Proceedings Volume 3551

Integrated Optoelectronics II

BingKun Zhou, Ray T. Chen
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Proceedings Volume 3551

Integrated Optoelectronics II

BingKun Zhou, Ray T. Chen
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 12 August 1998
Contents: 3 Sessions, 37 Papers, 0 Presentations
Conference: Photonics China '98 1998
Volume Number: 3551

Table of Contents

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Table of Contents

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  • Thin Film Optoelectronic Material and Simulation
  • Thin Film Optoelectronic Devices
  • Device and System Application Using Integrated Optoelectronic Circuits
  • Thin Film Optoelectronic Devices
  • Thin Film Optoelectronic Material and Simulation
  • Device and System Application Using Integrated Optoelectronic Circuits
  • Thin Film Optoelectronic Material and Simulation
Thin Film Optoelectronic Material and Simulation
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Nature of iron in InP: an FTIR study
Yujie Han, Xunlang Liu, Jinghua Jiao, et al.
Fe is still the commonly used dopant to fabricate semi- insulting (SI) InP, a key material for high-speed electronic and optoelectronic devices. High resolved absorption spectra of the internal d-d shell transitions at Fe2+ in InP and the related phonon sidebands and a series of iron related absorption lines are presented. Detailed infrared absorption study of the characteristic spectra of four zero-phonon lines (ZPLs), which are attributed to transitions within the 5D ground state of Fe2+ (3d6) on the indium site in a tetrahedral crystal field of phosphorus atoms and their temperature effects are given.
Dynamics of defect formation in annealed InP
Yujie Han, Xunlang Liu, Jinghua Jiao, et al.
Dynamics of formation of defects in the annealed nominally undoped semi-insulating InP obtained by high pressure, high temperature annealing of high purity materials is proposed. Incorporated hydrogen passivates vacancy at indium site from annihilation forming fully hydrogenated indium vacancy which dissociates leaving large lattice relaxation behind, deep donors, mainly larger complexes involving phosphorus at indium site and isolated hydrogen defects are created in nominally undoped InP after annealing. Also created are acceptor levels such as vacancy at indium site. Carrier charge compensation mechanism in nominally undoped InP upon annealing at high temperature is given. Microscopic models of hydrogen related defects are given. Structural, electronic and vibrational properties of LVMs related to hydrogen as well as their temperature effect are discussed.
GaP/Si heterostructures grown by GS-MBE
Jinzhong Yu, Buwen Cheng, Zhuo Yu, et al.
GaP/Si is a promoting heterostructure for Si-based optoelectronic devices since lattice constants of GaP and Si are so closed that they can match with each other. GaP was successfully grow on (100) Si subtracts by Gas-Source Molecular Beam Epitaxy (GS-MBE) in the study. The GaP/Si heterostructure was characterized by X-ray double crystal diffraction, Auger electron spectrograph, X-ray photonic spectrograph and photoluminescence (PL) measurements. The results showed that the epitaxial GaP layers are single crystalline, in which a (parallel) and a (perpendicular) are 0.54322 and 0.54625 nm, respectively. The peaks in PL spectra of GaP epitaxial layer grown on Si are 650, 627 and 640 nm, respectively. The study demonstrated that GaP/Si is a kind of lattice matched heterostructures and will be a promoting materials for future integrated photonics.
Preparation and photoluminescence of nc-Si/SiO2 MQW
Buwen Cheng, Jinzhong Yu, Zhuo Yu, et al.
The deposition rate and refractive index for a-Si(amorphous silicon) and SiO2 grown by PECVD were studied under different pressure, power and proportion of reactant source gases. a-Si/SiO2 MQW(multi-quantum well) with high quality was deposited under suitable conditions, in which the thickness of the a-Si layers is several nanometers. The sample of a-Si/SiO2 MQW was crystallized by laser annealing. Because of the confinement of the SiO2 layers, crystalline grains were formed during the a-Si layers were being crystallized. The size of the crystalline grains were not more than the thickness of the a-Si layers. The a-Si layers were crystallized to be nanometer crystalline silicon (nc-Si), therefore, nc-Si/SiO2 MQW was formed. For the a-Si/SiO2 MQW with 4.0 nm a-Si wells separated by 5 nm SiO2 barriers, most of the a-Si were crystallized to silicon grains after laser annealing, and the size of the grains is 3.8 nm. Strong photoluminescence with three peaks from the nc-Si/SiO2 MQW was detected at 10 K. The wavelength of the peaks were 810 nm, 825 nm and 845 nm, respectively.
SPER and characteristics of Si1-yCy alloys
Zhuo Yu, Jinzhong Yu, Buwen Cheng, et al.
Si1-yCy alloys with carbon composition of 0.5 at% were successfully grown on n-Si(100) substrate by solid phase epitaxy recrystallization. The result was presented in this paper. With the help of the SiO2 capping layer, rather uniform carbon profile in amorphous Si layer was obtained by dual-energy implantation. Since ion-flow was small and implantation time was long enough, the emergency of (beta) -SiC was avoided and the dynamic annealing effect was depressed. The pre-amorphization of the Si substrate increased the fraction of the substitutions carbon and the two-step annealing reduced point defects. As a result, Si1-yCy alloys with high quality was recrystallized on Si substrate.
Design and fabrication of GaAs OMIST photodetector
Xuejun Kang, ShiMing Lin, Qiwei Liao, et al.
We designed and fabricated GaAs OMIST (Optical-controlled Metal-Insulator-Semiconductor Thyristor) device. Using oxidation of AlAs layer that is grown by MBE forms the Ultra- Thin semi-Insulating layer (UTI) of the GAAS OMIST. The accurate control and formation of high quality semi-insulating layer (AlxOy) are the key processes for fabricating GaAs OMIST. The device exhibits a current-controlled negative resistance region in its I-V characteristics. When illuminated, the major effect of optical excitation is the reduction of the switching voltage. If the GaAs OMIST device is biased at a voltage below its dark switching voltage Vs, sufficient incident light can switch OMIST from high impedance low current 'off' state to low impedance high current 'on' state. The absorbing material of OMIST is GaAS, so if the wavelength of incident light within 600 to approximately 850 nm can be detected effectively. It is suitable to be used as photodetector for digital optical data process. The other attractive features of GaAs OMIST device include suitable conducted current, switching voltage and power levels for OEIC, high switch speed and high sensitivity to light or current injection.
Electroluminescence and photoluminescence of Si/SiGe self-assembly quantum dot structures
Junjie Si, Qingqing Yang, Hongjie Wang, et al.
Comparative electroluminescence (EL) and photoluminescence (PL) measurements were performed on Si/Si0.6Ge0.4 self-assembly quantum dots (QDs) structures. The samples were grown pseudomorphically by molecular beam epitaxy, and PIN diodes for electroluminescence were fabricated. Assisted TEM pictures shows the SiGe self-assembly QDs are plate-like. And it showed that the diameters of QDs are in range from 40 nm to 140 nm with the most in 120 nm. Both EL and PL has a wide luminescence peak due to wide distribution of QDs dimensions. At low temperature (T equals 14 K), EL peak has a red shift compared to the corresponding PL peak. Its full-width at half- maximum (FWHM) is about 97 meV, a little smaller than that of corresponding PL peak. The reasons of position and FWHM changes of EL peak from QDs have been discussed.
Photoluminescence measurement on erbium-doped silicon
Hongbing Lei, Qingqing Yang, Haiyan Ou, et al.
Erbium-implanted silicones were treated by lamp-heating rapid thermal annealing (RTA). Two types of erbium-related photoluminescence spectra appear under different anneal temperatures. 750 degrees Celsius annealing optimizes the luminescence intensity, which does not change with anneal time. Exciton-mediated energy transfer model in erbium-doped silicon was presented. The emission intensity is related to optical active erbium concentration, lifetime of excited Er3+ ion and spontaneous emission time. The thermal quenching of the erbium luminescence in Si is caused by thermal ionization of erbium-bound exciton complex and nonradiative energy backtransfer processes, which correspond to the activation energy of 6.6 meV and 47.4 meV respectively.
Deep finlike AlGaAs nanostructure fabricated by CAIBE
Sheng Li Wu, Lijun Wang, Richard C. Tiberio, et al.
We show that very narrow fin-like periodic nanostructure with 0.1 micrometer width, 1 micrometer depth, and a few microns length can be fabricated on AlGaAs using Chemically-Assisted- Ion-Beam-Etching with oxidized AlGaAs as negative mask. This technique may have applications to nanoscale devices fabrication.
Thin Film Optoelectronic Devices
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Numerical study of gain of Er3+-doped LiNbO3 waveguide amplifier
Shufen Chen, Wenjie Lu, Yongbing Qin
A theoretical analysis of amplifier on Er-doped LiNbO3 monomode waveguide is presented. The software package is implemented to simulate the propagation of electromagnetic waves. The modeling is built on the base of two-level energy system neglecting ESA, and the calculation is carried on forward pumping for single pass configuration.
Growth factor of Fe-doped semi-insulating InP by LP-MOCVD
Xuejin Yan, Hongliang Zhu, Wei Wang, et al.
The semi-insulating InP has been grown using ferrocene as a dopant source by low pressure MOCVD. Fe doped semi-insulating InP material whose resistivity is equal to 2.0 X 108(Omega) *cm and the breakdown field is greater than 4.0 X 104Vcm-1 has been achieved. It is found that the magnitude of resistivity increases with growing pressure enhancement under keeping TMIn, PH3, ferrocene [Fe(C5H5)2] flow constant at 620 degrees Celsius growth temperature. Moreover, the experimental results which resistivity varies with ferrocene mole fraction are given. It is estimated that active Fe doping efficiency, (eta) , is equal to 8.7 X 10-4 at 20 mbar growth pressure and 620 degrees Celsius growth temperature by the comparison of calculated and experimental results.
Novel method for fabricating waveguide grating by phase mask technique
Shaojie Ma, Yan Li, Mai Xu, et al.
We report the fabrication of waveguides gratings coupler in photoresist by using a volume holographic gratings and that of the holographic gratings by Red Sensitive Photopolymer at 632.8 nm. The holographic gratings can produce diffracted light of 0 and -1 orders with equal intensity. The two diffracted light beams yield the interference fringe of period in near field, which is as laser sources to expose the photoresist on waveguide.
Digital measurements of propagation loss in optical organic polymer waveguides
Yi Jiang, Zhuangqi Cao, Yingli Cheng
Many conventional methods to detect propagation losses in optical waveguides, such as Cut-Back Method and Prism-Sliding Method, are either destructive or inconvenient. Here we demonstrated a new method -- CCD camera photographing method. A CCD camera was used to take digital photographs of the light streak in the waveguides and the scattered-light intensity distribution is recorded. After fitting the intensity distribution into an exponential attenuate curve, the propagation loss finally can be calculated from the attenuation coefficient of the curve. Compared with other detecting methods, it is more convenient and accurate. In our experiment, samples of polymer waveguides with propagation losses less than 0.5 dB/cm were fabricated.
Optical modulation in ZnSe-ZnS multiple quantum wells
Dali Liu, Gongyu Li, Junqing Fan, et al.
In this paper, the fabrication of a ZnSe-ZnS Multiple Quantum Well (MQWs) with 100 periods of 10 nm ZnSe well and 10 nm ZnS barrier and measurement of its modulating property was reported. The ZnSe-ZnS MQWs are most interesting material and its applications were discussed.
Analysis and simulation of the performances of Si/SiGe HBTs and monolithic integrated preamplifiers of photoreceivers
Lixin Zhao, Chen Xu, Guo Gao, et al.
In this paper, we analyzed the characteristics of the noise, current gain, frequency performance and dynamic range of Si/SiGe heterojunction bipolar transistors (Si/SiGe HBTs) for photoreceivers. They are influenced by the following factors: (1) the doping density, the thickness of the high doped and low doped layers of the emitter, (2) recombination currents in the interface of the emitter-base heterojunction, (3) the germanium (Ge) and Boron (B) content and profile in base region, (4) the collector-base heterojunction barrier effect. Then we gave the device analysis model, noise analysis model and their equivalent circuits of the Si/SiGe HBTs, for simulating and optimizing the performance of Si/SiGe HBTs used in photoreceivers. A novel Si/SiGe HBTs of preamplifiers for photoreceivers has been designed and fabricated. Its current gain (beta) max equals 300, the cut off frequency fT equals 10 GHz and the maximum oscillation frequency fMAX equals 5 GHz. Based on this, we analyzed, simulated and optimized the performances of the preamplifiers of photoreceivers, include the sensitivity, the dynamic range, the transimpedance characteristics, frequency response, and bit rate of the transimpedance preamplifiers of photoreceivers composed of SiGe HBTs, and optimized the design of SiGe HBTs- based monolithic integrated preamplifiers of photoreceivers.
Upconversion luminescence of Tm3+- and Yb3+-codoped pentaphosphate noncrystalline under the pumping of a 798-nm laser diode
When excited into Tm3 3F4 level by a LD at approximately 798 nm, Tm3 and Yb3 codoped pentaphosphate noncrystalline samples emit blue light at 475 nm, which corresponds to transition 1G4 yields 3H6. Although laser is directly absorbed by Tm3+ ions, the upconversion process rely on the codoping of Yb3+ ions. One Tm3+ yields Yb3+ transfer process excites Yb3+ ions, then backward Yb3 yields Tm3 energy transfer excites Tm3 ions from 3H4 to 1G4 level.
Integrated acousto-optic frequency shifter with surface acoustic wave
Bin Zhang, Zhenwu Pan, Bin Mi, et al.
Integrated optical rotation sensor (IORS) is a new type of optical sensors. In this paper, an integrated acousto-optic frequency shifter (AOFS) with surface acoustic wave (SAW) is developed as one of key integrated elements of IORS. The design, fabrication and test of acousto-optic frequency shifter with SAW are presented. The wedge of zinc oxide film on glass substrate is designed as new structure for using in IORS. Experimental results show that the performance of zinc oxide film is stable, the linearity of zinc oxide wedge is suitable for improving Bragg diffraction efficiency, and some good mono-mode performances of planar waveguide are obtained. The frequency shift of 198 MHz plus or minus 0.75 MHz, diffraction efficiency of 8% (at optical wavelength of 0.63 micrometer), and 3 - 5% (at optical wavelength of 1.06 micrometer) are obtained at 1 Watt of electrical power. These experimental results satisfy the main requirements of IORS. High frequency stability is the main specification of RF driving circuits for using SAW AOFS in IORS. In this paper, a new digital scheme based on direct digital synthesis is presented for improving frequency stability.
Design of 4x4 GaAs-GaAlAs carrier-injected total internal reflect optical switch array
Ruimin Yin, Jianyi Yang, Qiang Zhou, et al.
A new scheme of GaAs-GaAlAs total-internal-reflect (TIR) optical switch unit based on bandfilling effect is presented in this paper. Asymmetric Y-branch, which is the essential part of switch structure, is analyzed using beam propagate method (BPM) on three different conditions: index change due to injection, width of injection region and position of injection edge. Unit with two perpendicular output ports is designed according to the numerical results to realized small sized 4 X 4 array which can easily couple with fibers and quickly give off heat.
Upconversion luminescence of ZBLAN:Tm3+,Yb3+ glass pumped by a ~970-nm LD and its concentration effect
Wide wavelength range of upconversion fluorescence at 360 nm, 450 nm, 475 nm, 647 nm, and 800 nm were observed in Tm3+ and Yb3+ codoped ZBLAN glass when pumped by a laser diode at approximately 970 nm. Those emissions are from three metastable states 1D2, 1G4 and 3F4, respectively. Three samples with varying Tm3+ and Yb3+ ion doping were investigated. It was shown that the luminescence intensity, as well as the dependence of intensity on laser power density, vary strongly with rare earth ion concentrations. And the mechanism for the population of 1D2 level is clarified further.
Phenomenon of the second uprising of Yb.Er:ZBLAN upconversion luminescence by the power of a 966-nm pumping laser
Hong Wang, Zhao Hao, Mengxia Li, et al.
In the study of Rare-earth upconversion luminescence, it is always a key factor to efficiently increase the luminescence efficiency. Some exciting results have been achieved by the method of sensitization of codoped rare-earth ions. The high upconversion efficiency has been achieved by the very effective way of using the Yb3+ ions' 2F5/2 energy level as the intermediate level to transfer energy to many other rare-earth ions. Due to the strong absorption of Yb3+ ions between the wavelength of 900 nm to 1000 nm, the population can be accumulated largely on the 2F5/2 energy level and it becomes possible to transfer energy to higher levels. In recent years, the study of the upconversion luminescence of Ho3+, Er3+, Pr3+ sensitized by Yb3+ shows that Yb3+ can cause quench at the same time with sensitization. So the codoped system of Yb3+ + R E (rare-earth ions) has very complex luminescence mechanism and in most situation the upconversion channels are not single or single direction. The study of the sensitization and quench is very important just because these complexities. Since the diode laser in 900 nm to approximately 1000 nm has developed quite well, it becomes possible to use mono-frequency diode laser to pump upconversion laser and fiber laser. In this paper, the upconversion luminescence of Yb(0.3)Er(0.3):ZBLAN glass induced by 966 nm diode laser was studied. Base on the experiment data, these results are calculated by the rate equation: when the cross energy transfer P between Yb3+ and Er3+ ions is quite weak, the upconversion luminescence become saturated gradually by the increase of the pump laser power; when the P is quite strong, it will cause a steep uprising of the luminescence before the saturation. This is the phenomenon of second uprising by the laser power that observed in the experiment.
High-power superluminescent diodes
Yi Qu, Xin Gao, Baoshun Zhang, et al.
A high power superluminescent diode (SLD) is developed on the basis of the terraced substrate inner laser diodes. The device is made of the characteristic of LPE of crystal on the non- planar substrate. The device's output power before assembled is 7 mW under operating current 150 mA. The wavelength is about 860 nm. The half width of the spectrum is 23 nm. The device is coupled with fiber (NA equals 0.23, D equals 50 micrometer). The coupling efficiency is about 30%. The pigtail fiber maximum output power is 2 mW.
Device and System Application Using Integrated Optoelectronic Circuits
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Optically controlled multiple-beam-forming network for phased-array radar
Yixin Wang, Shunan Zhong, Xiaowen Xu, et al.
Multiple beam forming is widely used in modern RADAR system, and it can be accomplished at radar radio frequency by using integrated opto-electronics device and optical fiber distribution and time delay network. This paper describes a receiving system of multiple beams by using integrated opto- electronics device, optical fiber distribution network and optical fiber time delay line. When the opto-electronics switch with controllable extinction ratio and optical microwave phase shifter which can make a good control of phase shifting are applied in this system, the complex weight coefficient can be effectively adjusted, and the adaptive multiple beam forming networks can be established. With the optically controlled multiple beam forming technology, the weight and volume of the system can be reduced and the anti- interference ability and stability of temperature be increased. In addition, the channel numbers can also be increased, which is especially beneficial to large phased arrays system.
High-speed multiplication for digital optical computing
Naxin Wang, DeGui Sun, Zhao-Heng Weng
The modified singed-digit (MSD) number system can offer parallel addition and subtraction of any two numbers, while carry propagation constrained only between two adjacent digits. Basing on MSD addition, we develop parallel algorithms for high-speed multiplication (MSD multiplication) in this paper. The simultaneous generation of all the partial products and the pairwise addition of the partial products are unique features of this MSD multiplier. Optoelectronic butterfly interconnection (OEBI) network matches well with the multiplier presented here.
Nondestructive measurement for impurity concentration inserted in multilayer inhomogeneous material
In this paper, for the solid sample composed of three layers in which the thermal property is inhomogeneous and tho optical-absorption coefficient is varied, a new and effective numerical method is proposed, and it is used to nondestructively reconstruct the depth distribution of optical-absorption coefficient in multilayer inhomogeneous material through by the photothermal signal which are measured on the surface of a sample with the photothermal method. By means of the relation between absorption coefficient and nitrogen concentration, we may obtain the spatial distribution of the nitrogen concentration in a GaP:N sample. Inverse results by experimental data show that the performance of the approach at p/n junction is better.
Function testing and failure analysis of integrated circuit chip using laser probe
Xiaojian Tian, Maobin Yi, Daming Zhang, et al.
Introduced the construction of the experiment system of the laser probe measurements based on electro-optic sampling technique. Analyzed the relationship between the width of the optical pulses and the signal noise ratio of detection. The function of different stage circuit internal to the high-speed dynamic divider circuit chip have been measured with the double-frequency phase sweeping technique. A detail analysis about the chip failure have been given.
Design and fabrication of GaAs-integrated optical chip used in a fiber optic gyroscope
Jin Li, Jianyi Yang, Weiqin Zhou, et al.
In this paper, we present the design, fabrication and measurement of the GaAs integrated optic chip which is used in fiber optic gyroscope system. The integrated optic chip consists of the single mode waveguide, Y-branch power divider, polarizer and phase modulators. According to the design results, we succeed in fabricating the chip on GaAs/GaAlAs single-heterostructure epitaxial materials which are grown by MBE. The total size of the chip is as small as 10 X 0.5 mm2. The device has been being measured. We have got two light spots outputting from the device by the measuring system. And the half wave voltage of its phase modulator is about 10 V.
Ray optics formation theory of geodesic lenses
Jingping Zhu, Kangyan Hu, Tiantong Tang
The expressions of cardinal point site, principal plane and focal length of geodesic lenses are derived from ray optics. According to the obtained characteristics of focal points and principal planes, the geometry graphic imaging formation principles are presented to get the object-image-relation of geodesic lenses.
Novel optoelectronic sorting network with recirculating architecture
Yuan Lin, Mingcui Cao, Fengguang Luo, et al.
In this paper, a novel optoelectronic sorting network with recirculating architecture is presented. It can realize fast sorting with large number of data in low spatial complexity. This is achieved by using parallel optical interconnect (implemented by a 1 X 2 binary phase grating), introducing a recirculating architecture, and using the array of Compare- and-Exchange (C&E) implemented by CMOS-SEED hybrid integrated circuit.
Stability of GaAs photocathode
Kan Mi, Xun Hou
Present work focuses on the mechanism of the stability of GaAs NEA photocathode. A series of measurements was made in various operation conditions in the Ultra-high-Vacuum (UHV) System, experimental curves of the quantum efficiency of GaAs NEA photocathode decay vs. time with different residual gas in the Ultra-high-Vacuum (UHV) System were offered. In addition, a model was presented to describe the stability of GaAs NEA photocathode after activated by Cs,O in vacuum chamber. Furthermore, theoretical research has been carried out using Monte Carlo method to simulate the quantum efficiency decay of GaAs NEA photocathode, the calculated lifetimes showed good agreement with the experimental results. The mechanism of stability of GaAs NEA photocathode was also discussed. Some methods that were used to improve the lifetime of GaAs NEA photocathode was suggested.
GaAs 1x4 optical power splitter
In this paper, an optical power splitter based on MMI coupler in GaAs/GaAlAs heterostructure materials is fabricated. The epitaxial materials are grown by MBE. The dry etching process is applied to fabricate the ribs in this device. The measuring results are presented.
Harmonic diffractive optical element and its application
Liping Zhao, Minxian Wu, Guofan Jin, et al.
Compared with other kinds of diffractive optical elements (DOEs), the harmonic diffractive optical element (HDOE) is analyzed, and some important results including its dispersion are deduced and presented in this paper. Its inherent advantages and characteristics are analyzed and concluded, and then several applications including imaging in the wide wavelength band, multicolor optical Fourier transform system, and multicolor scanning system are suggested. The harmonic diffractive optical elements or systems have small volume and strong potentials in the applications of achromatic multi- wavelength multi-order diffraction, so it is promised that HDOE will be useful in the field of integrated photo- electronics.
128x128-element silicon microlens array fabricated by ion-beam etching for PtSi IRCCD
Xinyu Zhang, Xinjian Yi, Miao He, et al.
A silicon refractive microlens array mounted on a 128- X 128-element PtSi IR CCD focal-plane architecture is fabricated using a multiple-process, including photolithography, heat treatment, and argon ion beam etching techniques. The optical filling factor of PtSi IR CCD with refractive microlens array is more than 95 percent. The focal length of the square-base arch silicon microlens is about 90 micrometer. Both the scanning electron microscope and the surface style measurement are carried out to determine the dimensions and the surface morphology of silicon refractive microlens. The matching properties between the preshaped photoresist mask and silicon substrate during argon ion beam etching are given. The techniques utilized can be applied to fabricate microtips array and microplateforms (circle microtips) array.
Silicon field emitter microtip array fabricated by ion-beam etching
Xinyu Zhang, Xinjian Yi, Miao He, et al.
A relatively simple and effective method to fabricate 128- X 128-element emission microtips array on the surface of silicon substrate is proposed. The method mainly involves photolithographic process and argon ion beam etching. Typical center-to-center spacing of microtips fabricated is 50 micrometer, typical height is about 11 micrometer, and typical sharpness is about 9 sr. The scanning electron microscope analysis and the surface style measurement are presented for the surface morphology of two kinds of silicon emitters microtips (square-based pyramidal microtips and circle-based cone microtips) and circle microtips array. The experiments show that the technique used can be applied to fabricate silicon emitter microtips array and circle microtips array of larger area.
Thin Film Optoelectronic Devices
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Silicon opto-FET coupled to waveguides for integrated optical microsystems
Dana Cristea, Florea Craciunoiu
Integrated optics on silicon gives the opportunity to obtain microsystems for optical communications or sensor applications on one silicon chip. In all types of applications it is necessary to connect the waveguides to the photodetectors to transform the optical signal in an electrical signal. We have designed an opto-FET with a special structure that allow the optical coupling to a waveguide. A 3-D model was developed for the system: opto-FET-coupler-waveguide. The model takes into account two effects of the incident illumination: the variation of channel conductivity due to the carrier generation; the variation of channel depth due to the photovoltaic effect across the channel-gate junction. Also we studied the channel depth variation along the channel length (due to the potential variation) and along the channel width (due to the exponential decrease of optical power). The most important conclusion of the model is: in case of leaky-wave coupling of the opto-FET to a waveguide, the dependence of the photocurrent on optical power is practically linear, while in the case of uniform illumination it is logarithmic. The model was verified on a circuit integrated on silicon.
Thin Film Optoelectronic Material and Simulation
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Phase conjugation of picosecond optical pulses in semiconductor optical amplifiers
J. M. Tang, Keith Alan Shore
A numerical investigation of the four-wave mixing efficiency of picosecond optical pulses in semiconductor optical amplifiers is performed. Special attention is paid to the influence of probe depletion (PD) and cross-gain modulation (XGM) on four-wave mixing (FWM) efficiency. It is shown that variations in FWM efficiency induced by both PD and XGM can be significantly enhanced by shorter pulsewidth, higher pulse energy and smaller pump-probe frequency detuning, and that the variation of FWM efficiency caused by PD is symmetrical with respect to negative and positive frequency detunings, while the FWM efficiency change due to XGM exhibits an asymmetric lineshape.
Device and System Application Using Integrated Optoelectronic Circuits
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Board-level optical clock signal distribution using Si CMOS-compatible polyimide-based 1- to 48-fanout H-tree
Linghui Wu, Bipin Bihari, Jianhua Gan, et al.
Si-CMOS compatible polymer-based waveguides for optoelectronic interconnects and packaging have been fabricated and characterized. A 1-to-48 fanout optoelectronic interconnection layer (OIL) structure based on Ultradel 9120/9020 for the high-speed massive clock signal distribution for a Cray T-90 supercomputer board has been constructed. The OIL employs multimode polymeric channel waveguides in conjunction with surface-normal waveguide output coupler and 1-to-2 splitter. A total insertion loss of 7.98 dB at 850 nm was measured experimentally.
Thin Film Optoelectronic Material and Simulation
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Modeling and design of waveguide-coupled single-mode microring resonators
Mee Koy Chin, Seng Tiong Ho
We discuss a first-order design tool for waveguide-coupled microring resonators based on an approximate solution of the wave propagation in a microring waveguide with micron-size radius of curvature and a large lateral index contrast. The model makes use of the conformal transformation method and a linear approximation of the refractive index profile, and takes into account the effect of waveguide thickness, dispersion, and diffraction. Based on this model, we develop general design rules for the major physical characteristics of a waveguide-coupled microring resonator, including the resonance wavelength, the free spectral range, the coupling ratio, the bending radiation loss and the substrate leakage loss. In addition, the physical model provides insights into alternative coupling designs that significantly increase the coupling length and reduce or eliminate the dependence on a narrow air gap in the waveguide-coupled microring resonator. We present two examples, one using a phase-matching parallel waveguide with a smaller width than the ring waveguide, and the other using a vertical coupling structure.