This PDF file contains the front matter associated with SPIE Proceedings Volume 10244, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Coherent optical systems face two main categories of linear impairments, chromatic dispersion (CD) and polarization mode dispersion (PMD). Both CD and PMD will create large inter-symbol interference (ISI). This paper focuses on M-quadrature amplitude modulation (QAM) signal detection directly using Echo State Networks (ESN) technique for compensating (residual CD and PMD) dispersion of coherent optical systems. The proposed approach can estimate directly the input sequence at the coherent receivers, without getting the electronic equalizer coefficients and estimating optical channel impulse response. In addition, the proposed approach can guarantee a convergence within a short data packet.

Aimed to establish a Raman lidar system with high-reliability and high anti-interference performance, an newly all-fiber spectroscopic Raman lidar system was proposed for atmospheric water vapor measurement, in which optical fiber couplers, fiber band-width filters and fiber F-P filters constitute the all-fiber spectroscopic system. On the basis of the design of fiber F-P filters and its transmission analysis, the series connection of optical fiber coupler is designed as fiber optics splitter, which is not only to obtain fiber coupling of the input and output of lidar returns, and also to achieve the optimal energy output ratio at three fiber channels. Furthermore, fiber band-width filters are proposed to replace the dichroic mirrors, and the structure of fiber band-width filters and fiber F-P filters is to constitute the secondary cascade filter system, achieving the fine extraction of interested spectrum and high rejection rate to elastic scattering signals. Preliminary test results indicated that, the energy at the three output ports is %sim;5: 2.5: 2.5, and the two fiber band-width filters are provided with the central wavelength of 606nm and 660nm, the bandwidth of 20nm, and the out of band inhibition of >0.5%, which met the design requirements. The design and results will provide a reliable basis for the integration and experiment of the subsequent all-fiber spectroscopic system.

In this paper, a novel wavelength division multiplexing (WDM) access network has been proposed. Here, the optical protection modules (OPMs) and erbium-doped optical fiber amplifiers (EDFAs) employed in both the central office (CO) and the remote node (RN) enable this WDM access network with broadcasting services not only to achieve high reliability under long-distance transmission but also to scale up easily in the future. Also, this scheme has the feature of Rayleigh Backscattering mitigation. The analysis shows good performance of this network.

Diffractive optical elements (DOEs) can realize beam shaping with higher light efficiency, strong flexibility of diffraction pattern, and is suitable to be used in optical interconnections to split beams. In order to increase the intensity uniformity of the split beams, a hybrid algorithm merging Gerchberg-Saxton (GS) algorithm with gradient method is presented based on the sampling rule different from the existing optimization algorithms. By controlling N extra points with zero amplitude besides the original N sampling points on the input plane, and finally the sampling pitch on the Fourier plane is half of that of the conventional sampling rule. Then the N extra points on the Fourier plane will be controlled. Finally spot array with high intensity uniformity can be realized with the proposed algorithm. Simulation results demonstrate the good performance of the proposed algorithm.

Our study proposes a method of monitoring polarization mode dispersion (PMD) under the influence of chromatic dispersion (CD) and optical signal-to-noise-ratio (OSNR) in the two-dimensional phase diagram, using delay sampling by two-dimensional phase diagram. The result shows that PMD at range of 5ps √km to 37ps √km can be effectively monitored from the interference of CD and OSNR.

According to the transverse intensity distribution of the TEM00 Gaussian light field and character of an irradiance redistribution element, we proposed a novel method, which has the advantages of high light-energy-utilization-ratio (LEUR). The current laser communication (LASCOM) antenna frequently employs the Cassegrain reflective optical structure, in which the secondary mirror will introduce a center obscuration, leading to high ratio of transmitting power loss. To solve this problem, we make the transmitting beam pass through double convex axicons. The Gaussian peak of incident light coming into the central part of such element, will go out from near the peripheral part of the second axicon, and the edge part of Gaussian beam will go out from the central part. When the changed beam passes the Cassegrain structure, the utilizing efficiency will be raised obviously. In the paper, on different obscuration rate, the LEURs of LASCOM system before and after using the axicons are compared. In addition, the far-field intensity distribution of the laser beam changed by the axicon pair and transmitted by the antenna is calculated. The simulation result shows that the LEURs of antenna with and without an axicon pair are 91.7% and 28.9% on a Line obscuration ratio of 1/4. After a propagation of 1000 km, the far-field energy distribution of the hollow beam translated by the high LEUR antenna is closer to a flattop beam than that for the common Gaussian beam.

Clock synchronization is crucial for a practical continuous-variable quantum key distribution system to precisely get the measurement result. Three different synchronization schemes for continuous-variable quantum key distribution system are presented to demonstrate the optimal scheme. The performance of synchronization scheme is evaluated by measuring the excess noise which is the critical parameter for the continuous-variable quantum key distribution system. The experiment results show that distilling the synchronization signal from the local oscillator has the simplest physical implemention and superior effect of synchronization, but a stronger local oscillator is required. Transmitting synchronization signal and quantum signal in the same fiber by wave-length division multiplex is also a fine way to provide stable clock when we take no account of the phsical device and wave-length source.

The fine tracking system is important to improve the performance of orbital angular momentum (OAM) space optical communication system. In order to improve the accuracy and stability of the centroid algorithm, this article proposes a modified algorithm to detect the center position of OAM light beam. The modified algorithm firstly takes a binary-conversion with the threshold based on the intensity profile of OAM beam, and then calculates the center position of the light spot using centroid algorithm. The threshold for binary-conversion of Laguerre-Gaussian (LG) beam is obtained by theoretical analysis and numerical calculation. The accuracy, stability and complexity of the modified algorithm are studied by numerical simulation. The results show that the new algorithm, compared with the centroid algorithm, has 2 orders of magnitude higher in computing accuracy and 3∼4 orders of magnitude higher in stability. However, the computing time has increased by about 1.5 times compared with the centroid algorithm.

Optical data center networks are becoming an increasingly promising solution to solve the bottlenecks faced by electrical networks, such as low transmission bandwidth, high wiring complexity, and unaffordable power consumption. However, the optical circuit switching (OCS) network is not flexible enough to carry the traffic burst while the optical packet switching (OPS) network cannot solve the packet contention in an efficient way. To this end, an improved switching strategy named OPS with multi-hop Negative Acknowledgement (MPNACK) is proposed. This scheme uses a feedback mechanism, rather than the buffering structure, to handle the optical packet contention. The collided packet is treated as a NACK packet and sent back to the source server. When the sender receives this NACK packet, it knows a collision happens in the transmission path and a retransmission procedure is triggered. Overall, the OPS-NACK scheme enables a reliable transmission in the buffer-less optical network. Furthermore, with this scheme, the expensive and energy-hungry elements, optical or electrical buffers, can be removed from the optical interconnects, thus a more scalable and cost-efficient network can be constructed for cloud computing data centers.

A hybrid multiplexer (HMUX) for wavelength/mode-division (WDM/MDM) based on photonic crystals (PCs) is proposed. The device can realize TE0 and TE1 modes multiplexing at wavelengths of 1550nm and 1570nm. According to quasi phase matching, a structure with an asymmetrical parallel waveguide (APW) was used to achieve mode conversion. The transmittance of the TE0 mode at wavelengths of 1550nm and 1570nm are 98.4% and 96.3%, the corresponding insertion loss are 0.07dB and 0.16dB respectively. The crosstalk of the TE0 mode at wavelengths of 1550nm and 1570nm are -27.66dB and -27.32dB respectively. The transmittance of the TE1 mode at wavelengths of 1550nm and 1570nm are 95.8% and 93.9%, the corresponding insertion loss are 0.19dB and 0.27dB respectively. The crosstalk of the TE1 mode at wavelengths of 1550nm and 1570nm are -38.73dB and -38.9dB respectively. The PC-based HMUX has great performance, and it will have great application potential in future ultrahigh-speed and large-capacity communication systems.

We present a quarter-wave plate composed of two pairs of cross-shaped elliptical nanoatennas. This setup can transform linearly polarized incident light to circular polarized light at a wavelength of 862nm. The cross-shaped elliptical configuration can control the amplitude and phase of incident light. By the modulation of the elliptical size, equal amplitude and specific phase difference can be obtained in orthogonal directions. Furthermore, as a quarter-wave plate, this configuration is not sensitive to the polarized direction of the linearly polarized incident beam. In order to verify the designed metasurface, numerical simulation were performed using the finite difference time domain method. Our results may benefit novel photonics devices design such as polarization manipulation, optical sensing, optical detecting, and photonic integration.

In this paper, an active ring-coupled Mach-Zehnder interferometer (arcMZI) for rotation sensing is proposed. Theoretical resolution formula of this arcMZI gyroscope was deduced by using of transfer matrix method and noise analysis model. The simulation result shows that the theoretical maximum sensitivity of arcMZI gyroscope can be enhanced at least two orders of magnitude compared with the single-bus resonator (SBR) gyroscope for the same footprint and effective loss after equivalent optimization. The arcMZI gyroscope could be of great potential to meet the tactical demands of future inertial navigation.

We theoretically analyze the characteristics of scale factor in frequency sensitive integrated optical gyroscope consisting of a ring resonator coupled with double ring resonators. The impact of through coupling coefficients is investigated to decide the optimal parameters located at 0s^-1 for improving the scale factor. It demonstrates that the scale factor enhancement in this frequency sensitive optical gyroscope, without increasing the overall footprint, can be improved compared with conventional single ring resonator gyroscope and presents the characteristic of better performance within low-rate range. It implies a broad prospect in highly integrated on-chip applications, especially in aeronautic and astronautic area.

Target detection is one of most important applications in remote sensing. Nowadays accurate camouflage target distinction is often resorted to spectral imaging technique due to its high-resolution spectral/spatial information acquisition ability as well as plenty of data processing methods. In this paper, hyper-spectral imaging technique together with spectral information divergence measure method is used to solve camouflage target detection problem. A self-developed visual-band hyper-spectral imaging device is adopted to collect data cubes of certain experimental scene before spectral information divergences are worked out so as to discriminate target camouflage and anomaly. Full-band information divergences are measured to evaluate target detection effect visually and quantitatively. Information divergence measurement is proved to be a low-cost and effective tool for target detection task and can be further developed to other target detection applications beyond spectral imaging technique.

Waveform sampling LiDAR is a hot topic in LiDAR technique due to its high precision geodesy and multi-layer target detection ability. Especially, the LiDAR systems applying streak tube have encouraging application due to their special properties about high-sensitivity and full waveform sampling ability. This paper describes a kind of LiDAR system applying the full waveform sampling stripe principle array. Basing on the planar fitting of square object, the elevation error of points cloud got from flight experiment is analyzed. The statistical properties of elevation error are got.

To prevent tragic disasters caused by terror acts and warfare threats, security check personnel must be capable of discovering, distinguishing and eliminating the explosives at multiple circumstances. Standoff technology for the remote detection of explosives and their traces on contaminated surfaces is a research field that has become a heightened priority in recent years for homeland security and counter-terrorism applications. There has been a huge increase in research within this area, the improvement of standoff trace explosives detection by optical-related technology. This paper provides a consolidation of information relating to recent advances in several key problems of, without being limited to one specific research area or explosive type. Working laser wavelength of detection system is discussed. Generation and collection of explosives spectra signal are summarized. Techniques for analysing explosives spectra signal are summed up.

Electrical speckle shearing pattern interferometry (ESSPI), being an interfering measurement technology, has been used to measure harmonic vibration deviating from object plane with time-average method or stroboscopic method. Time-average is generally used in qualitative analysis of vibration for the contrast of stripes in the electrical speckle shearing interfering images rapidly decreased with the addition of stripe-levels. Stroboscopic method can be used to measure instant vibration distribution. The specific measuring method and theory of stroboscopic method in electrical speckle shearing pattern interferometry are analyzed and corresponding mathematical model is set up. The vibration measuring system based on ESSPI and stroboscopic method is designed. The experiment results with the system are shown in the paper to prove the availability of stroboscopic method and capability of system to measure vibration.

As athermal design is an important issue in the field of infrared optical system design, this paper originated a test procedure on athermal design effect based on optical transfer function gauge. In this procedure, we let the optical system under test automatically focus first, then record its focus position under different temperatures, finally get the relative defocusing amount of the optical system under test under different temperature. This paper also developed a test system of a kind of athermal design effect, introduced its system composition and its working principle of measuring the defocusing amount, and gave the experiment results. The results suggest that it can focus fast, its repeatability is good, and it can resist noise interference with high precision.

This paper presents a novel microscope spray droplets detecting technique based on image processing method, which is applied to an experimental measurement performed on a flat fan atomizer nozzle. The droplets images are detected by an image acquisition system. The raw images are pre-processed to enhance the images and avoid the illumination unevenness effect. An image restoration method based on iterative blind deconvolution is applied to improve the quality of the blurred image due to droplets movement and defocus. Circle Hough transform and the least square method are applied to find the droplet contour in the image, and the droplets diameters are calibrated and counted. A criterion is presented to avoid repeated statistic problem. The measurements of water spray droplet size distribution from a small flat fan nozzle atomizers are taken and the experiment results are analyzed.

X-ray Absorption Spectroscopy (XAS) was been applied for the material recognition in this paper. Twelve kinds of plastics were selected as specimens. Each specimen was tested for 100 times by different operators for data processing. Seventy sets of spectral data of each specimen were randomly selected as training set and the other 30 sets were selected as testing set. Training set was calculated with Principal Component Analysis (PCA) to get the first four Principal Components, which totally explain 99% of the original spectrum. The first four Principal Components were built plastic classification model respectively through K-Nearest Neighbor (KNN) and Support Vector Machine (SVM) methods. The classification accuracy reached 89.22%-98.17%. Experimental results demonstrate that organics could be recognized by XAS. It shows that the X-ray absorption spectroscopy contains the potential of other organics recognition or even organisms.

This paper focuses on the stabilization problem for the floated inertial platform experimental system. Based on the moment analysis of the platform and the mode of the main moment, the dynamic equation of the stabilized platform rotating around its center is derived in consideration of some disturbances. To solve the system model uncertainty, measurement noise, three-axial coupling and unmodeled disturbances, the Auto Disturbances Rejection Controller (ADRC) is proposed. In addition, the time delay problem, caused by system wireless transmission, is addressed using an improved ADRC controller. Three-axial stabilized control system model of floated inertial platform experimental system is built by MATLAB/SIMULINK. Simulations indicate that the ADRC controller is better than the traditional PID controller. This controller can stabilize the platform more quickly, more accurately, more robustly and without overshoot. Improved Smith predicting ADRC controller can eliminate the influence of transmission time delay of the system to realize the stability control real-timely. By virtue of this improved controller, this platform can provide an effective inertial reference for the vehicle.

In the air, Mach-zehnder interference system was set up to study the plasma expansion process of single crystal silicon induced by millisecond pulsed laser. Electron density is the main parameter of laser plasma characteristics. Calculation electron density of silicon plasma based on the relationship between the FWHM of Stark broadening of spectral line and the electron density. Experimental results show that: The existence material splash phenomenon is existence in silicon plasma generated by millisecond laser, the long pulse laser interaction with material has the thermal effect. Silicon plasma emission spectrum is strong in the distribution of the continuous spectrum, the discrete series of atoms and ions are superimposed on it. With the increase of the laser energy density, the electron density of the plasma increases.

LED is a kind of reliable source of LCD backlight. The characteristics of LED determine the color gamut and brightness of LCD TV. At present, the mainstream of white LED mainly uses blue chip coated with YAG phosphor to get white light, which can only guarantee the color gamut to 72%NTSC. Based on the color characteristics of backlight module, the method of calculating the color gamut of backlight module are introduced in detail. Coating blue chip by different kind of phosphors, a new LED backlight for LCD TV is developed. The color gamut is improved to more than 80%NTSC or more. At the same time, through the optimization of combination of blue chip with selected green phosphor and red phosphor excitation peak, this white LED solution can get the different color gamut and the highest color gamut, which will be 88%NTSC at most. This technique has been applied to a LCD TV.

For space target photoelectric detection, the false-alarm problem is analyzed using the radiation theory. Firstly, the mathematic equations are deduced about the radiation of space target and its background; Secondly, the numerical calculation is carried out by taking U.S. KH-12 as research object, and the false-alarm problem is analyzed. The results show that: the main false-alarm sources are sun, earth-atmosphere system, moon and Venus. This work can provide theoretical reference for the design of space-based all-weather imaging system.

Most existing works on compressive imaging require electronic devices to perform the spatial optical modulation (SOM) or sparsifying transform (ST), which increase the cost and power consumption in field application. For the implementation of compressive imaging with a cheaper cost, the sensing strategy with blocking random pulse sampling (BRPS) is proposed. Instead of using the SOM and ST required by conventional technologies, the BRPS sampling can be achieved by the random unit-pulse in spatial domains. For actual application, the BRPS can be realized by address controlling for CMOS image sensors with a low resolution. For BRPS sampling, the image can be reconstructed by TVAL3. Experimental results show that, the BRPS achieves better reconstruction than conventional compressive sensing with Gaussian random matrix. Therefore, the BRPS contributes to the implementation of compressive sensing with low cost, low power consumption, less memory requirement, and better reconstruction.

A distributed fiber sensor based on Rayleigh scattering is described which converts vibration-induced optical phase changes into optical intensity variations by using modulated dual-pulses injected into sensing fiber. Phase generated carrier algorithm is used to permit arctangent operation to demodulate the phase information along the sensing fiber. The demonstrated sensor is capable of probing dynamic acoustic or vibration disturbances over 10km of sensing length with spatial resolution of 6m and large signal to noise ratio. The background noise of our system is estimated about 1×10^-3 rad/√Hz.

One of the most important qualifications of laser range finder is the ranging distance. The ranging distance of laser range finder is usually supplied with a atmosphere condition. To reach the qualification of ranging distance, the manufacturers always increase the laser emitting power which the laser range finders can work not only in the ranging distance. It is important to find the real ranging distance in different visibility especially for military application. The maximum ranging distances in different visibility were discussed in the paper. First, the power of different types of laser range finder was got by experiment. The power of two models of laser range finder was got, and the power of same model but two serial numbers was obtained. Then, the fluctuation regularity was discussed. Then, the maximum ranging distances in different visibility were got by numerical simulation. The maximum ranging distances of laser range finder with same model but two serial numbers were calculated. The figures of maximum ranging distances varying with visibility were obtained. It was showed that the maximum ranging distances of laser range finder with same model but two serial numbers were different.

The Fe/Al thermite was made as bulk material. Mixed proportion with liquid energetic colloid, the Fe/Al thermite was made to be collid Fe/Al thermite combustible agent. Then, combustion test sample was got. The combustion process and the infrared radiation characteristic of colloid Fe/Al thermite was experiment by thermal infrared imager. It was showed that collid Fe/Al thermite combustible agent had better infrared radiation characteristic. It could be as based agentia of infrared decoy with the characteristic of persistent and wide spectral range.

Polarization difference imaging can improve the quality of images acquired underwater, whether the background and veiling light are unpolarized or partial polarized. Computational polarization difference imaging technique which replaces the mechanical rotation of polarization analyzer and shortens the time spent to select the optimum orthogonal ǁ and ⊥axes is the improvement of the conventional PDI. But it originally gets the output image by setting the weight coefficient manually to an identical constant for all pixels. In this paper, a kind of algorithm is proposed to combine the Q and U parameters of the Stokes vector through pixel-level image fusion theory based on non-subsample contourlet transform. The experimental system built by the green LED array with polarizer to illuminate a piece of flat target merged in water and the CCD with polarization analyzer to obtain target image under different angle is used to verify the effect of the proposed algorithm. The results showed that the output processed by our algorithm could show more details of the flat target and had higher contrast compared to original computational polarization difference imaging.

CMOS APS sensors suffer from the SNR reduction caused by the decrease in integration time, especially under the case of low light condition and high relative velocity between objects and sensors. In this paper, a new APS circuits architecture by which TDI function is implemented in the analog voltage domain is proposed to overcome this problem. Time delay integration operation is a straightforward method comes from good old CCD sensors in which signals are added in charge packages with low noise. In this design TDI is mainly achieved by the switch capacitor accumulators and corresponding timing sequences implemented by digital logic on chip. The main noise source especially come from analog sample hold capacitors and OPA are analyzed. The offsets and FPNs are reduced by auto-zero operation and double difference sampling. A 16x128 3T TDI pixel arrays has been taped out by CSMC 0.5 um technology. And finally from the simulation results, a 10dB/dec SNR increase in terms of TDI level has been achieved under low light condition.

In order to detect miRNA quickly, we designed a new portable device for the rapid detection of miRNA, using Opto-electronic detection technology, marking miRNA and isothermal rolling circle amplification and detecting markers which excite fluorescence intensity, the recognition system of characteristic fluorescence analysis was established. By changing the excitation light intensity, miRNA reagent concentration and other parameters, we arrive at the conclusion that there is the linear relationship (R2=0.9947) between miRNA concentration and fluorescence intensity when the miRNA concentration range the instrument can measure is in the range of 0.01-0.1mol and the lowest values measured by the instrument in theory is 7 copies.

Traditional second-order correlation reconstruction method required a large number of measurements, in which not only the quality of reconstructed image was poor but also didn't meet the real-time requirements. We combine the total variation with the compressive sensing method to reconstruct the object image in ghost imaging. The paper describes the basic structure of objective function based on total variation regularization and the corresponding compressive sensing recovery algorithm, and take a comparison with the gradient projection based compressive sensing algorithm about the recovery performance. The simulation results show that compressed sensing algorithm based on total variation regularization has a better compared reconstruction performance than algorithm based on gradient projection algorithm in ghost imaging system. Then apply the above algorithms to experimental data of ghost imaging experiment, and finally got the reconstructed images of the target image. The results once again demonstrate the effectiveness and feasibility of the algorithm based on total variation.

For mastery of infrared radiation characteristics and flow field of exhaust plume of twin engine nozzles, first, a physical model of the double rectangular nozzles is established with the Gambit, and the mathematical model of flow field is determined. Secondly, software Fluent6.3 is used to simulated the 3-D exterior flow field of the twin engine nozzles, and the datum of flow field, such as temperature, pressure and density, are obtained. Finally, based on the plume temperature, the exhaust plume space is divided. The exhaust plume is equivalent to a gray-body. A calculating model of the plume infrared radiation is established, and the plume infrared radiation characteristics are calculated by the software MATLAB, then the spatial distribution curves are drawn. The result improves that with the height increasing the temperature, press and infrared radiant intensity diminish. Compared with engine afterburning condition, temperature and infrared radiant intensity increases and press has no obvious change.

This paper presents a segmented X-ray spectrum detection method based on a layered X-ray detector in Cadmium Telluride (CdTe) substrate. We describe the three-dimensional structure of proposed detector pixel and investigate the matched spectrum-resolving method. Polychromatic X-ray beam enter the CdTe substrate edge on and will be absorbed completely in different thickness varying with photon energy. Discrete potential wells are formed under external controlling voltage to collect the photo-electrons generated in different layers, and segmented X-ray spectrum can be deduced from the quantity of photo-electrons. In this work, we verify the feasibility of the segmented-spectrum detection mechanism by simulating the absorption of monochromatic X-ray in a CdTe substrate. Experiments in simulation show that the number of photo-electrons grow exponentially with the increase of incident thickness, and photons with different energy will be absorbed in various thickness. The charges generated in different layers are collected into adjacent potential wells, and collection efficiency is estimated to be about 87% for different incident intensity under the 40000V/cm electric field. Errors caused by charge sharing between neighboring layers are also analyzed, and it can be considered negligible by setting appropriate size of electrodes.

On account of the uncertain factors caused by the uneven performance and precision of the measurement equipment, the complex and changeable environment and climate for flight in optical tracking measurement in space TT&C networks, the paper presents a method using the variance theory to evaluate the dynamic uncertainty of single optical measured exterior trajectory parameters, in order to figure out the transmission sensitivity coefficients of uncertainty, and to fuse trajectory parameters according to the uncertainty transmission law. The calculation and analysis based on actual combat mission data showed that the method can implement data fusion in trajectory layer. And the method had been proved in practical applications. This method not only expands the technique of comprehensive data processing but also provides technical support for the use of decision-making data.

The temperature-dependent polarization error occurred in the silica waveguide ring resonator (WRR) is a major factor that limits the long-term performance of resonator integrated optic gyro (RIOG). In this paper, the temperature characteristics of transmissive silica WRR are successfully measured using the experiment system and analyzed in detail by us. According to the experiment results, we accurately calculate the temperature-induced refractive index and birefringence variation coefficient of silica waveguide, and we have found that the interference dip and peak of resonance curves will appear alternatively in the period of temperature fluctuation, which had not be shown before.

A narrow linewidth laser composed of an Erbium doped distributed feedback fiber laser (DFB-FL) and an all-single-mode-fiber amplification structure is proposed. The cavity of the DFB-FL is a phase-shifted grating in the Erbium doped fiber and fabricated by ultraviolet laser inscribing and phase mask dithering. A master oscillator power amplifier in all-single-mode-fiber structure is pumped by the residual pump laser from the DFB-FL. The amplified distributed feedback fiber laser with a 57dB signal-to-noise ratio has a linewidth of 2 kHz with low phase noise. The systematic tests about laser linewidth and phase noise are carried out. The results show that these characteristics are comparable to other commercial narrow linewidth laser products. As a stable narrow linewidth laser source, it is attractive and useful in applications in the distributed sensing and the interference sensing fields.

As an important and efficient method of particles size measurement, laser scattering has attracted great interest in the last decades. The sheath flow method has received extensive attention for its specific characteristic in cell detection and other fields. In this work, we report on a study of sheath flow method in laser scattering particles size measurement. In the particles size measurement system, an optical fiber laser was used as laser source, the light sensitive was confined to circular region with a diameter of less than 10μm by micro-lens focusing structure. Based on the scattering theoretical analysis of the particle size distribution from the scattering light energy, an improved sheath flow structure is proposed to obtain accurate and reliable scattering light signal from the particle passing through sheath flow pool. The digital voltage signals were measured via the amplification circuit and the data acquisition card. Numerical calculations and experiment results show that the sheath flow system is effective in the laser scattering particles size measurement.

In this paper, we studied the structure characteristics of quantum dots-quantum well photodetector with response wavelength range from 400 nm to 1000 nm. It has the characteristics of high sensitivity, low dark current and the high conductance gain. According to the properties of the quantum dots-quantum well photodetectors, we designed a new type of capacitive transimpedence amplifier (CTIA) readout circuit structure with the advantages of adjustable gain, wide bandwidth and high driving ability. We have implemented the chip packaging between CTIA-CDS structure readout circuit and quantum dots detector and tested the readout response characteristics. According to the timing signals requirements of our readout circuit, we designed a real-time spectral data acquisition system based on FPGA and ARM. Parallel processing mode of programmable devices makes the system has high sensitivity and high transmission rate. In addition, we realized blind pixel compensation and smoothing filter algorithm processing to the real time spectrum data by using C++. Through the fluorescence spectrum measurement of carbon quantum dots and the signal acquisition system and computer software system to realize the collection of the spectrum signal processing and analysis, we verified the excellent characteristics of detector. It meets the design requirements of quantum dot spectrum acquisition system with the characteristics of short integration time, real-time and portability.

A novel design based on near forward light scattering detection system to measure size and concentration distribution of particles in liquids is reported. According to theory of Mie scattering, the influence of relative refractive index, particles size and wavelength on the detection results are discussed. A green optical fiber laser with 532nm was used as the excited light source. As a key part in the detection system, the focusing system using a lens structure to confine light sensitive area with Gauss distribution less than 80 μm². The lateral size of the sample cell is limited to 100μm. In order to measure the particles in non-overlapping state and improve the accuracy and repeatability, a novel structure in the sample cell was used and particle velocity through the sample cell was controlled by high precision stepper motor control system of micro circulation pump. Particle light scattering signal acquisition was completed by the poly lens combination system, according to the receiving angle relative to the measured particle, which can adjust the light scattering direction to obtain better particles light scattering signal. Photoelectric signal conversion, amplification and acquisition are all the devices with high precision. The measurement results showed that the measurement system was accurate and stable when the particles size in the range of 0.5-5μm.

In this paper we analyze the necessity of design of low temperature readout circuit. Since the photodetector should work in low temperature environment, it is necessary for the readout circuit with low temperature readout function. Meanwhile, the influence factors of ultra - low temperature on the CMOS readout circuit are analyzed. The main influencing factors are carrier freezing analysis, current mutation (Kink) and mobility change. Finally, we used JANIS SHI-4-2 liquid helium cycle refrigeration system as a refrigeration instrument, and do the test for the readout circuit at ultra -low-temperature. When the temperature of cold head of the cooling system reach to the minimum temperature (4.85K) and maintain 5 hours, Si substrate’ temperature reaches the minimum temperature (50.1K). By adjusting the static operating point voltage, we find that the circuit still works well.

In this paper, 64 pixels pulse frequency modulation (PFM) capacitive transimpedence amplifier (CTIA) readout integrated circuit (ROIC) for quantum effect photodetector is designed. The ROIC designed with 0.35 μm 2P4M technology achieves 1.24 Ge^- large charge handling with 50 fF small integration capacitor and 64 mW power consumption by pulse frequency modulation (PFM) technique. Compared to conventional integrated circuits, it has many advantages of anti-saturation, over 120 dB dynamic range (DR) realized by 10-bit counter, and can sense an input current range from few pA to few μA.

The design and analysis of achromatic double-prism scanners for free space laser communication is presented. Double prism canner consists of two independently rotating prisms; the two prisms are parallel and adjacent to each other. Compared with conventional two-axis optical electro-gimbals, the double –prism system has the advantages of high accuracy, compactness and good dynamic performance. But the wavelength of beacon and communication laser is different; the achromatic aberration caused by double prisms will result in alignment error between beacon link and communication link. Design results for the scanner, when used in 800nm and 1550nm demonstrated total fields of view 13 degrees with almost no aberration were presented. This will provide a new lightweight canner for free space laser communication.

When light travels in water, the state of polarization of the incident light changes as the photons are scattered with suspended particles or reflected on the target surface. In order to increase the working distance, underwater polarized light imaging (UPLI) technology usually makes use of the different depolarization effect between the water body and target on the incident polarized light to filter the backscattered light. So it is significant to study the depolarization characteristics of polarized light in water. In this paper, a Field Monte Carlo (EMC) program is developed to simulate the transmission characteristics of polarized light in water with specific particle and attenuation coefficient. EMC method is different from the traditional Monte Carlo method which tracks the Stokes vector of the beam. It uses the Jones mechanism to characterize the polarization state of the photons. By tracking the two vertical components of the photonic vibrating electric vector, the polarization state and the depolarization effect of polarized light transmitted through a body of water can be obtained. The simulation results are based on horizontal polarization, vertical polarization, 45 degree linearly polarized light(LPL) and right circularly polarized light(CPL) as incident light , Stokes vectors of four types of received light is obtained respectively, and the related parameters are calculated to analyze the polarization memory performance. The numerical results show that water body have good polarization memory property and the influence of the particle size and the attenuation coefficient on the LPL is obvious than that circularly of the polarized light, and the CPL has better polarization memory ability.

This paper uses semiconductor laser with 905nm wave length as light source to design a set of short-distance atmospheric laser communication system. This system consists of laser light source, launch modulation circuit, detector, receiving and amplifying circuit and so on. First, this paper analyzes the factors which lead to the decrease of luminous power of laser communication link under the applicable environment-specific sea level, then this paper elicits the relationship of luminous power of receiving optical systems and distance, slant angle and divergence angle which departures from the laser beam axis by using gaussian beam geometric attenuation mode. Based on the two reasons that PPM modulation theory limits the transmission rate of PPM modulation, that is, this paper makes an analysis on repetition frequency and pulse width of laser, makes theoretical calculation for typical parameters of semiconductor laser and gets the repetition frequency which is 10KHz, pulse width is50ns, the transmission rate is 71.66 Kb/s, at this time, modulation digit is 9; then this paper selects frame synchronization code of PPM modulation and provides implementation method for test; lastly, programs language based on Verilog, uses the FPGA development board to realize PPM modulation code and does simulation test and hardware test. This paper uses APD as the detector of receiving and amplifying circuit. Then this paper designs optical receiving circuit such as amplifying circuit, analog-digital conversion circuit based on the characteristics of receipt.

In distributed optical fiber sensing system of BOTDR, the frequency of the backward Brillouin scattering signal is modulated by temperature and strain, so the frequency of the signal can be attained with optical fiber to realize the temperature and strain measurement in remote. While, the scattering signal is very weak, the noise is large, and have a frequency width of several decades megahertz. In tradition, the complete high-frequency Brillouin scattering signal is obtained by adopting the method of frequency scanning which capture the frequency in section through changing the rate of sweep frequency module. And then, using multiple averaging measurement to reduce noise. But it is difficult to acquire the signal rapidly and eliminate the interference of noise. Therefore, an edge filter approach is proposed in this paper to get the whole scattering signal, which convert the frequency information into energy message. In order to better represent the effectiveness of this method, an experiment were taken. And the result shows that: SNR had been greatly enhanced, sampling time was reduced to the cost of getting one frequency point when using frequency scanning. It demonstrate that the proposed method can collect the signal quickly and be beneficial to demodulate temperature and pressure in time.

Advances in digital video compression and IP communication technologies raised new issues and challenges concerning the integrity and authenticity of surveillance videos. It is so important that the system should ensure that once recorded, the video cannot be altered; ensuring the audit trail is intact for evidential purposes. This paper gives an overview of passive techniques of Digital Video Forensics which are based on intrinsic fingerprints inherent in digital surveillance videos. In this paper, we performed a thorough research of literatures relevant to video manipulation detection methods which accomplish blind authentications without referring to any auxiliary information. We presents review of various existing methods in literature, and much more work is needed to be done in this field of video forensics based on video data analysis and observation of the surveillance systems.

Video surveillance systems play an important role in the crime scene investigation, and the digital surveillance system always requires the superimposed video data being subjected to a data compression processing. The purpose of this paper is to study the use of inpainting techniques to remove the characters and inpaint the target region. We give the efficient framework including getting Character Superimposition mask, superimposition movement and inpainting the blanks. The character region is located with the manual ROI selection and varying text extractor, such as the time. The superimposed characters usually have distinguished colors from the original background, so the edges are easily detected. We use the canny operator the get the edge image. The missing information which is effect the structure of the original image is reconstructed using a structure propagating algorithm. The experiment was done with C/C++ in the vs2010 KDE. The framework of this paper showed is powerful to recreate the character superimposition region and helpful to the crime scene investigation.

A two rings, triangular lattice photonic crystal fiber sensor element using surface plasma resonance phenomenon is proposed. The performance of the sensor is analyzed by finite element (FEM) analysis software Multiphysics COMSOL. The influence of structural parameters on the performance of the sensor is discussed. The results show that the maximum sensitivity is 6000nm/RIU, when refractive index is in the range of 1.31 to 1.38. The sensor can be directly placed in the liquid and platinum layer is placed outer surface of the photonic crystal fiber, which can simplify the manufacturing process and the measurement process , has important practical value.

With the VR(Virtual Reality) technology becoming a hot spot nowadays, one of the key technology--panoramic imaging technology is particularly important. This paper simply introduces various types of panoramic imaging technology, and compares the advantages and disadvantages of the hyperboloidal and paraboloidal catadioptric panoramic imaging system in principle and other aspects. The mathematical models of the hyperboloidal and paraboloidal system is established, and the related system is also designed.

A distributed optical fiber sensing system based on a bidirectional chaotic fiber ring laser has been proposed. The output waveforms induced by an external disturbance in some period are different from those in other time. This period equals the time difference between two counter-propagating beams arriving at the semiconductor optical amplifier (SOA) from the disturbance point. It is utilized for the disturbance location. In this paper, the location mechanism is explored by investigating optical interaction in the SOA in two simulation systems with a continuous wave optical source. One system is for studying the interaction of a continuous wave beam and a phase modulation beam input into the SOA from the left and right sides respectively. The other system is for investigating the interaction of two phase modulation beams counter-arriving at the SOA with a certain time difference. Under a small SOA current, only the transformation of the phase modulation to intensity modulation occurs due to the interference caused by facets reflection of the SOA. With the increase of current, the cross-gain modulation effect of the SOA makes the interference signal in one beam copy to the other one reversely in the phase, which generates the time difference characteristic. For the chaotic sensing system the situation is similar to the large current case in the second simulation system, only the conversion of the modulation format is achieved by the sensitivity to initial values of chaotic systems. The cross-gain modulation effect in the SOA contributes to the time difference location method.

The surface topography of micro-structures would significantly affect the products quality and industrial performance of micro-nano devices ^[1]. In recent years, the application of micro-structures in Micro Electro Mechanical Systems (MEMS) and integrated circuit is more and more widely. How to reflect the 3D surface topography of these micro structures accurately and measure the surface’s parameters precisely as well as quickly are becoming a hot research area of precision measurement. White-light interference microcopy technology is one of the most widely used non-contacting measurement methods at present, which has the advantages of nondestructive, fast measurement and high accuracy, has been widely applied in surface topography measurement of micro structures. In this paper, an analysis method of microstructure surface topography algorithm based on wavelet filter to analyze white interference signals is proposed, this method utilizes R/G/B three channels color information which is significantly superior to traditional black and white imaging process method. The experimental results shows that this method has good accuracy and repeatability in 3D surface measurement.

The structure of main lens - Micro Lens Array (MLA) - imaging sensor is usually adopted in optical system of light field camera, and the MLA is the most important part in the optical system, which has the function of collecting and recording the amplitude and phase information of the field light. In this paper, a novel optical system structure is proposed. The novel optical system is based on the 4f optical structure, and the micro-aperture array (MAA) is used to instead of the MLA for realizing the information acquisition of the 4D light field. We analyze the principle that the novel optical system could realize the information acquisition of the light field. At the same time, a simple MAA, line grating optical system, is designed by ZEMAX software in this paper. The novel optical system is simulated by a line grating optical system, and multiple images are obtained in the image plane. The imaging quality of the novel optical system is analyzed.

A coherence-free and reconfigurable filter based on semiconductor optical amplifier (SOA) is proposed and experimentally demonstrated. A high coherent RF-modulated light source is converted to an incoherent light source by employing the cross-gain modulation of amplified spontaneous emission (ASE) of the SOA. The inversely modulated ASE is sliced by an optical wavelength demultiplexer to realize a stable transversal microwave filter. Reconfigurability of the filter can be achieved by controlling the number and apodization of the taps. The filters with two, three and four taps are experimentally demonstrated.

To find a detecting method that can be applied to the clinical screening and diagnosis, the cascaded micro-ring sensor with Vernier effect was used to distinguish gastric cancerous and normal cells. The simulation by FDTD of the cascaded microring sensor with different refractive indexes of the analyte (normal cells and gastric cancer cells) will be presented. In the simulation, with the refractive index’s change Δn=0.02 for the two different analyte, the shift of sensor’s resonant wavelength is 6.71nm. And the cascaded micro-ring sensor’s sensitivity S is 335.5nm/RIU, and it is much larger compared to 19nm/RIU for a single ring sensor.

Coherent optical RF receivers constructed in self-homodyne configurations have gained considerable attention due to its simplicity and cost-efficiency. Rigorous symmetry is required in such system to suppress the laser phase noise. A method for evaluation of the un-eliminated laser phase noise in self-homodyne coherent optical RF receivers has been presented in this paper. In our proposed scheme, the un-eliminated laser phase noise is acquired by simply inserting an FBG in the in-phase arm and is found to be dependent on the interferometer asymmetry, i.e., the path imbalance of the interferometer arms. With series of simulations, the variance of the un-eliminated laser phase noise obtained by our method becomes larger when the path imbalance is increasing. The simulation results show that, variance increases with the asymmetrical time delays of two interferometer arms. Therefore, this method is very helpful in obtaining further insight into the system symmetry and is also a good guidance for the adjustment of the interferometer architecture to achieve the optimized path equality.

A pre-distortion algorithm of generating driving signals was proposed for high-order QAM modulation based on IQ modulator. IQ modulator working in the nonlinear area and driving by non-uniform signals was employed. The pre-distorted driving signal requires lower signal-to-noise ratio than the common uniform driving signal in QAM modulation.

Terahertz radiation was generated with several designs of photoconductive antennas (strip line, dipole, trapezoid, bow-tie) fabricated on low-temperature-grown GaAs (LT-GaAs) and the emission properties of the photoconductive antennas were compared with each other. The bow-tie photoconductive antennas with nano cylinder also be fabricated. The radiation characteristics of each antenna was characterized by THz-TDS. The radiation power of the photoconductive antennas with different antenna shapes showed significant difference. The underlying physics of nano-structured PCAs are still in their early stages. Our findings will pave the way for new perspectives in the design and analysis of novel structures for more efficient THz photonic devices.

A photonic microwave down-conversion approach is proposed and experimentally demonstrated based on a Mach-Zehnder modulator paralleled with a phase modulator. The incident radio frequency signal and the local oscillator signal are feed to the MZM and PM, respectively, and these two modulated optical signals interfere in the coupler. The useless higher-order sidebands are removed by a tunable optical band-pass filter. The principle of microwave frequency down-conversion is analyzed theoretically, the MZM and PM paralleled frequency down-conversion system is built. Then the performance of system is tested, and the experimental results show that the spurious-free dynamic range achieves 104.8 dB:Hz^2/3. Compared to the conventional MZM-MZM cascaded system, the SFDR has been improved by 16 dB. The MZM and PM paralleled frequency down-conversion system can balance the intensity of the two coherent beams easily, and only single DC bias is needed. The proposed method possesses simple structure and high dynamic range.

The leapfrog alternating direction implicit finite difference time domain (ADI-FDTD) method is applied to analyze the response characteristics of dielectric under electromagnetic pulse (EMP) with prefect matched layer (PML) boundary condition. It can deal with electrically large object with unconditionally stability and less computational expenditures as its advantage. The two-dimensional field of computational region under exaction source in time domain, which is based on the leapfrog ADI-FDTD method and PML boundary condition, is realized with Matlab.

For adapting to performance requirement of ultra wide-band and ultra high-speed signal processing in radar countermeasures equipment, a forwarding architecture of delay-superposition based on microwave photonics is suggested. Simultaneously, the method of delay-superposition modulation is researched and simulated. The interference effect is obtained briefly, which validated the effectiveness of microwave photonics delay-modulation in radar countermeasures.

In order to enriching the means of discriminating alfalfa and achieving the goal of nondestructive testing, terahertz time-domain spectroscopy (THz-TDS) was applied to explore and reveal the property characteristic of different alfalfa varieties in the same series. Six kinds of alfalfa were prepared for experiment and analysis, and these samples are classed as two series, namely caoyuan series and gannong series. In the result, the time-domain spectra were tested, and then the refractive indices and absorption coefficients was calculated, respectively. These spectrums showed an apparent difference between these two series, and to verify this classification, two statistical methods, partial least squares (PLS) and cluster analysis (CA), were performed to investigate. Finally, these methods yielded a classification result, and we found it classified gannong series and caoyuan series. All these result showed THz technology combined with statistical method can be an effective method for nondestructive identification of alfalfa breed with tiny different properties, and lay a foundation for establishing a forage database.

Beam steering characteristics of transmission liquid crystal optical phased array(LC-OPA) were measured using ultra precision electronic autocollimator. A continuous beam steering with a constant angular resolution in the order of 20 μrad is obtained experimentally from 0° to 6° based on the method of variable period grating (VPG).Meanwhile, the angular repeatability of less than 4 μrad (RMS) has been achieved.

In the near and middle infrared atmospheric window, infrared stealth material require a low absorptivity (which means a low emissivity according to Kirchhoff’s law of black body), at the same time, it also requires high absorptivity so as to decrease the reflectance at military laser wavelength of 1.06μm. Under this circumstances, compatible stealth of infrared and laser is an urgent demand, but the demand is ambivalent for conventional materials. Photonic crystal (PC), as a new type of artificial periodic structure function material, can realize broadband thermal infrared stealth based on its high-reflection photon forbidden band(also called photonic band gap). The high-reflection photon forbidden band of PC can be adjusted to near and middle infrared wave band through some rational methods. When a defect was added into the periodic structure of PC, a “hole-digging” reflection spectrum, which is high absorption at military laser wavelength of 1.06μm, can be achieved, so compatible stealth of near and middle infrared and military laser wavelength of 1.06μm can be achieved too.

In this paper, we selected near and middle infrared-transparent materials, Te and MgF₂ , as high refractive index and low refractive index material respectively, and designed a one-dimensional one-defect-mode PC whose photon forbidden band was broadened to 1-5μm by constructing two photonic crystals into one. The optical property of the PC was calculated by Transfer matrix method(TMM) of thin-film optical theory, and the results shows that the as-designed PC has a high spectral reflectance in the near and middle infrared band, among which the reflectivity in 1.68μm∼5.26μm band reached more than 90%, and the 2.48∼5.07μm band even reached 99.99%. The result also shows that between the band gap of 1-5μm, there are one defect mode locating in the wavelength of 1.06μm, whose reflectance is below 0.70%, which means its spectral absorptivity is greater than 99.30%. All the above we have discussed proved that this “hole-digging spectrum” PC can realize the compatible stealth of near and middle infrared and 1.06μm military laser.

A planar structure consisting of graphene layer as the hole transport material, and n-type silicon as substrate is simulated. The degradation of this cell caused by high interface state density has been carried out. The simulated results match published experimental results indicating the accuracy of the physics-based model. Using this model, the effect of interface state density as zero, 1×10¹⁶cm^-2, 1×10¹⁷cm^-2 on the photovoltaic performance has been studied. The obtained IV and EQE characteristic based on realistic parameters shows that the interface state playing a prominent role in graphene silicon schottky contact.

With continuous improvements of semiconductor laser performance and semiconductor laser technology, diode laser has been adopted in many applications in research and industrial areas, such as optical frequency standard, fiber communication, laser ranging, high resolution spectroscopy, laser cooling and trapping atoms, etc. Frequency stability and line width are the most important parameters concerned in special applications. In this paper, based on saturated absorption spectroscopy, we introduce the frequency stabilization of diode laser by metastable Kr atom. For its narrow natural line width, Kr transition can be used as a perfect frequency reference for laser frequency stabilization, and the reproducibility can also easily be achieved because of the intrinsic physical property. The laser frequency can also be shifted by an acoustic-optical modulator by precisely adjusting its driving frequency. This is important as one tries to manipulate different isotopes via the same laser. Methods of measuring frequency stability and line-width are also discussed at last.

In order to obtain the high-fidelity model of latching failure threshold power of the capacitive RF MEMS switch, it is necessary to find out the rough dielectric layer effect on its down-state capacitance degradation. The comparative modeling method between the 3-D electromagnetic simulation and the equivalent circuit simulation is proposed. First, the simulation curve of the switch isolation (S₂₁) is attained at different roughness levels with the HFSS 3-D electromagnetic model. And then the simulation curve of the S₂₁ of the ADS equivalent circuit model is consistent with the simulation result of the 3-D electromagnetic as far as possible by tuning the down-state capacitance in the equivalent circuit. Hence, the relationship between the dielectric layer roughness and the down-state capacitance is identified. By changing the roughness level of dielectric layer and repeating the above steps, the relationship between the dielectric layer roughness and the down-state capacitance degradation is identified. Rationality and feasibility of the method is verified by comparing the calculated values of the down-state capacitance with the measured values in a relevant literature. And analytical equation of the latching failure threshold power of the capacitive RF MEMS switch with perfect smooth dielectric layer is modified, according to the relationship between the dielectric layer roughness and the down-state capacitance degradation, which is also suitable for predicting the power handling capacity of the switch with rough dielectric layer.

True blue nitride laser diodes (LDs) are one of the key challenges for epitaxy of nitrides due to the variety of its potential applications. The growth of high temperature p-type layers may cause thermal degradation of the InGaN-based multiple quantum wells (MQWs) active region because of the annealing effect, since thick p-AlGaN layers were introduced as upper optical cladding layer in the LDs. The degradation was found in blue LDs grown on both Si and sapphire substrate. In the degraded LD wafer samples, “Dark” non-radiative MQWs regions were observed by microscopic photoluminescence. Formation of metallic indium precipitates and voids in these regions were confirmed by transmission electron microscope. The thermal degradation is attributed to the decomposition of indium-rich InGaN materials in the MQWs. The indium-rich InGaN materials were supposed to be accumulated at dislocation related V-shaped pits according to the surface morphology by atomic force microscope. To obtain high quality InGaN-based MQWs, one of the four methods can be introduced to eliminate the degradation. A lower thermal budget can suppress the decomposition of indium-rich InGaN clusters by a lower p-cladding layer growth temperature. The use of low threading dislocation density substrates results in low density indium-rich InGaN clusters. The introducing of H₂ carrier gas during the quantum barriers growth or a 2-step growth scheme with a higher quantum barrier growth temperature etches off the indium-rich InGaN clusters. The suppression of the thermal degradation in the MQWs makes it possible for lasing of blue laser diode directly grown on Si.

In this study, GaN-based flip-chip parallel micro light-emitting diode (μLED) arrays have been fabricated. Compared to a single LED with the same active region area, flip-chip parallel μLED arrays are superior on both modulation bandwidth and light output because of the uniform current spreading, improved heat dissipation, and higher light extraction efficiency. With this structure, an injected current density up to 7900 A/cm² has been achieved with a modulation bandwidth of ∼227 MHz. Meanwhile, the optical power is above 30 mW, which is more suitable for visible light communication in free space. The influence of resistance-capacitance (RC) time constant and carrier lifetime on the modulation bandwidth of parallel μLED arrays has also been investigated in details. This study will help the design of GaN-based LEDs to both enhance the modulation bandwidth and optical power.

We proposed a fully vertical-coupling and one-step etching subwavelength binary blazed grating (BBG) coupler with coupling efficiencies exceeding 80% at a wavelength of 1.55μm. Based on reflector grating and Bragg bottom reflector layer, the coupling efficiency gets its maximum 90% when λ is equal to 1.535μm with the 1 dB wavelength bandwidth is around 35nm. The BBG is formed with multiple rectangular pillars having different widths and uniform height, which is a kind of binary version of the triangular tooth shape of the blazed grating and can be easily fabricated by only one etching step. It is CMOS compatible and available for mass production.

We propose a Schottky photodetector with tapered thin metal strip on SOI platform. Schottky photodetector can detect photons below the semiconductor bandgap energy by exploiting the internal photoemission. In the internal photoemission process, the hot carriers generate in the tapered thin metal strip where light absorption occurs, and part of these carriers can be emitted over the Schottky barrier and collected as photocurrent. The small thickness of the tapered metal strip contributes to a high internal quantum efficiency of 11.25%. This metal-semiconductor structure acts as a photonics-plasmonics mode convertor. According to 3D-FDTD simulation, about 95.8% of the incident optical power can be absorbed in the absorption area within 4.5μm at wavelength of 1550 nm. The responsivity is estimated to be 0.135A/W at 1550 nm. This compact design with a low dark current has a minimum detectable power of -23.15 dβm. We argue that this design can promote the progress of all-Si photo-detection in near-infrared communication band.

Design a chip for flexible multifunction optical micro-manipulation based on elastomeric materials-PDMS. We realized the different motion types of microspheres, including stably capture, spiral motion and orbital rotation, by adjusting the input voltage of piezoceramics designed in PDMS Chip. Compared to conventional techniques, this PDMS chip based method does not require special optical properties of the microspheres to be manipulated. In addition, the technique was convenient and precise for dynamical adjustment of motion types without external influences. From these results, we verify that this multifunctional optical micro-manipulation technique of PDMS elastomeric materials can find potential applications for optical manipulation, including cost-effective on-chip diagnostics, optical sorting and optical binding, etc.

We report an integrated fiber-optic detector by dip coating PbS colloidal quantum dots onto a pretreated specialty fiber. We measured the readout current at 1550nm as a function of the optical power, the bias voltage and the distance between the contact electrodes.

Diffraction gratings are key components in many applications including pulse compression and stretch, optical imaging, spectral encoding and decoding and optical filtering. In this paper, spatial dispersion of two typical diffraction grating-based optical systems, single-grating system and grating-pair system, are thoroughly studied. The single-grating system consists of a diffraction grating to disperse the quasi-monochromatic lights and a convex lens to make the lights propagate in parallel and focused. In the grating–pair system, a pair of diffraction gratings is used to disperse the collimated lights in parallel. The spatial dispersion law for the two systems is developed and summarized. By investigating the spatial dispersion, the two systems are compared and discussed in detail.

A genetic algorithm is applied to optimize a taper between a large cross-section silicon-on-insulator (SOI) rib waveguide and a single-mode fiber to achieve an ultra-compact and highly efficient coupling structure. The coupling efficiency is taken as the objective function of the genetic algorithm in the taper optimization process. To apply the optimization algorithm, the taper is segmented into several sections. Three encoding forms and a two-step optimization strategy are adopted in the optimization process, resulting in a 10μm long taper with a coupling efficiency of 93.30% in quasi-TE mode at 1550nm. The characteristics of the optimized taper including the field profile, spectrum and fabrication tolerances in both horizontal and vertical directions are investigated via a three dimensional eigenmode expansion (EME) method, indicating that the optimized taper is compatible with the prevailing integrated circuit (IC) processing technology.

An approach to image the single virus by using Surface Plasmon Polariton Scattering was presented, which is potential for application in the fast, in-situ virus detection in water environment. Polarized by Surface Plasmon Polaritons, the nanoparaticle emits Surface Plasmon Polariton Scattering and interferes with the incident Surface Plasmon Polaritons, which is easy to be detected. The imaging to Surface Plasmon Polariton excitation was implemented. Meanwhile, the imaging to single 39 nm polystyrene nanoparticle and single T4 phage virus by using the Surface Plasmon Polariton Scattering was obtained. Both the imaging and the accurate counting of single virus can be obtained by using this method.

In the visible and near infrared regions, graphene is essentially transparent with a constant absorptivity of 2.3%. On contrast, in longer wavelengths, the absorptivity can be enhanced by graphene plasmons motivated by simple nanostructures. Besides, the graphene plasmons can be further enhanced via electrostatic doping when voltage is applied. This work numerically demonstrates that in optimized configuration the absorptance in monolayer graphene can be greatly enhanced and reach to 98.6% of the impinging light for transverse magnetic (TM) polarizations. Graphene can interact with light via plasmonic resonance. Towards this, we utilize a subwavelength-thick optic cavity, which composed of graphene grating, a dielectric spacing layer and a metal film to further enhance the interaction. When we use the TM mode source, the incident light matched the graphene plasmons, a strong drastic cut in the energy of the reflected light, which means obvious resonance absorption occurred. Meanwhile, the reflection can approach 0 when voltage applied. Finally, great absorption in 6.94 μm has been achieved by the graphene grating with the addition of a subwavelength-thick optic cavity via different voltage.

Based on digital signal processing theory, a novel and simple method is proposed to design asymmetrical film-microcavity interleaver filters (FMCIF) with arbitrary duty cycles. The transmission spectrums obtained have the characteristics of high isolation, great rectangular degree and wide flat passband. Design examples of different duty cycles are given and the influence of some key parameters on the spectral performance is discussed. The proposed method is simpler and more efficient than existing methods.

Guided-mode resonance filter (GMRF) with variable bandwidth using coupling gratings near the Brewster angle is presented. For the contact coupling gratings, the bandwidth of the GMRF can be significantly altered with the resonance location kept almost the same as the transverse shift is varied. The resonance location blue-shifts with the increase of the air gap thickness in both cases of S=0 and S=0.5. The filter bandwidth is increased exponentially with the increase of the air gap thickness at the aligned condition due to the decreased mode confinement. In the case of the maximum misaligned condition, the filter bandwidth is reduced exponentially with the increase of the air gap thickness due to the decreased mode coupling between the two misaligned gratings. The spectral response of the coupling gratings coincides with each other for both the aligned condition and the maximum misaligned condition when the thickness of the air gap is large enough. The resonance location almost does not move as it approaches the cutoff wavelength of the substrate. The sideband level is kept low as the transverse and horizontal shifts are varied due to the Brewster antireflection (AR) effect.

A five-channel silicon etched diffraction gratings (EDGs) working in the O-band was demonstrated in this paper. The device has a channel spacing of 20 nm and occupies a footprint of 180μm×120μm with an insertion loss of 5.3dB. Integrated heaters were designed to compensate the center wavelength shifts brought from fabrication errors. A tuning efficiency of 0.358nm/mA was obtained finally.

This paper presents a tunable optofluidic circular liquid fiber through the numerical simulation. Fiber is a significant optical device and has been widely applied on optical fiber communication. But the fiber based solid has limited tunability. Compared to solid fiber, the fiber based liquid material is relatively infrequent. Cause for the liquid optical device has more freedom tunable properties than solid counterpart, it has attracted more interest. The traditional optofluidic waveguide is designed like a sandwich in planar channel. This two-dimensional (2D) structure liquid waveguide will face huge transmission loss in the perpendicular direction of the flow streams. In this paper, a curving microchannel is designed inside the microchip to produce centrifugal effect. Two different liquids are injected into the chip by external pumps. In a particular situation, the core flow will be totally surrounded by the cladding flow. So the liquid can form an optical waveguide. Its structure is similar to an optical fiber which high refractive index (RI) liquid is core of the waveguide and the low RI liquid is cladding of the waveguide. Profit from the reconfigurability of liquid material, this liquid fiber has excellent tunability. The diameter of the core flow can be tuned in a wider range by changing the volume ratio of the flows through the finite element analysis. It is predictable that such a tunable liquid fiber may find wider applications in lab-on-a-chip systems and integrated optical devices.

Gold nanoparticles have very unique physical, chemical and biological characters, which makes them have widespread applications in many fields. Sorting gold nanoparticles with different size is of great importance because the unique properties of gold nanoparticles relate with their sizes extremely close. Optical sorting is an excellent way due to much better sorting precision compared with the traditional sorting methods. In this paper, a new chip design sorting gold nanoparticles is presented and results of sorting two different nanoparticles have been analyzed as well. Mie theory is used to calculate the optical force of nanoparticles in different diameter, and finite element analysis is used to analysis the variation of flow field and sorting process of gold nanoparticles.