Photoelectrical device and materials
2017, 46(2): 220001.
doi: 10.3788/IRLA201746.0220001
Photonic crystal fiber lasers have been paid much attention by many researches, and the preparation of photonic crystal fiber cores becomes the key problem in the study of the photonic crystal fibers. Er3+ doped aluminium-cadmium heavy-metal silicate glass sample was prepared by the method of high temperature melting. Its absorption and fluorescence spectra were measured. Using the Judd-Ofelt theory, its intensity parameter t (t=2,4,6), the oscillator strength and spontaneous radiation probability of the Er 3+ ion, fluorescence branching ratio, and the fluorescence lifetime were theoretically calculated. Using the fluorescence spectrum, the stimulated emission cross section of the 4I13/24I15/2 transition and the full width at half maximum(FWHM) of the fluorescence band were also measured. The result demonstrates that the Er3+ doped aluminium-cadmium heavy-metal silicate glass sample possesses a large stimulated emission cross section, a wide fluorescence FWHM, and high quantum efficiency of 92.6%. These parameters clearly indicate that this kind of silicate glass has a good laser excitation property and is expected to be applied in the study of the doped photonic crystal fibers.
2015, 44(2): 673-676.
Continuously tunable space optical attenuator has a wide prospect in various optoelectronic equipments. Based on the principle of Fabry-Perot interferometer, a new space optical attenuator was presented, its key component is a ZnSe crystal sheet, combined with a high accurate temperature control system, the attenuation ratio of laser beam can be tuned. The attenuation performance was measured with a Nd:YAG laser as light source. The experimental results indicate that the tuning range of the attenuator can reach 3 dB. Theoretical analysis shows that compared with thermal expansion coefficient, thermo-optic coefficient of ZnSe material plays a key role in determining the attenuator performance. In addition, by coating highly reflective dielectric film on both sides of ZnSe sheet, the tuning range can be further increased.
2015, 44(2): 677-681.
In order to realize long propagation distance and achieve subwavelength mode confinement, a dielectric-loaded hybrid surface plasmonics waveguide with a nano-hole was designed, which was based on traditional dielectric-loaded surface plasmonics waveguide.The propagation properties and mode field distributions of this novel hybrid waveguide were studied using finite-difference time-domain(FDTD) method. The results show that the structure could strongly modulate the local field enhancement. Furthermore, the nano-hole was filled with gain medium which leads to a gain enhancement, and the propagation loss could be compensated. In short, adjusting the geometrical parameters can significantly improve the confinement of the SPPs fields and reduce the losses of the waveguide. It also shows that the transmission loss is up to-13 dB/um in the case of d=44 nm. This surface plasmonics waveguide can be used for subwavelength optical confinement and applied to the field of photonic device integration and sensors.
2015, 44(2): 682-687.
The performance of optical components for fiber optic gyroscope (FOG) will degrade by ionizing damage effect and displacement damage effect in space radiation environment. Radiation effects on optical fiber, SLD optical source, and PIN-FET detector module were discussed respectively. In order to keep the performance of FOG in space, radiation protection technology was discussed from both radiation shielding and active hardening technology. Given that different optical components have different radiation sensitivity for different radiation damage mechanism, and there has a strict requirement on the weight of spacecraft payload, then the design of shielding was optimized on ionizing damage and displacement damage respectively. The active hardening technologies for every optical component were also discussed based on the analysis of radiation effects on each component.
2015, 44(2): 688-692.
Off-axis parabolic mirror has been widely used in sensor calibration, radiation measurement, infrared target simulation system and so on, because it takes many advantages such as no chromatic-aberration, common used material, broadband, no center block. The irradiance characteristic of the offaxis parabolic collimating mirror was evaluated by both theoretical analysis and simulation study. Both the expression for the irradiance distribution on the exit pupil plane of the off-axis parabolic collimator and the relations between the angle of divergence and the parameters of the collimator such as the focal length of the mirror, the aperture size of the source and the angle of off axis, were theoretically derived based on the radiation transfer model. The irradiance distribution on the exit pupil plane of the collimator was simulated by ray tracing method. The uniformity of the distribution was also analyzed. The method proposed here is useful to increase the collimation and uniformity of the off-axis parabolic mirror.
2015, 44(2): 693-698.
The application of UAV in the field of electro-optical reconnaissance is more and more widely. Desining a robust flight controller for UAV is an essential technique. A flight controller design method based on model matching and genetic algorithm optimization was proposed in this paper. A nonlinear model was used as the controlled object of this method. Compared with the classic flight controller design method, this method could access the needed controllers quickly and conveniently. A nonlinear mathematical six-degree-of-freedom model of a UAV was established, the aerodynamics, engine and environmental model were all included in this model. Using the above method, a UAV flight controller was designed. Based the finite state machine theory, the flight management model was established to design flight modes and carry out the controller switch. Finally, the six degrees of freedom nonlinear simulation was carried out to verify the effectiveness of the designed controller.
2015, 44(2): 699-704.
A newly modificated silicon (Si) avalanche photodetector (APD) desinged by standard complementary metal-oxide-semiconductor (CMOS) process was proposed in this paper. The basic structure of the Si APD which was formed by N-well/P-substrate was modificated with a deep N well below space charge area, and a independent voltage was applied on the deep N well to minish the transit time of electron hole pairs. The diffusion velocity and the drifting velocity can be improved at the same time, therefore, the 3-dB bandwidth will increase. The device parameters of CMOS APD were calculated with theoretical analysis, and the performance of the CMOS APD was optimized with SILVACO simulation, including technology simulation and device simulation. The simulation results show that when the window size of designed APD is 20 um 20 um and when biased at 16.3 V, the APD achieves avalanche gain of 20, the best responsivity of 0.47 A/W,the 3 dB bandwidth of 8.6 GHz.
2015, 44(11): 3181-3185.
An NIR band single-photon detector(SPD), based on GPQC with balanced APD-PIN junction capacitance and InGaAs/InP avalanche photodiode, was designed which was able to work in wide gating frequency range. The SPD was driven by a pulsed gate signal of any frequency below 200 MHz, which had amplitude of 10 Vpp and pulse duration of approximately 1 ns. A novel GPQC was devised based on high-frequency PIN diode that had similar capacitive characteristics compared with APDs, such that the low-frequency portion of capacitive response of the APD was suppressed. Subsequently, a group of 9th ordered Bessel LC low-pass filters(LPF) were used to suppress the residual high-frequency portion. At the temperature of -52 ℃ and gating frequency ranged from 0.1-200 MHz, the dark count probability and afterpulse probability at detection efficiency of 10% were below 610-6/gate, 1.9%, respectively, and the highest detection efficiency reached 26.4%.
2015, 44(10): 3005-3009.
In order to design one special filter with wide-refection, ZnS and Ag film was chosen as the layers based on the induced transmission filter. The ZnS layers were deposited by Ion Beam Assisted Deposition(IBAD) and treated using ion source deposition, and the Ag layer was deposited by magnetron sputtering. The rate of Ag film with different working parameter was discussed in this paper. At last, the best working parameters were chosen and deposited the induced transmission filter. The results indicate that it has over 90 percents of transmission from 750 nm to 850 nm and more than 90 percents of reflection from 2 500 nm, and the face-resistence is less than 300 . The filter has a good reflection infrared and anlistatig character.
2014, 43(S1): 157-163.
In order to meet the needs of low-cost, high integration space instruments for space power systems, a space-based instrument C8051F040 chip power controller was designed. The major difference between the controller and the traditional design approach is the use of highly integrated lithium-ion battery controller chip (bq77PL900) as an integrated controller chip instead of analog circuits. By employing the bq77PL900, the size of power controller is reduced and the energy of the power controller used is decreased, and the anti-jamming ability of the system is enhanced. To improve the reliability of the system, the system uses the online EEPROM re-injection technology, which can be used to discover the knocked data. This experiment proves that this design not only greatly simple and reliable, but also enhance the efficiency of the system by 5%. This design can wildly used in low-cost space instruments and small satellites.
2014, 43(S1): 164-168.
SRAM-based FPGA in the space radiation environment is effected by single event, which leads to the occurrence of FPGA memory cell bit flip. When the flip up to a certain extent, the function may become errors. To assess the sensitivity of FPGA single event and improve the reliability of FPGA single event, the key technology to realize fault injection was studied, the existing technology was analyzed, SEU sensitive bit test system was designed, based on partial reconfiguration feature of SRAM-based FPGA, and the modified FPGA configuration data bits was used to simulate a fault zone, the method accelerated the process of system failure, realized the single event upset sensitive position detection and statistics. Experiments show that the design is reasonable, implementation is flexibale, and cost is low, and provides favorable support for SRAM-based FPGA anti-tolerant design.
2014, 43(S1): 169-176.
One of the major problems that restricts the widely use of hard and brittle materials is the quality and efficiency of fabrication. To deal with this,improving fabricaiton efficiency and quality of hard and brittle materials needs to be quickly solved. To a large extent, high efficiency could imply the quality may get worse. Keeping up high efficiency and good quality seems to be contradictory in the meantime. Since the grinding thermal situation was one of the key elements that could affect the fabrication quality, this article aims to analyze the thermal situation in the process of fabrication of carbon dioxide and aluminum oxide by studying the relationships between grinding temperature and grinding parameters which include grinding wheel linear velocity, grinding depth and workpiece speed. In the meanwhile, it compared the thermal results between carbon dioxide and aluminum oxide in purpose of providing useful information and reference for fabrication.
2014, 43(S1): 177-182.
A high-accuracy temperature control system for light filter of auroral imager was proposed in the paper. Platinum resistance was used as the temperature sensor, and the temperature measuring circuit can collect the temperature with an accuracy of 0.05 ℃. A DSP was used as the main control unit, which implemented a full digital control system. The heater plate used constant current source circuit as its driving circuit, implementing the high precision and low noise heating power control. The mathematical model of the system was established, and the key parameters were identified from step response curves of the practical light filter system. The controller was designed based on the identified model and simulation results show the performance of the designed controller. Then, the parameters of the controller were tuned in experiments and experiment results show that better performance is obtained using optimized controller. At last, experiments results were discussed and show that high accuracy temperature control of the light filter system was implemented.
2014, 43(S1): 183-187.
The stability of space remote pointing mirror plays a vital role in improving image geometric accuracy, and it is determined by adhesives. First of all, the requirement of remote sensor to pointing mirror's stability was analyzed in this paper. Then the three commonly used for aerospace adhesive were compared comprehensively. Combining with the actual requirements of pointing mirror, HY914 and SE-14-80 adhesives were chose to compare the stress of glue bonding. By setting a reasonable curing process for both adhesives, and under the same conditions, the pointing stability was examined before and after the test verification. Experimental results show that with the specific curing process,the pointing error of pointing mirror using SE-14-80 adhesive was 1 before and after bonding, and SE-14-80 is more suitable for use in bonding in space optical remote sensor pointing mirror. Given its excellent adhesion, this adhesive is applied in a research project.
2014, 43(S1): 188-192.
The gel-casting of reaction bonded silicon carbide, which is a material of space mirror, was processed by organic precursor impregnation. A silicon carbide ceramic component with fine secondary -SiC distributed uniformly in the matrix was prepared. The density and the microstructure in the impregnation process were investigated. The density of the sample without impregnation process was 2.945 g/cm3 after reaction sintered. Density increased to 2.969 g/cm3 after one time impregnation, and increased to 3.011 g/cm3 after two times impregnation. The proportion of fine SiC in microstructure went up with the increasing of the impregnation times. In which the reaction sintered process, the carbon introduced by impregnation and silicon reacted to form fine -SiC dispersed in matrix. Bending test was conducted for the samples. The bending strength of the sample without impregnation process was 308 Mpa. Bending strength increased to 339 Mpa after one time impregnation, strength increased by 10.1%, and increased to 380 MPa after two times impregnation, strength increased by 23.4%, which improve the mechanical properties greatly.
2014, 43(S1): 193-196.
The join slurry is composed by silicon carbide(SiC) powder, phenolic resin and carbon black. Joining SiC green body after deairing, and then the reaction bonded SiC(RBSiC) joining mirror blank was prepared by reaction sintering. The relationship of the slurry formula and the microstructure of weld were discussed. The bending strength and the coefficient of thermal expansion of joining RBSiC ceramic were tested. The research shows that PEG200 and PVP can make carbon black dispersing homogeneous in the join slurry, and there is no residual carbon black in the weld after reaction sintering, so the microstructure of RBSiC ceramic is no different from the weld. The blending strength of joining green body and joining RBSiC ceramic are 24.9 MPa and 322.9 MP arespectively, and the fracture occurred in the base material. The CTE of base and weld material is only 0.011 4 ppm during -100-400 ℃.
2014, 43(S1): 197-202.
The effects of nano-SiC power additive on rheological behavior of SiC slurry and mechanical properties of RBSC were investigated. SiC blanks were prepared with gel-casting method, through drying, burning out the organic elements, infiltrating silicon and reaction sintering, the RBSC with nano-SiC particles were fabricated. Influence of solid loading, ball-milling time and nano-SiC particles on rheological behavior of SiC slurry was discussed. Due to the addition of nano-SiC particles, SiC slurry rheological behavior was changed from shear thinning to first shear thickening, then shear thinning. With 7% nano-SiC powder, the bending strength and elastic modulus of RBSC were elevated to 345 MPa and 339 GPa,respectively increasing by 18.1% and 13.8%. RBSC mechanical properties were improved with the addition of nano-SiC powder.
2014, 43(6): 1812-1817.
The traditional methods for spacecraft autonomous navigation need several sensors, such as star sensor, infrared horizon sensor and magnetometer, to collect navigation data. As a result the load of spacecraft will gain in weight, size and power. Based on the advantages of multi-field of view (FOV) star tracker, an autonomous navigation method was proposed which used multi-FOV star tracker (MFST) to image the star and the earth respectively and got the orientation vectors of them. Combining with the orbit parameters of the spacecraft and the layout of the MFST, a mathematic model of the earth imaging was set up to implement the earth edge images in every single FOV. The Steger method was used to determine the earth edge in the images. Considering the earth oblateness, the orientation vector of the earth will be obtained through circle-fitting the earth edge points in each FOV. With the configuration that one FOV measures the navigation star and the other two FOV measures the earth edge, the autonomous orientation based on the starlight angle is simulated and the result indicates that the accuracy of the earth vector and the spacecraft position respectively reaches 0.017 2(1) and 190 m(1)。
2014, 43(6): 1818-1822.
The classifier plays an important role for cloud detection in remote sensing image. Traditional Classifiers demand excessive training samples and have risks to fall into local optimum. To solve these deficiencies, SVM was presented as the classifier to achieve cloud detection based on SVD as feature vectors. Meanwhile, the method of minimizing the support vector count was introduced to substitute cross-validation method for optimal parameters selection. Experiment over high resolution remote sensing images QuickBird showed, with this method, the correction rate of cloud detection could be higher than 99%. It also suggested support vector count could reflect the classifier's estimation accuracy and was more easy to compute. The SVM classifier established in this way, compared with BP neural network, needed fewer training samples but achieved higher accuracy, it showed better performance in cloud detection field.
2014, 43(6): 1823-1829.
The 45-degree-rotated scanning mirror (RS mirror) was employed into the field of Wide-of-View (FOV) imaging with a scanning TDICCD camera by using the Coordinate Transformation method of building sub-satellite point image motion model with the Satellite Borne TDICCD camera. The imaging characteristics of the RS mirror and the Offsetting Image Rotation principle of the K Mirror were fully discussed. The effect diagram after offsetting image rotation with the K Mirror was further simulated to verify the rationality of K Mirror. Based on the light vector transformation matrix of the RS Mirror and K Mirror, the image rotation model was finally derived when bearing scanning TDICCD camera was used, which could support the theoretical foundation of subsequent image rotation analysis.
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