap material, axial approximation had been used in the Luttinger-Kohn model to simplify the computational efforts. In this letter, the valence subband structure for the GaInP/AlGaInP strained and lattice-matched quantum wells was calculated without axial approximation, on the basis of 6×6 Luttinger-Kohn Hamiltonian including strain and spin-orbit splitting effects. The numerical simulation results were presented with help of the finite-difference methods. The calculation results with/without axial approximation were compared and the effect of axial approximation on the valence subband structure was discussed in detail. The results indicated that there was a strong warping in the GaInP valence band, and axial approximation can lead to an error when k was not equal to zero, especially for compressively strained and lattice-matched GaInP/AlGaInP quantum wells.

The field of integrated opto-electronics on a single InP-based semiconductor substrate has seen significant progress in more than one decade. Although large-scale integration is still a challenging task, building-block components and various integration technologies have been developed, and even relatively simple integrated devices have seen commercial successes in telecommunications. This paper will discuss the potential and practical aspects of photonic integrated devices.

Low cost optical components enable new emerging applications for short distance interconnects. We developed novel VCSEL transceiver modules based on electronics-style plastic packages for large core PCS fiber systems. The transmission data rate is 500Mbps over a wide ambient temperature range from -40°C to 105°C. For lower data rates we developed green LED based transmitters for extended reach applications using POF. On the receiver side MSM photodetectors exhibit a high sensitivity of -18dBm at a data rate of 3.2Gbps. The large area MSM receivers are essential components for high speed large core optical fiber links.

We report the performance of coarse-WDM (C-WDM) uncooled DFB lasers for upper 8 C-WDM wavelengths (1470~1610nm). Due to well-designed structures and well-controlled detuning, low threshold current, high slope efficiency, and high side-mode suppression ratio were maintained even at 85°C. For 2.5Gbps digital applications, these uncooled DFB lasers have clear eye opening, and can transmit through 100km standard single mode fiber with small dispersion penalty (<1dB). For repeater application of mobile communication system, low Relative Intensity Noise (RIN) level of -165dB/Hz at 2.2GHz and -168dB/Hz at 800MHz were achieved respectively at an optimized bias current of over 55mA, and third order distortion (IMD3) was less than -60dBc even at 85°C. For CATV return-path applications, second order distortion (IMD2) of less than -50dBc and IMD3 of less than -65dBc were achieved at 85°C. We performed accelerated aging test and estimated median lifetime was 10⁵hours at 85°C with output power of 5mW.

The key issues of local-area-network (LAN) and storage-area-network (SAN) applications are to improve cost, manufacturability and reliability of optoelectronic devices in high speed transmission. The authors have demonstrated highly manufacturability, reliability and thermal stability mini-transmitter for 10Gb/s Ethernet applications in this paper. Passive alignment technology is a way to improve manufacturability of optoelectronic devices in the future. However, the assembly yield rate of conventional LD chip on silicon optical bench to fiber is quite limited due to restricted optical alignment tolerance (< 1μm). In this study, a novel two lens structure of 10Gb/s LC receptacle type optical mini-flat transmitter is designed and demonstrated to exhibit above 20% coupling efficiency with less than ±6um aligned deviation. Moreover, a high resistivity silicon optical bench (1kΩ/cm) and pressure-free bonding technique using the electroplated AuSn solder are also adopted to guarantee the transmitted performance in high frequency operation. The eye diagram of 10Gb/s mini-flat transmitter developed in this study showing the excellent quality obtained passing 10Gb/s Ethernet mask test with 20% margin. And the extinction ratio of transmitter is also proved to above 6dB at room temperature. The response of monitor PD is also examined up to 80% by mirror coating on silicon V-groove. Thermal stability of 10Gb/s mini-flat transmitter is another critical issue in high speed transmission. The performance of temperature stabilized transmitter over wide case temperature range is also evaluated in this study. The optical eye diagram of 10Gb/s transmitter developed in this paper showing excellent eye quality passing 10Gb/s Ethernet mask test between 0°C to 80°C. Finally, the reliability of transmitter is also performed. The reliability data indicate that the optical alignment of these modules are stable and observed essentially low variations in optical coupling as results of 1000 hours damp heat and 1000 temperature cycling durations.

Silicon photonics, especially that based on silicon-on-insulator (SOI), has recently attracted a great deal of attention. The mature industrial infrastructure of CMOS fabrication offers an opportunity for low cost silicon based opto-electronic solutions for applications ranging from telecommunications to chip-to-chip interconnects. The high volume and high performance manufacturing disciplines are advantageous to electro-optics application development and fabrication. However, many technical hurdles still need to be addressed. This paper will give an overview of these opportunities as well as discuss some practical issues and challenges concerning processing silicon photonic devices in a high volume CMOS manufacturing environment.

A novel scheme of all optical wavelength converter is introduced, in which double-pass configuration based on sum- and difference-frequency generation (SFG+DFG) is proposed for the first time. A concept named "balance condition" is presented to arrange the powers and wavelengths of the two pump sources. Under this condition, the process of SFG is irreversible. Thus, the two pump sources can be utilized completely and the sum-frequency wave can be generated with high power. The efficiency of the system is therefore enhanced. The theoretical expression of the output power of the converted wave and signal are derived when loss is not taken into accounts. In addition, the concept of "Maximum Length" of the waveguide is introduced to avoid the output converted power being reduced due to its oscillating behavior. Finally, the "Maximum Length" is investigated by numerical calculations.

The macroscopic distributions of an electric field and of an induced second-order nonlinearity in a waveguide are for the first time unveiled in case of metal-contact periodic poling. A basic field distribution between a set of electrodes with a generalized arbitrary width is first proposed and then, by using linear superposition and electrode periodicity, the net electric field generated in the whole waveguide is derived explicitly. On the basis of the total electric field, the mean distribution of the nonlinearity and the quasi-phase matching efficiency induced from the total field are defined to analyze the effectiveness in each type of the four periodic poling schemes classified by the configurations of electrode combinations.

The recent observation of enhanced optical transmission through a periodic array of subwavelength apertures in a metal film has elicited significant interest both because it represents a novel phenomenon and because it raises the prospect of a series of new applications. Recently, an ~10⁴ increase in conversion efficiency of second harmonic generation (SHG) from a periodically nanostructured silver film structure consisting of a single subwavelength aperture surrounded by a set of concentric surface grooves was reported. Although the phase-matching condition for extraordinary transmission has been discussed by many researchers, the phase-matching conditions of SHG process was neglected in former experiments. In this paper, we design a silver film with two different sets of periods on a quartz substrate with the silver thickness of 20nm in order to excite long-range surface plasma wave that could transmit millimeter-order distance in the metal surface, which greatly contribution to the improvement of the conversion efficiency of SHG for about 10² times. The fundamental light is perpendicularly coupled into the metal film with about 29 percent coupling efficiency, and the direction of the transmitted SH light is also perpendicular to the metal surface. Furthermore, this new type of structure could contribute to high conversion efficiency of SHG for the virtues of low losses, extremely compact structure and easily fabrication process.

Multiquantum-well (MQW) laser diodes are widely used and being researched for many years. And simulation makes an important part in improving the characteristics of laser diodes. Simulating an equivalent circuit model of lasers is usually used. Many circuit models based on carriers’ and photons’ rate equations have been developed. In the three level scheme, quasi-two-dimensional gateway states between unbound and confined states has been introduced. And it treats each well independently from all the others. So It has more precision than many other models. But before simulation, the parameters in this model are needed. How to get these parameters is vital. But no many people tell us how to do it. This is a complex work. Many parameters can be got from calculation, others must be got from measurement. In this paper the method of getting the parameters is provided. Using these parameters and three level Model for MQW lasers, the dynamic and static behavior are simulated by SPICE circuit emulator.

This paper presents measurement methods for determining the reflection coefficients and frequency responses of semiconductor laser diodes, photodiodes, and EA modulator chips. A novel method for determining the intrinsic frequency responses of laser diodes is also proposed, and applications of the developed measurement methods are discussed. We demonstrate the compensation of bonding wire on the capacitances of both the submount and the laser diode, and present a method for estimating the potential modulation bandwidth of TO packaging technique. Initial study on removing the effects of test fixture on large-signal performances of optoelectronic devices at high data rate is also given.

The carrier lifetime is usually treated as a constant (called as the constant carrier lifetime assumption (CCLA)) during modeling theoretically the chaotic behaviors of semiconductor lasers. In this paper, after considering the actually recombination mechanism of the carriers in the semiconductor and the variation of the carrier lifetime with the time, the chaotic characteristics of semiconductor laser with optical feedback have been investigated numerically, and the obvious differences can be observed compared with those obtained with the CCLA.

The wavelength dependent mode-locking performances of a SOAFL under the backward optical injection via a sinusoidal-modulated distributed feedback laser diode (DFBLD) at 1 GHz repetition rate are characterized. The backward optical injection has to be sufficiently high to saturate a SOA and then depletes most of the excited state electrons in the SOA. In order to obtain shorter mode-locking pulsewidth, the DFBLD injecting wavelength should be slightly longer than the peak wavelength of SOA gain to benefit from shorter gain-recovery time and larger modulation depth. As the wavelength of a DFBLD approach the central wavelength of SOA, the shortest pulse was measured via a digital sampling oscilloscope (DSO). The pulses can also be obtained by DFBLD backward injection at 1535 nm in feedback of SOAFL, leading to the optimized pulsewidths of 22.7 ps.

Quantum dot (QDs) heterostructures structurally represent tiny 3D insertions of a narrow bandgap material, coherently embedded in a wide-bandgap single-crystalline matrix. The QDs are produced by conventional epitaxial techniques applying self-organized growth and behave electronically as artificial atoms. Strain-induced attraction of QDs in different rows enables vertically-coupled structures for polarization, lifetime and wavelength control. Overgrowth with ternary or quaternary alloy materials allows controllable increase in the QD volume via the island-activated alloy phase separation. Repulsive forces during overgrowth of QDs by a matrix material enable selective capping of coherent QDs, keeping the defect regions uncapped for their subsequent selective evaporation. Low-threshold injection lasing is achieved up to 1350 nm wavelength at 300K using InAs-GaAs QDs. 8 mW VCSELs at 1.3 μm with doped DBRs are realized. Edge-emitters demonstrate 10 GHz bandwidth up to 70°C without current adjustment. VCSELs show ~4 GHz relaxation oscillation frequency. QD lasers demonstrate above 3000 h of CW operation at 1.5 W at 45°C heat sink temperature without degradation. The defect reduction technique (DRT) applied to thick layers enables realization of defect-free structures on top of dislocated templates. Using of DRT metamorphic buffer layers allowed 7W GaAs-based QD lasers at 1500 nm.

The coupling efficiency between external plane waves and the Bloch waves in photonic crystals are investigated. It is found that the coupling coefficient is highly angular dependent even for an interface between air n=1 and a photonic crystal with effective index -1. It is also shown that, for point imaging by a photonic crystal slab owing to the negative refraction, the influence of the surface termination to the transmission and the imaging quality is significant. Finally, we present results demonstrating experimentally negative refraction in a two-dimensional photonic crystal.

The independent control of the upper and lower cutoff frequencies of the guided modes in coupled-cavity wavguides (CCWs) is investigated numerically. The CCWs are formed in a two-dimensional photonic crystal (2D PhC) consisting of a square array of dielectric rods in the air. The dielectric constant and radius of the rods in the perfect PhC is 11.56 and 0.18α, respectively, in which α is lattice constant. By using the plane wave expansion method (PWEM), the impact of two influencing factors on cutoff frequencies in CCWs is calculated systematically. Efficient methods have been demonstrated for tuning one cutoff frequency while keeping the other unchanged. The indepent control ranges of the upper and lower cutoff can be up to 67.85% and 68.57% of photonic band gap (PBG), respectively. The results can be applied to the design of PhC-based optical devices such as band filters and optical switches.

Photonic crystals have been widely studied in the fields of physics, material science and optical information technology. In general, the standard rectangular finite difference time domain (FDTD) method is used to predict the performances of photonic crystals. It is however very time consuming and inefficient. The current authors developed a software called GCFE, which is based on a non-orthogonal FDTD method. The software can be used to predict the photonic band structures, photonic states density and transmission and/or reflection coefficients for one-dimensional to three-dimensional photonic crystals. In the present paper, the derivations of the discrete Maxwell’s equations in time-domain and space-domain and the derivation of the discrete transfer matrix in real-space domain are briefly described firstly. In addition, the design idea and the functions of GCFE version 2.0.00 are introduced. Moreover, the band structures, transmission and reflection coefficients and photonic states density for the photonic crystal with cube lattice are calculated by our GCFE software, and numerical application results are also shown.

We investigate a complex cavity composed of three simple cavities, which are formed by three simple defects in a one-dimensional photonic crystal (PC), by the optical transmission method. We set two of the simple cavities to be the same, and let the cavity-length of the third one vary. Generally, two or more narrow resonant transmission modes emerge in the bandgap region; the position of one of them is basically fixed with different fine structures, in which exists a fixed crest, while the other modes wander in the bandgap region as the cavity-length of the third cavity varies. We find the optimized the relative coupling length being 0.447 for the complex cavity. Introducing the parameter - degree of rectangularity, we find that the complex PC cavity is much more close to an ideal narrow band-pass filter than a simple PC defect cavity. It is surprising that the degree of rectangularity is insensitive to the number of periods in the structures.

We report on the synthesis and characterization of crystalline InP and Ga₂O₃ nanowires. The nanowires are synthesized using a simple method based on vapor-liquid-solid (VLS) growth; a method we believe could form the basis of cheap and simple fabrication of crystalline nanowires of a broad range of semiconductor materials, including III-V compounds and semiconductor oxides. The reported InP nanowires have an average diameter of 30nm and the Ga₂O₃ nanowires diameters down to 100nm. Characterization data including SEM, XRD, TEM and PL are presented.

The optical absorption in semiconductor nanorings under a lateral DC field and a perpendicular magnetic field is numerically simulated by coherent wave approach. The exciton dominated optical absorption is compared with the free-carrier interband absorption to demonstrate the key role of Coulomb interaction between electron and hole. The influence of the lateral DC field and the perpendicular magnetic field on the optical absorption are discussed in detail. It shows that the lateral DC field can significantly enhance the Aharonov-Bohm effect of the neutral excitons in semiconductor nanorings.

The capacity of the WDM system can be increased by increasing the useable optical bandwidth or using the available bandwidth more efficiently since bit. Ultra-wide-band WDM transmissions with high bit rates in the full-WDM-wavelength range from the O to U bands (1260-1675 nm) are also very attractive for achieving high-capacity WDM transmission at low cost. This paper represents the high-speed photodetectors with a 3-dB bandwidth of more than 50 GHz for full-wavelength-band WDM transmission systems at 40Gb/s and beyond. The photodetector is a back-illuminated lattice-mismatched InGaAs PIN photodiode that we designed and fabricated to operate with a 3-dB cut-off frequency to values above 40 GHz, in the full-WDM-wavelength range from the O to U bands, by applying a small junction diameter and reduced the thickness of the light-absorbing InGaAs layer with a lattice-mismatch of +0.2% to InP. For our photodiode modules, a 3-dB bandwidth as high as 65 GHz was achieved at a bias voltage of 3 V and the responsivities at wavelengths of 1310, 1552 and 1670 nm were 0.6, 0.65 and 0.55 A/W, respectively. 40Gb/s receivers and 10Gb/s PIN/TIA modules were described as applications of the FWB-PDs. The photodiode modules operating up to the bandwidth of 50GHz and above in the full-WDM-wavelength range can drive the development to 40Gb/s WDM transmission systems using RZ or NRZ format and the additional new channels in the U band.

A novel top-illuminated metamorphic In_0.53Ga_0.47As p-i-n photodiodes (MM-PINPD) grown on GaAs substrate by using a linearly graded In_xGa_1-xP (x graded from 0.51 to 1) buffer layer is reported. The dark current, optical responsivities, noise equivalent power (NEP), and operational bandwidth of the MM-PINPD with aperture diameter of 60 μm are 13 pA, 0.77/0.59 (1310/1550 nm) A/W, 6.9x10^-11 W/Hz^1/2, and 7.5 GHz, respectively. The performances of the MM-PINPD on GaAs are demonstrated to be better than those of a similar device made on InGaAs/InP substrate.

A novel integrated, Resonant-cavity-frequency-selectivity Inclined-mirror Coupling Encapsulated-core Wave-Guide (RICE WG) photodetector is described. Detailed design processes and numerical simulations are investigated theoretically. The novel structure makes device’s quantum efficiency decouples with its response bandwidth and spectrum linewidth simultaneously. Through performance simulation and optimization, the results indicated that the tradeoff between spectral response linewidth and quantum efficiency no longer exist. RICE WG PIN can achieve spectral response linewidth <1nm and quantum efficiency >80% simultaneously. Additionally, we discussed the approach to realize it.

Type-II interband cascade lasers are efficient and compact mid-infrared (3-5 μm) light sources with many applications such as gas sensing and environmental monitoring. Significant progress toward such a goal has recently been made in terms of achieving low threshold current densities (e.g. ~8 A/cm² at 80 K), high temperature operation (e.g. 325 K in pulsed and 217 K in cw modes), and continuous wave operation of single-mode distributed feedback (DFB) lasers. These DFB lasers have been integrated into laboratory spectrometers for detection of gases such as CH₄ and HCl. One laser was flown on a high-altitude balloon instrument and measured HCl profiles in the stratosphere as part of Aura satellite instrument validation. We review the recent progress of Sb-based mid-IR IC lasers and address the requirements for further improvements in their performance.

This paper analysis the spectral characteristics of optical pulse amplifications in semiconductor optical amplifiers under transparent assist light injection, comparison with the gain region light injection is also been given. It is shown that gain region light can decrease the spectral broadening and shifting, while transparent light can’t improve the spectral distortion though it can accelerate the carrier recovery. The effect of the assist light’s power, shape and initial frequency chirp of the input pulses on the shape and the spectrum of the amplified pulse are discussed in detail. The relationship of the maximum spectral shifting with the amplifier’s length, bias current is also been given, particular attention is paid to the difference in co- and counter-propagating assist light injection.

The polarized emission behaviors of the Eu³⁺ doped azo-polymer waveguide were reported in this paper. Affected by the azobenzene groups in the photoinduced orientation process by the 532nm linearly polarized laser, the ligands were realigned orderly perpendicular to the direction of the orientation direction. This leads to the polarized absorption and emission of the waveguide in the orientation direction. By an m-line apparatus based on the prism coupling technique, two guided modes propagation were observed in the waveguide at 650nm in TE polarizations.

Progress of information technology in recent years has led to a rapid expansion in data communication capacity and there has been a strong demand for constructing cost-effective and high-performance optical communication systems. Photonic integrated circuit (photonic IC) technology has offered solutions for these requirements by eliminating the individual packaging and optical connections between devices. This approach is expected not only to reduce the cost, size, and power consumption but also to realize new functions that can never be possible with conventional discrete devices. For the practical use of photonic ICs, it is desirable that they can be used under uncooled conditions and are highly productive. However, it seems difficult for conventional InP-based devices to satisfy these requirements because their temperature characteristics are insufficient due to a weak electron confinement in the active region. In addition, at present, InP substrates used for production are mainly 2 or 3 inches in diameter and it is difficult to enlarge the wafer size with maintaining the quality and mechanical strength. GaInNAs, which has been developed recently as an alternative semiconductor material in the long-wavelength region, seems to be the best candidate to satisfy these requirements. It covers bandgaps corresponding to the wavelength from 1.3 μm to 1.6 μm with lattic-matched to GaAs, which leads to the following advantages. First low-cost and large-scale integrations can be realized with high productivity due to the usage of large GaAs substrates of up to 6 inches in diameter and well-established Ga-As-based process technology. Second as well known in GaInNAs lasers, much stronger electron confinement in the active layer can be realized. Therefore GaInNAs-based devices are expected to have larger gain and better temperature characteristics comparing with conventional InP-based devices. In addition, the low Auger recombination rate and large effective mass of electron would also improve gain and temperature characteristics. The crystal quality of GaInNAs has been improved rapidly in several years. Threshold current densities of GaInNAs lasers have been reduced more than one figure and both molecular beam epitaxy (MBE) and organometallic vapor phase epitaxy (OMVPE) can provide high quality GaInNAs as shown in figure 1. The threshold current density reached 200A/cm² level at 1.3 μm region which is low enough to be used for practical applications. Therefore GaInNAs is thought to be a key material in photonic ICs in the long wavelength region. Semiconductor lasers and semiconductor optical amplifiers (SOAs) are key components of photonic ICs functioning as light sources, switches, amplifiers, wavelength converters and so on. In this paper, as the first study for photonic integration using GaInNAs, we present very low threshold current GaInNAs lasers and GaInNAs SOAs operating 1.3 μm region with good temperature characteristics.

All-optical switches being developed in the Femtosecond Technology Project are reviewed. New operating principles and new materials are introduced to attain low switching energy and very fast switching of 160Gb/s to 1Tb/s. Basic operation of the switches are demonstrated and some of the switches are tested in system experiments.

Novel all-optical logic AND gate based on cross-gain modulation in cascaded semiconductor optical amplifier (SOA) is presented in this paper. Theoretical model for this novel configuration is established, all-optical logic AND operation function at 10Gb/s is numerical simulated and experimental demonstrated. Output logic operation results in different operation conditions are also analyzed. Results show that single-port-coupled SOA is helpful for better output performance and enough output power of the first stage wavelength converter is critical for logic AND operation results, theoretical simulation results are coincidence with experimental results.

A scheme for all-optical logic OR based on transparent teraherz optical asymmetric demultiplexer (transparent-TOAD) is proposed in this paper. In the transparent-TOAD, the SOA is biased at transparency and the gain recovery time determined by the intraband effect has the value of only a few picoseconds. Numerical analysis shows that the switching window of the transparent-TOAD is only about 0.54ps and the potential for ultrahigh speed all-optical logic processing is shown. Numerical demonstration is performed for 4-bit and 16-bit logic OR at 20Gbit/s. The results coincide with the OR truth table, showing high extinction ratio and no pattern dependency. Detailed analysis is carried out on the performance of the logic OR scheme.

Proposed in this paper is a novel packet-level self-synchronization scheme with Semiconductor optical amplifier based symmetric Mach-Zehnder interferometer (SOA-MZI). The effect of cross-phase modulation (XPM) and cross-gain modulation (XGM) in SOA and the interfering characteristics of MZI are combined to make the proposal simple, fast and integrable, with no special treatment of the marker pulses. Through numerical analysis and properly design of the parameters, more than 20dB intensity contrast ratio of 100G/s RZ pseudorandom bit sequence can be achieved.

This paper describes a fully packaged 4x4 optical crosspoint switch (OXS) device and several of its application demonstrations. The core switch chip is based on Bristol’s unique active vertical coupler (AVC) switching technology. The 4x4 switch is pigtailed with 4-fibre lensed arrays using a Si V-groove technique. The packaged device is further interfaced via an electronic decoder/driver circuitry. Several novel experimental demonstrations are carried out, including optically addressed optical uni-cast routing, optical multicast routing, and packet level automatic gain control (AGC). These experiments highlight the unique performance and versatility of the AVC OXS device.

A novel optical element, Dual-Cylindrical Prism, designed to generate and homogenize a laser beam line at an arbitrary working distance, is presented. The element with entrance surface consisting of two cylindrical shaped concave surfaces, and exit surface a single cylindrical concave, splits and overlaps the laser beam along fast axis and collimates the beam along slow axis, redistributing the diode laser output beam to a line with uniform intensity distribution and flexible working distance. The technique to design such a device is provided, and the computer-aided simulation results demonstrate the uniformity of the laser line and also the feasibility of such a device.

A novel measuring implementation based on second-harmonic generation frequency-resolved optical gating (SHG-FROG) has been presented. Both the intensity and phase of arbitrary-shaped ultra-short laser pulses can be got. According to SHG-FROG, the femtosecond pulse produced by a laser resource is split into two beams which variable time delay one another is controlled by a stepped electromotor. The second-harmonic signal field is generated by focusing these two beams to a 100um BBO crystal. Changing the delay from 0 to N (N is the samples number of time domain or frequency domain) delay units, the two-dimensional spectrum data of the second-harmonic signal field are acquired by PC2000-ISA card spectrometer and OOIwinIP of Ocean Optics. These data are provided to a pulse amplitude and phase retrieval algorithm to retrieve the parameters of the pulse. An experimental system is erected and the all software modules, including spectrum data acquiring, pulse retrieving and displaying, are based on Labwindows/CVI of National Instrument Corp. The stepped electromotor is driven by the commands coming from RS-232 interface. The results show that after 50 times iterations or so, the iterative error of the algorithm can be reduced to an enough small value and then the pulse amplitude, phase and other parameters are the desired parameters. The whole measuring process can be finished in 2~3 seconds while the spectrum data is a 64x64 matrix and the iterative times are set to 50.

Modes in equilateral triangle resonator (ETR) are analyzed and classified according to the irreducible representations of the point group C_3v. Both the analytical method based on the far field emission and the numerical method by FDTD technique are used to calculate the quality factors (Q-factors) of the doubly degenerate states in ETR. Results obtained from the two methods are in reasonable agreement. Considering the different symmetry properties of the doubly degenerate eigenstates, we also discuss the ETR joined with an output waveguide at one of the vertices by FDTD technique and the Pade approximation. The variation of Q-factors versus width of output waveguide is analyzed. The numerical results show that doubly degenerate eigenstates of TM_0.36 and TM_0.38 whose wavelengths are around 1.5μm in the resonator with side-length of 5μm have the Q-factors larger than 1000 when the width of the output waveguide is smaller than 0.4μm. When the width of the output waveguide is set to 0.3μm, the symmetrical states that are more efficiently coupled to output waveguide have Q-factors about 8000, which are over 3 times larger than those of asymmetric state.

We have investigated many different types of Nd solid state lasers and the passive modulator materials that can passively Q-switch, mode-lock, Q-switched mode-lock all the above solid state lasers. The mechanism of the typical Q-switched mode-lock mechanisms were proposed and analyzed in detail. In all the microchip laser developments, the only tolerance that can reduce the physics size, optimize the modulated output efficiency and minimize the component price is to use the doped single crystal semiconductor saturable absorbing modulators as we are proposing. We have used the MEMS technologies for the fabrication of the most compact, highest efficiency and most low price semiconductor substrate microchip laser. Two out of four components of the various direct generation as well as OPO generation of the microchip lasers that generate visible, near infrared and infrared wavelengths and with Q-switch, mode-lock, Q-switched mode-lock modulation could be achieved.

Theoretical simulations and experimental studies of power limiting effect in four Brillouin media have been given in this paper. One-dimensional coupling equations are used to stimulate the propagation of nonlinear laser pulse in four SBS media. The transmitted temporal pulse profiles through SBS medium with various pump energies are numerically simulated, then temporal pulse reshaping, power limiting dependent on SBS Gain of medium in four SBS media are investigated theoretically. By using Nd:YAG laser pulses with 20ns pulse duration and four Brillouin media such as CCl4, Fc-72, CS2 and acetone, Temporal profiles reshaping and power limiting characteristics are given experimentally. Those SBS limiting effects have characteristics as follows: CCl4, Fc-72 give higher limited power, CS2 and acetone give lower limited power. The control rule of power limiting dependent on Gain of medium is exhibited in theoretical calculations and experiments as follows: Smaller gain of medium system will give higher limited power, at mean time; higher gain of medium will give lower limited power. The above study makes SBS suitable to be applied in the protection and stabilization of high-power laser system.

A kind of novel optic strip waveguide phase modulator driven by a surface acoustic wave (SAW), applied to the signal modulation of photo-electronic-integrated accelerator based on Mach-Zehnder interferometry, present in this paper. The characteristic parameters of the acoustooptic modulator are investigated theoretically and experimentally. Measurements were performed on ZnO thin film deposited on Si substrate with f₀=48MHz at λ₀ = 1.3μm optical wavelength using K₉ glass waveguide. The main parameters of the modulator is as following: the ZnO thin film with the dimensions of 5 mm x 0.8 mm x 0.003 mm; Interdigital transducer with the fingers of 17 pairs, the electrode aperture width of 4.46 mm and the interdigital period of 27.19 μm.

We report on multiphoton-induced periodic microstructures inside bulk polymers by multibeam interference of femtosecond laser pulses at a wavelength of 800 nm, which is out of the absorption range of the polymer sample. Two-dimensional structures and three-dimensional periodic microstructures were fabricated inside bulk azodye-doped polymethylmethacrylate by four-beam interference and five-beam interference, respectively. The Raman spectra measurements for the photoinduced area of the sample before and after irradiation with the writing light showed that the periodic microstructures probably arose from photoinduced decomposition reaction of azodye molecules through multiphoton absorption. Two-dimensional and three-dimensional periodic microstructures were also fabricated in photopolymerization by four-beam and five-beam laser interference, respectively.

In this paper, firstly the spectral response of transmission-type GaAs photocathode is measured online by the spectral response-testing instrument. Then the cathode is sealed in the third generation intensifier and put into the instrument again to get another spectral response curve. The variation of spectral response curves was compared. The results show that through the seal process, the spectral response in the long wavelength decrease. Based on these curves, the spectral matching factors of GaAs photocathode for green vegetation and rough concrete are calculated. The calculated performance parameters show that the variation of the spectral response in the seal process is an important influence factor on the performance of the intensifier in the use of night vision.

In this letter, a novel broadband optical fiber type M-Z modulator with traveling-wave electrode is proposed. Since the waveguides are formed using special optical fiber, the microwave field is concentrated in the optical fiber regions. The finite element method has been used to analyze the microwave equivalent refractive index and characteristic impedance. Then, the performance of the modulator has been simulated using the neural network. The calculated and simulation results are shown in figures. Compared with the conventional modulator, the novel modulator can easily obtain the velocity matching and impedance matching. Using this structure, we have developed a fiber type M-Z modulator with 80GHz 3dB bandwidth, 1.18V half-wave driving voltage, and 55.5Ω impedance.

By placing the semiconductor lasers in series or parallel with different resistances, the effects of series and parallel resistances on noise level of devices are studied. The effects of serial and parallel resistances on device quality and the correlations between the noise level and reliability of semiconductor lasers are also discussed. The results indicate that the noise level does not change obviously when the devices are placed with serial resistance. At the bias current of 5mA, the parallel resistance also has no obviously effect on noise level. But, when the bias current is 20μA, the parallel resistance makes noise level of devices decrease evidently. The devices with lower noise may also be unreliabile.

In this paper, a novel chiral photonic crystal structure is presented. The formula of reflection coefficient of multi-layer chiral media is applied to dielectric-chiral photonic crystal structure, which is composed of thin chiral layers sandwiched by conventional media. To compare with previous literature, we consider the dielectric structure with alternate glass and GaAs layers. The power reflectance as a function of wavelength for this photonic crystal structure has been calculated. The results are in good agreement with that of Reference. However, our method is simpler. From these graphs, it is found that 100% reflectance is only in finite wavelength ranges, and reflection bandwidth is also small for conventional photonic crystal structure. For chiral photonic crystal, the results show that the chiral photonic band gap (PBG) structure gives nearly 100% reflections in the near-infrared region in addition to some parts of the visible region of the wavelengths. Therefore, it can be used as a broadband reflector and filter.

A relatively perfect steady-state and dynamic numerical model of SOA considering facet reflectivity, gain dispersion and amplified spontaneous emission (ASE) spectrum is established to make it closer to reality. Based on the proposed numerical model, carrier recovery time is investigated under different external conditions theoretically and experimentally. Via the analysis of results of simulation and experiments, schemes for accelerating carrier recovery are explored.

The characteristics of the polymer modulator are determined by many interrelated physical phenomena. The key issue of this paper is to find out the optimum device parameters and corresponding conditions by taking into account all the related factors. The optical field in ridge waveguides is calculated using the FEM software with MATLAB and then fit to a Gauss function. The parameters such as half-wave voltage, bandwidth are calculated using the FEM software with FORTRAN language. In the calculating results, the comprehensive characterization of the polymer modulator with 1.21v half-wave voltage, 91GHz bandwidth is presented, electro-optic interaction length is 20mm, electro-optic coefficient is 55pm/V, and wavelength is 1.319μm. These results fit the 0.8v half-wave voltage, electro-optic interaction length is 30mm reported on Science perfectly. More important, five structures of polymer modulators are presented all together and are compared of the merits and shortcomings. One of them is a combination of CPW and microstrip lines. The characterization of this structure is like that of the microstrip lines with single arm electrode on one arm of the waveguide, but it solves the problem of microstrip-coaxial transition and corona polarization.

The high power bottom-emitting vertical-cavity surface-emitting lasers (VCSELs) with a wavelength of 980nm are described. The device has been fabricated by using oxidation confinement technology. Al2O3 film, instead of SiO2 film is used as the passivation layer to enhance heat dissipation. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance is discussed.

In the paper, a weighted-coupling scheme of a SiO₂ film-loaded Ti:LiNbO₃ quasi-collinear integrated acousto-optic mode converter is reported, in which an angular offset between the acoustic and optical waveguides is introduced to implement an optimized Hamming weighted function for realization of ultralow sidelobe level. Acoustic wave guiding properties have been investigated for films such as SiO₂, ZnO on LiNbO₃ firstly. SiO₂ film on LiNbO₃ was selected as acoustic waveguide. With the mode analysis of the acoustic wave guide and the theory of coupling mode the limit of the width, weighted coupling coefficient and the characteristics of the conversion of acousto-optic modes are obtained. As the angle between acoustical and optical waveguides is 0.45°, the worst sidelobe level is -16dB and the theoretical values of bandwidths of -3dB and -10dB is 1.37nm and 2.31nm respectively, which have excelled the domestic reported level.

Several kinds of disperse-dye polymer films of the guest-host system were prepared by spin-coating method. Disperse orange 25 (DO25), disperse orange 3, disperse red 73, and disperse yellow 9 were chosen as nonlinear optical (NLO) active chromophores and polymethylmethacrylate (PMMA), polycarbonate (PC), and polyetherimide (PI) as polymer matrixes. Polymer films were poled by all optical poling or electric corona poling. The glass transition temperature (Tg), absorption spectra, rigidity, NLO properties of polymer films were characterized by means of DSC, UV-IR spectra, microhardness analyses, and NLO measurements. The all-optical poling characteristic of four kinds of NLO chromophores in PMMA matrixes systems has been investigated. DO25/PMMA has largest NLO effect. The possible explanation has been proposed. The relaxation and rigidity characteristics of DO25 doped polymer matrixes with various Tg have been studied by means of corona poling method. It is found that DO25/PI polymer films show best thermal and temporal stability and DO25/PMMA has largest NLO property. Generally, DO25/PC system has optimal tradeoff properties of NLO and stability. In addition, the second-order NLO coefficient and average electro-optic coefficient of 10wt% DO25/PMMA poled by optical poling and corona poling is determined to be around 60 and 34 pm/V, respectively.

A novel driving scheme utilizing the resonance effect of the micro-mirror is presented to reduce the drive voltage of the silicon-based MEMS (microelectromechanical systems) torsion-mirror optical switch. A mixed bias of DC (direct current) and AC (alternating current) is adopted to drive the torsion mirror. Both the numerical simulation and experiment results show that the driving voltage of the optical switch is reduced by nearly 50%, from more than 270V to 130V.

A novel technique is presented in obtaining the performance characteristics of traveling-wave semiconductor optical amplifier (TWA) with tensile-strained-barrier multiple-quantum-well structure. In-out fiber ends of TWA are used to construct an external cavity resonator to produce big ripple on amplified spontaneous emission (ASE) spectrum. By this means, Hakki-Paoli method is adopted to obtain gain and differential gain spectra over a wide spectral range. From measured longitudinal mode spacing and peak wavelength shift due to increased bias current, we further calculate the effective refractive index, carrier-induced refractive index change and linewidth enhancement factor. Some special features about ASE mode spectrum shift and refractive index change above lasing threshold are revealed and explained.

In this paper the theoretical analysis of low frequency noise sources in Optoelectronic Coupled Devices (OCDs) is given and the relation between typical defects and low frequency noise that consists of 1/f, generation-recombination (G-R) and burst noise is described. A novel measurement system for low frequency noise is introduced here, and nV-level measurement precision can be achieved with the typical low-frequency noise measuring system, which is based on virtual instrumentation. According to statistical and experimental results, a threshold to screen potential devices with excess noise is derived, which has been proved theoretically that the screening criterion is reasonable. Contrasting the former screening criterion, some familiar noise parameters of devices are adopted to establish a novel screening criterion in this paper. At last, the Levenberg-Marquardt regression algorithm is used for the low-frequency noise parameters fitting. The noise parameters are very useful for analyzing the defects.

Long wavelength InGaAs/InGaAsP MQW wafers are grown by MOCVD technique. Novel structure microcavity laser is fabricated with this MQW material. This microcavity laser is integrated with one or two directional output waveguides, which is connected to the microcylinder or microring. The diameter of microcylinder laser is 10 to 60 micron and the width of the directional waveguide is 10μm with a length of 300micron. Low threshold current of 5mA and multi-mode lasing emission is realized in pulsed operation.

For reducing turn-on voltage of GaAs-based HBT, Al_0.25Ga_0.75As/GaAs_0.89Sb_0.11/GaAs DHBTs on GaAs (001) is successfully grown by solid-source molecular beam epitaxy (SSMBE) with a GaAs decomposition source, no misfit dislocation in the base layer was found by observation of SEM. It suggests that GaAsSb base layer is fully strained. Device with 75x75μm2 emitter mesa area is fabricated using this structure and yielded an excellent performance with high current gain of 30 at the collector current density of 2×10³A/cm² and low turn-on voltage of 0.8V. Due to the smaller band gap of the GaAsSb base layer, GaAsSb is useful material for reducing turn-on voltage of GaAs-based HBTs.

980nm InGaAs/GaAs separate confinement heterostructure (SCH) single quantum well (SQW) laser is grown by MBE. Photoluminescence and X-ray double crystal diffraction of the epilayer demonstrate good optical and crystalline quality. A QCW output power of 64.1W is achieved for a cm bar, which is limited by the current source. No thermal rollover in the output power is observed. The threshold current is 18.6A at 15°C. The slope efficiency is 1.14W/A with a corresponding power efficiency of 31.7%.

Model is developed for the dc I-V characteristics and microwave small-signal parameters of the InP-based In_0.52Al_0.28As/In_0.65Ga_0.35As HEMT’s based on physical principles, and the effect of the extrinsic source and drain resistances has also been included. Using the parameters obtained by this model and the small-signal model of PIN detector, we simulated the transimpedance configurations with an inverter and a cascode input circuit of monolithically integrated PIN-HEMT front-end optical receiver. The results indicate that the cascode input stage can realize a smaller input capacitance than the inverter-type, so it has a wider bandwidth. In order to operate in 2.5Gb/s transmission system, the cascode input stage is applied and the parameters are optimized. The simulations reveal that the transimpedance gain is larger than 63.2dBΩ and the sensitivity is 30dBm when the bit rate is 2.5Gb/s. The results obtained in this paper provide a guideline for the fabrication of PIN-HEMT optical receiver.

Based on the model of microcavity theory and transfer matrix theory, we measured the influence of complex cathode by introducing dielectric layer. Dielectric layer greatly influence the property of microcavity. Complex cathode may have obvious improvement to the trait of microcavity. Both in the instances considering microcavity effect and not considering, we compared the reflectivity, phase of reflection and light outcoupling efficiency of complex cathode with that of single layer metal cathode. To make the model simple, we do not consider complicated effect induced by interface absorbance and combination, we got the greatest improvement to outcoupling efficiency at certain instance. The efficiency of optimum structure is twelve times higher than that of single metal layer cathode. This confirms that dielectric layer can be used to improve the performance of organic metal cavity devices. Based on this kind of structure, unsymmetrical metal may reach great application.

In this paper, the technology of molecule saturation absorption frequency stabilization of the external cavity laser diodes (ECLD) on 1.5μm which is recently researched is discussed, and it can obtain high ratio of precision. The improved scheme of the servo circuit system of the ECLD’s molecule saturation absorption frequency stabilization is investigated in the paper. The peripheral loop servo circuit system is the key of the frequency stabilization control. The original servo system uses a lot of discrete components. Its structure is intricate and the performance is not stable enough. In the paper, the parts of the peripheral closed loop servo are conformed in an FPGA slug. This module can realize the closed loop control functions which are necessary for the frequency stabilization. So, the whole system is not only integrated and minityped, but also can be intelligent controlled; the stabilization is greatly increased, and it enables the accuracy to reach 10^-8rad.

Inkjet printing technology has begun to get into the spotlight in many ways due to the superior price competitiveness to existent semi-conductor process. This paper will introduce a newly devised gap adjustable inkjet printing system for dense and high-temperature-melting materials such as metal paste. The design on the gap adjustable inkjet printing system is discussed in detail for precise control of the size and spacing of the injected metal droplets. Analytic optimization and effects of design parameters are examined and computational work using the axis-symmetric, incompressible, multiphase equations is carried out to predict characteristics of the metal paste jetting and to design optimal micro nozzle prototype. From this analysis, droplet trajectory visualization and velocity vector of ejected droplet have been investigated to characterize the relationship between inlet condition and nozzle profile. Finally, the designed gap adjustable inkjet printing system is fabricated and its peformances are tested according to the change of various gap distances and the droplet characteristics are measured in the view point of precise droplet controllability and productivity.

This paper describes a 12-channels parallel optical transmitter module with a MPO-Connector designed for a very short reach OC-192 and SNAP 12 specifications. It is important to design the micro array lens for better couple efficiency of array optical transmitter module. The authors design the high accuracy micro array lens for injection modeling to reduce the price and suit for further mass production. In this 12-channel parallel optical transmitter module, it is very difficult to posit the chip on correct position according to guide pin or guide pin hole. Therefore, the authors develop the method of two steps flip chip bonding to release the difficulty of chip alignment on ceramic substrate without two guide pin holes. The performance of the module is demonstrated to fulfill the requirements of SNAP 12[1]. The extinction ratio of the 12-channels array transmitter module is tested above 6dB, respectively. The optical shift by heat is an important factor affecting the performance of the array module. Thermal analysis of 12-channel parallel optical transmitter module is used to improve the effect of optical shift by heat in this paper. And the temperature among the case of transmitter module is greatly reduced from 52.7 degree to 31.9 degree. In this paper, a 12-channel array transmitter module package and thermal simulation are discussed and tested. This is a low cost package design and is suitable for mass production.

In this paper, we demonstrate the design, fabrication and characterization of a long wavelength InP-based resonant cavity photodetector with InP/air-gap Bragg reflectors by using selective wet etching. The bottom mirror of the RCE photodetector is the InP/air-gap Bragg reflector; the top mirror is formed by the interface of semiconductor/air. The In0.53Ga0.47As absorption layer thickness is 300nm. A peak quantum efficiency of 60% at 1510nm and a 3-dB bandwidth of 16GHz are achieved with the active area of 50×50μm². The dark current as low as 2nA was achieved at reverse bias of 3.0V.

This paper introduces some optic-electronic detectors which are applied in Satellite Laser Ranging (SLR) system, such as XP2233B, GDB49, MCP (Micro Channel Plate)-PMT (Photomultiplier Tube), SPAD (Single Photon Avalanche Diode), etc. The comparisons of these detector’s performance and main parameters are given. With the improvement of the parameters, the laser range precision and system stability are improved. The focus is on the widely used detectors -- MCP-PMT and C-SPAD. After comparing the advantage and disadvantage of the two kinds of detectors, the range precision and system stability improvement are presented based on the detectors.

A cost-effective and compact WDM-PON source amplification scheme with bidirectional semiconductor optical amplifier is firstly demonstrated. A linear optical amplifier is used as a bidirectional amplifier to obtain the gain clamping of downstream channels and suppress the cross-gain modulation between upstream and downstream channels. We show the experimental results including the transient responses with a dynamic wavelength channel add/drop in WDM-PON.