Journals >Acta Photonica Sinica
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2011
Volume: 40 Issue 5
30 Article(s)
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Research Article
Control of Radiation Characteristics of a Micro Random-laser
WANG Hui-qin, LIU Zheng-dong, and YU Ao-lie
To control the radiation characteristics of random laser effectively, the random medium nano-cluster was put in a photonic crystal(PC). The finite difference time domain(FDTD) method was used to simulate its radiation characteristics after it was placed in the air and in the PC. The results show that if the cluster is To control the radiation characteristics of random laser effectively, the random medium nano-cluster was put in a photonic crystal(PC). The finite difference time domain(FDTD) method was used to simulate its radiation characteristics after it was placed in the air and in the PC. The results show that if the cluster is put in the air, the radiation energy decreases gradually after being excited, and its emission spectra take on spontaneous emission characteristics. However, when the cluster is introduced into a PC, some spontaneous emission spectral peaks will drop off, one of which will leave and grow in intensity rapidly. Finally, it becomes the strongest single spectral peak. Therefore, if a random gain system is able to be put into a matching ordered system, the light can be confined and the spontaneous emission can be forbidden..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 647 (2011)
Influence of Nonmagnetic Microsphere Doping on Magnetic-field-induced Birefringence of Nanostructured Magnetic Fluids
SUN Guo-qing, PU Sheng-li, LIU Ming, and DAI Min
Composite magnetic fluids were obtained by doping silicon dioxide and polystyrene nonmagnetic microspheres into the pure ferrite magnetic fluids. The relationship between the magnetic-field-induced birefringence of composite magnetic fluids and the species, concentrations of nonmagnetic microspheres and pure ferrite maComposite magnetic fluids were obtained by doping silicon dioxide and polystyrene nonmagnetic microspheres into the pure ferrite magnetic fluids. The relationship between the magnetic-field-induced birefringence of composite magnetic fluids and the species, concentrations of nonmagnetic microspheres and pure ferrite magnetic fluids were investigated qualitatively. The results indicate that pure magnetic fluids with different concentrations doped with equal quantity of polystyrene microspheres have different variation trends for the birefringence with respect to the externally magnetic field. Different kinds of nonmagnetic microspheres have different influences on the change of birefringence after doping into the same pure magnetic fluids. When doping with two-kind-mixed nonmagnetic microspheres (equal quantity but different proportion between the two kinds of microspheres), one kind of the nonmagnetic microspheres will play a leading role in the variation of birefringence with externally magnetic field. Then, the variation trend of the birefringence with externally magnetic field for the as-prepared composite magnetic fluids is similar to that only doped with the leading nonmagnetic microspheres..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 652 (2011)
Synthesis and Luminescence Properties of La2(WO4)3∶Eu3+ red Phosphors as LED Application
LIAO Jin-sheng, YOU Hang-ying, WEN He-rui, CHEN Jing-lin, YOU Wei-xiong, and WEI Yin-wei
Eu3+-doped La2(WO4)3 phosphors were synthesized by a hydrothermal method with further heat treatment. X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) were used to characterize the resulting samples of crystal phase structure, particle size and morpholEu3+-doped La2(WO4)3 phosphors were synthesized by a hydrothermal method with further heat treatment. X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) were used to characterize the resulting samples of crystal phase structure, particle size and morphology and composition. Photoluminescence excitation and emission spectra and decay curve were used to characterize the fluorescence properties of phosphors. XRD analysis confirmed that the precursors and as-prepared sample (900 ℃ for 2 h) were α-La2W2O9 with triclinic structure and La2(WO4)3 with monoclinic structure, respectively. The results show that La2(WO4)3∶Eu phosphor exhibits intensive red emission under 395 nm excitation. The strongest line (395 nm) in excitation spectra of these phosphors matches with the output wavelength of UV InGaN-based light-emitting diodes (LEDs) chip. Hence, it is considered to be a new promising phosphor for generating white light devices..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 658 (2011)
Optimization Design on Packaging Materials of High-power LED for Lighting
LIU Yi-bing, DAI Yu-xing, and HUANG Zhi-gang
According to heat transfer theory, a finite element model of high-power light emitting diode(LED) was established. Four kinds of bonding materials(silver conductive adhesive with high thermal conductivity, nano-silver paste, power chip bonding adhesive, Sn70Pb30), and four kinds of substrate material(Al2O3, AlN, Al-SiCAccording to heat transfer theory, a finite element model of high-power light emitting diode(LED) was established. Four kinds of bonding materials(silver conductive adhesive with high thermal conductivity, nano-silver paste, power chip bonding adhesive, Sn70Pb30), and four kinds of substrate material(Al2O3, AlN, Al-SiC, copper-molybdenum alloy)were chosen. ANSYS finite element thermal analysis software was used to simulate temperature field, and the optimal choice of materials for high-power LED package was obtained. The influences of the substrate thickness, chip output power and external heat sink on the LED junction temperature were studied. The results show that the nanometer silver soldering paste-AlN has the most superior radiation effect the increase of the substrate thickness will not increase the head dissipation capability obviously; because the signal LED output power is limited, the packaging structure should be optimized and the multi-chip array needs to be used to the illumination requirement; the external aluminum heat-sinking is able to achieve the ideal heat-sinking effect..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 663 (2011)
Design and Optimization in Constructing An In-vivo Confocal Laser Scanning Microscopy
LI Zhao-hui
Confocal laser scanning microscopy(CLSM) is an invaluable tool for a wide range of investigations in the biological and medical sciences. A type construction of laser con-focal scanning and fluorescent detection system was provided. A polygon mirror and a galvanometer scanner were used to implement x-y scan. The relay Confocal laser scanning microscopy(CLSM) is an invaluable tool for a wide range of investigations in the biological and medical sciences. A type construction of laser con-focal scanning and fluorescent detection system was provided. A polygon mirror and a galvanometer scanner were used to implement x-y scan. The relay optical system was designed based on commercial lens with optimized consideration to achieve small scan spot size, large Field-of-View and high efficiency. Fluorescence was detected by a photomultiplier tube with excellent signal-to-noise ratio. The scan system control and image acquisition were designed with an optimized scan velocity and sample clock. All these measures could reduce the blurring effect in the whole imaging process and improve the resolution. The analysis results show that the design of the CLSM is reasonable and all components achieve an optimized consideration for in-vivo scanning imaging; this type of CLSM are easily accessible and can be upgraded according to optical requirements; the performance is comparable to available commercial products, but is superior in many aspects of cost, flexibility and versatility..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 667 (2011)
Optical Design of Spaceborne Shortwave Infrared Imaging Spectrometer with Wide Field of View
XUE Qing-sheng, LIN Guang-yu, and SONG Ke-fei
Based on the requirements of shotwave infrared imaging spectrometer with wide field of view, considering the restrictive off-the-shelf detectors, a split field of view (FOV) method was developed. The principle of split field of view was analyzed. A spaceborne shortwave infrared imaging spectrometer with wide field of vBased on the requirements of shotwave infrared imaging spectrometer with wide field of view, considering the restrictive off-the-shelf detectors, a split field of view (FOV) method was developed. The principle of split field of view was analyzed. A spaceborne shortwave infrared imaging spectrometer with wide field of view was designed using the method. The imaging spectrometer are composed of a 11.42° telecentric off-axis three-mirror anastigmatic telescope and two offner convex grating spectral imaging system. Ray tracing, optimization and analyzing were performed by CODE V and ZEMAX software. The analyzed results demonstrate that the modulation transfer function for different spectral band is more than 0.7 which satisfies the pre-designed requirement..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 673 (2011)
Dynamic MTF Analysis and Research for Aerial Camera
LIAO Jing-yu, GAO Xiao-dong, and LIANG Wei
Using Modulation Transfer Function(MTF) method to evaluate image quality and establish reasonable stabilization system performance standard, is a serious problem during the design process. Based on transfer function theory of linear optical system, dynamic image process during uniform, accelerated and sinusoidal motionUsing Modulation Transfer Function(MTF) method to evaluate image quality and establish reasonable stabilization system performance standard, is a serious problem during the design process. Based on transfer function theory of linear optical system, dynamic image process during uniform, accelerated and sinusoidal motions were studied and numerically analyzed. The relationship between image motion and dynamic image quality was established. And a new method based on discrete phase intervals was especially developed to evaluate low frequency sinusoid motion. The analysis and results indicate that with the same image blur of 0.5 pixel, MTFs of high frequency sinusoid motion, linear motion and low frequency motion can respectively reach 0.85, 0.9 and 0.998, to obtain good dynamic images. The conclusion was made that high frequency vibration damages the image quality most, linear motion less and low frequency does the least. According to analysis given, dynamic MTF can be solved for a certain image motion, to offer quantitative reference for the image evaluation of aerial camera..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 679 (2011)
Dynamic Bandwidth Allocation Algorithm for Orthogonal Frequency Division Multiplexing Access-passive Optical Network
CHEN Cun-kang, QIAO Yao-jun, and JI Yue-feng
An architecture of next generation access network namely orthogonal frequency division multiplexing passive optical network was presented, which has high spectrum efficiency, fine bandwidth granularity and low cost. A novel efficient dynamic bandwidth allocation algorithm based on orthogonal frequency division multipleAn architecture of next generation access network namely orthogonal frequency division multiplexing passive optical network was presented, which has high spectrum efficiency, fine bandwidth granularity and low cost. A novel efficient dynamic bandwidth allocation algorithm based on orthogonal frequency division multiplexing passive optical network namely fixed cyclic polling in pipeline dynamic bandwidth allocation algorithm was investigated. To meet the quality of service requirements under multi-services access scenario, two level bandwidth allocation mechanisms, bandwidth pre-request for expedited forward service and the smallest bandwidth request allocated the first principle for assured forwarding and the best effort services were applied in this algorithm. A simulation was conducted to study the performance of fixed cyclic polling in pipeline dynamic bandwidth allocation algorithm in orthogonal frequency division multiplexing passive optical network. The results show that the proposed algorithm supports expedited forwarding services with low packet average delay and low jitter, balances priority and fairness between assured forwarding services and best effort services, and achieves bandwidth allocation fairness among different optical network units in the same priority. Compared with the traditional dynamic bandwidth allocation algorithms, fixed cyclic polling in pipeline algorithm meets the quality of service requirements excellently, and adapts orthogonal frequency division multiplexing passive optical network better with higher bandwidth efficiency and lower algorithm complexity..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 686 (2011)
A Fiber Bragg Grating Sensor of Steel Corrosion at Different Humidities
CAI Han-li, HU Wen-bin, ZHANG Yan-xiao, DING Li-yun, and CHEN Wei
A prototype Fiber Bragg Gratings (FBG) sensor for monitoring corrosion of steel structures was presented and the performances were characterized at different humidities. The sensor was fabricated by sputtering and electroplating a sensitive metal film on FBG side-face. The surface micro-structures of sensor at differenA prototype Fiber Bragg Gratings (FBG) sensor for monitoring corrosion of steel structures was presented and the performances were characterized at different humidities. The sensor was fabricated by sputtering and electroplating a sensitive metal film on FBG side-face. The surface micro-structures of sensor at different humidities were investigated by Scanning Electron Microscope during a 27-day experimental cycle. The shifting of wavelength was recorded by Optical Spectrometer Analyzer in two environments with humidity of 60% and 99% RH. The wavelength of FBG sensor at 60%RH increased linearly with an increment of 0.025 nm per day. For sensors at 99%RH, the chirping appears, which implies more serious corrosion occurs than that at 60% RH. The experimental results show that the proposed FBG corrosion sensor is applicable for corrosion monitoring at a humidity of lower than 60%RH, and applicable for early alert of corrosion at a higher humidity..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 690 (2011)
Experimental Investigation on Near Gaussian-shaped Spectrum Erbium-Doped Fiber Super-flourescent Source in Double-pass Forward Configuration
YE Wei-wei, FANG Hong, LIU Cheng-xiang, WU Xu, RUAN Shuang-chen, and ZHANG Li
The on near Gaussian-shaped spectrum Erbium-doped fiber super-flourescent source was studied. The self-coherence function of Gaussian-shaped spectrum and the change of mean wavelength under different temperatures were theoretically analyzed. Using the double-pass forward configuration, the Gaussian-shaped spectrum was The on near Gaussian-shaped spectrum Erbium-doped fiber super-flourescent source was studied. The self-coherence function of Gaussian-shaped spectrum and the change of mean wavelength under different temperatures were theoretically analyzed. Using the double-pass forward configuration, the Gaussian-shaped spectrum was obtained with certain Erbium-doped fiber length. Meanwhile, pump powers could be adjusted to optimize the intrinsic thermal coefficient of Erbium-doped fiber. Finally, under the condition with erbium-doped fiber length of 10.05 m, LD power of 172 mW, the whole optical path (except pumping LD and the driving) in the environmental temperature from －40 ℃ to 60 ℃, the near Gaussian-shaped spectrum Erbium-doped fiber source with 66.651 ppm mean wavelength stability was obtained..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 694 (2011)
Simulation the ASE Dynamics in the Pulsed-pumped Ytterbium-doped Fiber Amplifiers
ZHANG Wei-yi, NING Ji-ping, CHEN Bo, BAI Xiao-lei, HAN Qun, and ZHOU Lei
Implementation of pulsed-pump technique to fiber amplifier is significantly useful in the situation of low repetition rate and high energy pulses operating. The Amplified Spontaneous Emision (ASE) dynamics simulation in a pulsed-pumped ytterbium-doped double-clad fiber amplifier was presented, which provides important Implementation of pulsed-pump technique to fiber amplifier is significantly useful in the situation of low repetition rate and high energy pulses operating. The Amplified Spontaneous Emision (ASE) dynamics simulation in a pulsed-pumped ytterbium-doped double-clad fiber amplifier was presented, which provides important references about optimizing the pulsed-pump mode. By solving the rate equations and light power propagation equations in fiber using the finite elements analysis method, the simulations of ASE dynamics were carried out, including evolution of forward, backward ASE power distribution in the fiber and variations of ASE output power at two ends of the fiber in the time span from 0~740 μs after injection of pump light. Through the analysis of simulation results, the difference between forward and backward ASE powers increasing speeds and characteristics of the two kinds of ASE powers distributions dynamic in fiber were indicated..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 699 (2011)
Diffuse Optical Tomography of Small-Animal-Sized Tissues Based on the Steady Radiative Transfer Equation
JIN Meng, GAO Feng, YANG Fang, LI Jiao, and MA Wen-juan
Based on the radiative transfer equation and the algebraic reconstruction technique, an advanced algorithm of diffusion optical tomography was developed within the framework of Newton-Raphson’s inversion. The standard algebraic reconstruction technique was improved to achieve simultaneous reconstruction of both the absBased on the radiative transfer equation and the algebraic reconstruction technique, an advanced algorithm of diffusion optical tomography was developed within the framework of Newton-Raphson’s inversion. The standard algebraic reconstruction technique was improved to achieve simultaneous reconstruction of both the absorption and the scattering images for small-animal-sized geometry. The numerical simulations validated the feasibility of the proposed scheme and demonstrated the superiority of the modified algebraic reconstruction technique over the standard one in separation of both the coefficients..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 705 (2011)
Ramage Repair for Enhanced Ultraviolet-B Radiation on Antioxidant System of Arabiodopsis by He-Ne Laser
JIANG Xiao-yan, GAO Li-mei, LI Yong-feng, and HAN Rong
Taking Arabidopsis trained about six weeks as the material,UV-B radiation(1 kJ/m2/d) and He-Ne laser irradiation(wavelength 632.8 nm output power 5 mW·mm2, irradiation time 60 s) were used to process the material.The Arabidopsis were divided into four treatment groups including CK(not treated ),L(He-Ne laser) ,B(UTaking Arabidopsis trained about six weeks as the material,UV-B radiation(1 kJ/m2/d) and He-Ne laser irradiation(wavelength 632.8 nm output power 5 mW·mm2, irradiation time 60 s) were used to process the material.The Arabidopsis were divided into four treatment groups including CK(not treated ),L(He-Ne laser) ,B(UV-B), and BL(UV-B +He-Ne laser).The experimental results show that enhanced UV-B increases the contents of MDA,O.－2and the activities of PAL, CAT,APX ,while SOD activity and the content of GSH decrease. But He-Ne laser irradiation reduces the contents of MDA and O.－2,the PAL activity, and increases SOD activity, APX activity, CAT activity, the content of GSH .In contrast to B group, both enhanced UV-B and He-Ne laser have similar results which indicated by He-Ne laser irradiation. The results prove that laser can improve the ability of antioxidant system in Arabidopsis..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 712 (2011)
Biological Tissue′s Temperature Field During the Laser-Induced Interstitial Thermotherapy
BAO Mei-fang, QIAN Zhi-yu, LI Wei-Tao, XIAO Di, WANG Jin-yang, and QIAN Lu
The temperature distribution of the accurate biological tissues in different powers and different irradiation times is the premise of efficacy of laser-induced interstitial thermotherapy assessment. A three-dimensional finite element heat transfer model was constructed by multi-physical field conductive coupling analysThe temperature distribution of the accurate biological tissues in different powers and different irradiation times is the premise of efficacy of laser-induced interstitial thermotherapy assessment. A three-dimensional finite element heat transfer model was constructed by multi-physical field conductive coupling analysis software COMSOL Multiphysics in the invariable tissue optics parameters situation. The model was based on Pennes bio-heat transfer equation and axisymmetric Gaussian shape of the laser beam heat equation. In this model, the parameters were for the liver tissue in vitro, and the thermal properties of biological tissue density, specific heat and thermal conductivity with temperature variations were considered. The temperature field data sets were obtained by simulation under the laser power for 0.77 W, 0.95 W, 123 W, irradiation time for 10~90 s, radial distance range 0~2 mm and axial distance range 0~4 mm. Fitting algorithm was used to obtain the tissue′s temperature distribution model related to the laser power, irradiation time, radial and axial distance. The results of 0.88 W and 1.05 W were compared with the Pennes equation, and the error between them was within 5%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 718 (2011)
Sorting Economic Microorganisms by Using Optical Manipulation and Raman Microspectroscopy
LI Zi-da, TAO Zhan-hua, MENG Ling-jing, CHEN Shan-shan, LIU Jun-xian, and WANG Gui-wen
A novel techique of sorting yeast cell based on Raman characteritics of target products synthesized by microorganisms was developed by using Raman microspectroscopy coupled with optical manipulatation. To sort oleaginous yeast and carotenoid-producing yeast, the plant oil and β-carotene were chosen as the target producA novel techique of sorting yeast cell based on Raman characteritics of target products synthesized by microorganisms was developed by using Raman microspectroscopy coupled with optical manipulatation. To sort oleaginous yeast and carotenoid-producing yeast, the plant oil and β-carotene were chosen as the target products and their Raman characteritics, the intensity ratios of 1 440 cm－1 and 1 602 cm－1 band (i.e. I1440/I1602) for oil, and I1157/I1654 or I1520/I1654 for carotenoid, were extracted and marked as target cells. Single yeast cell was captured and manipulated by using a 780 nm laser, and the Raman spectra of trapping cell was acquired simultaneously.A real-time computer distinguishing program was used to assist the sorting. The distinguished cells were then extracted and validated by following culture and Raman detection. This work provides a new method for screening microorganisms synthesize products with economic value..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 722 (2011)
The Effects of Radial and Positional Disorders on Two-dimensional Photonic Crystal Waveguides with Different Air-holes
ZHANG Xuan, TIAN Hui-ping, and JI Yue-feng
The impact of positional and radial disorders on the transmission spectrum of photonic crystal waveguides with different shapes of air-holes, including circular, square and elliptic were numerically investigated. It was found that the disorder affects the anti-crossing point greatest. The flat transmission spectrum becThe impact of positional and radial disorders on the transmission spectrum of photonic crystal waveguides with different shapes of air-holes, including circular, square and elliptic were numerically investigated. It was found that the disorder affects the anti-crossing point greatest. The flat transmission spectrum becomes narrower as disorder increasing. The transmission property performs more sensitive on the air-holes positions than radii. The square air-holes are more robust against the positional disorder. The circular air-holes are more robust alainst the radial disorder. These results provide important theoretical instructions on the imperfection during the manufacture possess in the PCWs experiment..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 728 (2011)
Development of Photonic Crystals Using Water-resisting Photopolymer
HAN Jing, ZHANG He-ling, and ZHAO Tian-qi
A novel recording material of holographic fabrication for photonic crystal was proposed. The material is home-made water-resisting photopolymer. Using green laser as the laser source, its performance parameters were simply measured. After testing, its diffraction efficiencies could reach 85%, and its absolution is highA novel recording material of holographic fabrication for photonic crystal was proposed. The material is home-made water-resisting photopolymer. Using green laser as the laser source, its performance parameters were simply measured. After testing, its diffraction efficiencies could reach 85%, and its absolution is high with the wavelength of 514.5 nm. Besides, the later development is simple, only heating. Holographic fabrication of photonic crystal was also simply simulated by Matlab software. The results indicate that the more beams interfere, the more complex photonic structures of photonic crystal are. And the simple light paths for fabricating 2-D and 3-D photonic crystal were designed. The light splitting elements are a mask and a top-cut prism. The experimental results indicate 2-D and 3-D photonic crystal with large-area, bulk-mass, high temperature resistance and high-strength can be fabricated using water-resisting photopolymer. It has the same photonic structures with matlab simulation. And the setup of the path is an important factor when the material is home-made water-resisting photopolymer..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 735 (2011)
Effect of External Optical Feedback Strength on Time Delay Signatures in a Semiconductor Laser with Double Optical Feedback
DING Ling, WU Jia-gui, XIA Guang-qiong, SHEN Jin-ting, LI Neng-yao, and WU Zheng-mao
Through constructing a double optical feedback semiconductor laser chaotic system, the time delay signatures of chaos are investigated experimentally under different working conditions. The results show that, time delay signatures of chaotic output can be suppressed efficiently through adjusting the feedback strength oThrough constructing a double optical feedback semiconductor laser chaotic system, the time delay signatures of chaos are investigated experimentally under different working conditions. The results show that, time delay signatures of chaotic output can be suppressed efficiently through adjusting the feedback strength of one cavity carefully and fixing the feedback strength of another cavity. Meantime, there is a big time shift which is the deviation between extracted delay time and real system delay time. Therefore, double optical feedback semiconductor laser chaotic system can efficiently hide the delay time signature of chaotic laser output, and also improve the performance in related application fields..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 740 (2011)
Characteristics of Pure Dephasing on Non-resonant Quantum Dot-cavity Coupling System and its Application Prospect
CHEN Xiang, and MI Xian-wu
The quantum dot-cavity system was investigated using a quantum master equation that took incoherent pumping, stimulated emission and pure dephasing into consideration, and analytical emission spectra at cavity and dot were presented. The theoretical analysis results show that the pure dephasing shifts the emission inteThe quantum dot-cavity system was investigated using a quantum master equation that took incoherent pumping, stimulated emission and pure dephasing into consideration, and analytical emission spectra at cavity and dot were presented. The theoretical analysis results show that the pure dephasing shifts the emission intensity towards the cavity frequency in non-resonant coupling system and thus can be a very good explanation of the non-resonantly coupled cavity effective emission effect. In order to further study the application of pure dephasing in the quantum dot-cavity coupled systems, the effective quantum dot-cavity coupling rate and the efficiency of the single photon source for detuned systems were introduced, and good cavity and bad ragime were able to be defined through comparing the effective quantum dot-cavity coupling rate and the cavity decay rate. Influence of the pure dephasing on the efective coupling rate and the efficiency of the single photon source were investigated in resonance and detuning selected two set of theoretical parameters according to the experimental data. The results show that the pure dephasing can increase the efftive quantum dot-cavity coupling and the efficiency of single photon source for detuned system and thus may make a transition from bad cavity to good cavity ragime; a set of parameters having larger coupling efficiency in a certain range can meet good cavity ragime that its single photon sources efficiency is obviously better than the other set. Compared with bad cavity regime laser in non-resonant coupling system, the good cavity regime is a necessary condition to achieve single quantum dot lasers; the Fano function shows no evidence of a maximum in the non-resonant coupling system and thus there is no laser threshold in this system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 746 (2011)
The Methods of Decreasing the Phase Noise Influence in Micro-Doppler Ladar
ZHANG Hai-yang, ZHAO Chang-ming, and YANG Su-hui
With advantages of high sensitivity and more information, coherent micro-doppler laser was especially suitable for the detection of moving targets, identification of objects’ characteristics, etc. The influence of phase fluctuation in the mode field (phase noise) on velocity accuracy was discussed in two aspects includWith advantages of high sensitivity and more information, coherent micro-doppler laser was especially suitable for the detection of moving targets, identification of objects’ characteristics, etc. The influence of phase fluctuation in the mode field (phase noise) on velocity accuracy was discussed in two aspects including linewidth and detection distance. The experimental results validated the phase noise influence on micro-doppler detection, and a new method resolving the above problems, which called range-compensated method, was proposed. In the experimental system, the laser source was monolithic non-planar ring laser with the wavelength of 1.06 μm. The micro-doppler frequency was observed by heterodyne detection, which was processed by means of time-frequency analysis. Minimum detecting velocity of the system is 0.5 mm/s, velocity resolution reaches a level of mm/s, and frequency resolution reaches a level of kHz, when the detection distance is 11 km. The results laid an experimental foundation for the practical application of micro-Doppler ladar..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 753 (2011)
Person Re-Identification Algorithm Based on Support Vector Machine Incremental Learning and Linear Programming Boosting
XU Yun-xi, JIANG Yun-liang, and CHEN Fang
Object association between the cameras is a key of persistent object tracking in non-overlapping multi-cameras. A people re-identification algorithm was proposed only using people appearance completely independent on the space-time relations, object association across disjoint views was carried out by directly utilizinObject association between the cameras is a key of persistent object tracking in non-overlapping multi-cameras. A people re-identification algorithm was proposed only using people appearance completely independent on the space-time relations, object association across disjoint views was carried out by directly utilizing identification result, and this method does not depend on captured time of object and path restrictions. Complementary visual word tree histogram and global color histogram were extracted from the video image sequence, and Support Vector Machine(SVM) incremental learning was used to train online distinguishing people appearance models of two features. Finally, multi-class Linear Programming Boosting (LPBoost) algorithm was introduced into on-line adaptive fusion of two SVM models. The proposed method has strong online learning ability, and can incrementally represent discriminative people appearance model. The model after fusing two features is more discriminative and effectively reduces the influence of changes in various conditions. Experimental results show that the proposed method achieves high identification rate and rapid real-time implementation which are markedly improved compared to the existent methods..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 758 (2011)
A Novel Detection Method of Infrared Dim and Small Target Based on Cross Window
WAN Ming, ZHANG Feng-ming, LEI Hong-li, and ZHUO Zhen-fu
To detect dim and small target in infrared image, a novel method based on cross window was presented through analyzing traditional methods. The method constructed cross detection window with up, down, left and right reference points around candidate detected point according to the size of target. Based on the grads graTo detect dim and small target in infrared image, a novel method based on cross window was presented through analyzing traditional methods. The method constructed cross detection window with up, down, left and right reference points around candidate detected point according to the size of target. Based on the grads gradient between candidate detected point and reference points, the points belong to target can be identified. The method does not need background prediction, and achieves higher detection probability and lower false alarm probability in infrared image with low signal noise ratio and strong background. Experimental results show the validity of the method..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 764 (2011)
Campus-oriented Identification System Research based on VRML
ZHANG Zhi-an
VRML technology is to simulate composed environment by means of computer multimedia technology from sense of the smelling, sight, hearing, touch and other aspects. On the operation of human-machine interaction achieve the corresponding information or experience. This paper highlights the analysis of the current applicaVRML technology is to simulate composed environment by means of computer multimedia technology from sense of the smelling, sight, hearing, touch and other aspects. On the operation of human-machine interaction achieve the corresponding information or experience. This paper highlights the analysis of the current application of VRML and its trend of development, the design and implementation of VRML based on web2.0 technology. This paper proposed a way of Campus-oriented Identification System including the design requirements of the campus-oriented identification system, infrastructure framework, development technique and the implementation method. Furthermore, modeling methods for VRML and its interactive is also concentrated..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 769 (2011)
A Novel Optimum Quantum States Entanglement Multiplexing and Relay Scheme for Land Quantum Mobile Communication
NIE Min, JIANG Jin-ya, and LIU Xiao-hui
A novel service model of land quantum mobile communication systems and the scheme of quantum multiplexing relay were proposed. The two quantum entanglement purification method, one is based on the quantum controlled-not gate, the other is based on polarizing beam splitter, were compared then. Theoretical analysis resulA novel service model of land quantum mobile communication systems and the scheme of quantum multiplexing relay were proposed. The two quantum entanglement purification method, one is based on the quantum controlled-not gate, the other is based on polarizing beam splitter, were compared then. Theoretical analysis results show that the proposed scheme can transmit quanta states with no EPR pairs shared by source and objective nodes, and the time delay in transmission has nothing to do with the number of wireless hopping and the distance of link..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 774 (2011)
Quantum Superdense Coding Scheme Based on High-dimensional Two-particles System
HUANG Ping-Wu, ZHOU Ping, NONG Liang-Qin, HE Liang-min, and YIN Cai-Liu
The author presents a generalized superdense coding scheme based on high-dimensional two particles maximally entangled state following some ideas of superdense coding scheme based on four-dimensional two particles. The quantum superdense coding based on noisy quantum channel was discussed. The receiver（Alice）can extracThe author presents a generalized superdense coding scheme based on high-dimensional two particles maximally entangled state following some ideas of superdense coding scheme based on four-dimensional two particles. The quantum superdense coding based on noisy quantum channel was discussed. The receiver（Alice）can extract dαk2logd2+logd2 (αk=minαj, j∈0,L,d－1) bits classic information by introducing one auxiliary two-level particle and perfprming corresponding unitray operation on her particles.All the parties can use some decoy photons to set up their quantum channel securely.The scheme only requires pure entangled state,which makes this scheme more convenient than others in practical application. Moreover, it has the advantage of having high communication efficiency..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 780 (2011)
Continuous Variable Phase Detection System Based on LabVIEW
ZHOU Wu-lin, and HUANG Chun-hui
A new continuous variable phase detection platform was built. In the proposed platform, electro-optic modulator was used as the transmitter to produce continuous phase shift, homodyne detection circuit was used as the receiver to measure the phase of the light field, and high performance NI data acquisition card PCI611A new continuous variable phase detection platform was built. In the proposed platform, electro-optic modulator was used as the transmitter to produce continuous phase shift, homodyne detection circuit was used as the receiver to measure the phase of the light field, and high performance NI data acquisition card PCI6111E was used to control the entire system.The LabVIEW program technologies, including PID control, DAQmx data acquisition and triangle fit, which can reduce system development time, were used to improve the programming efficiency. The feasibility of the continuous variable phase detection system was validated by Jones matrix theory and experiments, which shows the cosine relation between the output voltage of homodyne detection and the input voltage of phase modulator. The new scheme provides a new approach for continuous variable quantum key distribution..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 785 (2011)
Fabrication and Gain Measure of LaF3∶Er,Yb Doped Organic-inorganic Waveguide Amplifier
LIU Tian-ji, LI Tong, TAN Zhen-yu, CHEN Cong, SUN Xiao-qiang, and ZHANG Da-ming
Oleic acid modified LaF3∶Er,Yb nanoparticles were prepared and doped in organic-inorganic hybrid material as the active layer of waveguide amplifier. Polymethyl-methacylate-glyciclyl-methacrylate, an excellent and transparent optical polymer material, was used as the top and bottom layers. During the process of waveguiOleic acid modified LaF3∶Er,Yb nanoparticles were prepared and doped in organic-inorganic hybrid material as the active layer of waveguide amplifier. Polymethyl-methacylate-glyciclyl-methacrylate, an excellent and transparent optical polymer material, was used as the top and bottom layers. During the process of waveguide fabrication, the reason why active layer cannot be etched were instructed. And an embedded ridge structure waveguide amplifier was also designed. The device was fabricated by aluminium mask vacuum evaporation, UV lithography and reactive ion etching method (RIE) process.Waveguide end-faces were polished in order to get high gain. At last, a 3.2 dB relative gain was obtained in a 1.9 cm length sample (signal power was 1mw and pump power was 188 mW)..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 789 (2011)
Geometrical Representation of the Linear Symmetric Coupler
SHI Jian, MA Rui-qiong, WANG Chong, YANG Yi, DUAN Zuo-liang, and MIAO Run-cai
A Bloch vector model was set up using the light field electric vector in two waveguides of the liner symmetric coupler. The light “transition” process in two waveguide channels was quite directly with the Bloch vector rotation changing. It was found that the more serious the propagation constant mismatches, the faster A Bloch vector model was set up using the light field electric vector in two waveguides of the liner symmetric coupler. The light “transition” process in two waveguide channels was quite directly with the Bloch vector rotation changing. It was found that the more serious the propagation constant mismatches, the faster the frequency of light energy exchanges and the lower efficiency exchanges, which is equal to the results solved by the traditional equations..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 794 (2011)
Focusing Characteristics of Laguerre-Gaussian Radially Polarized Beam Through High Numerical Aperture
WENG Xiao-yu, GUO Han-ming, DONG Xiang-mei, SUI Guo-rong, GAO Xiu-min, and ZHUANG Song-lin
For the focusing of the optical system with high numerical aperture, the light intensity distribution in the focal region will shows some special characteristics, which can be used in many fields, such as microscopy, particles trapping, data storage etc. Based on the vectorial Deby theory, the focal light intensity disFor the focusing of the optical system with high numerical aperture, the light intensity distribution in the focal region will shows some special characteristics, which can be used in many fields, such as microscopy, particles trapping, data storage etc. Based on the vectorial Deby theory, the focal light intensity distributions of TM01 mode Laguerre-Gaussian radially polarized beam through the optical system with high numerical aperture were studied. By adjusting the ratio of the pupil radius versus beam waist, the focal light spot changed from small bright spot into dark ring spot. Moreover, by the pupil filter, the light intensity distribution in the focal region and the focal dark spot size could be modulated, which could make the intensity of dark area change from 0 to 1. And, by choosing the parameters of pupil filter purposefully, several 3D optical cages could be produced in the focal region, which made particle trapping more efficiently. Moreover, several particles can be trapped at one time, which has great practical value in trapping particles with refractive indices lower than that of surrounding medium..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 798 (2011)
Effect of the Environment on Microsphere Q-factor
ZHANG Yu-Guang, LI Peng, WANG Li, MA Pei-Jiao, YAN Ying-Zhan, LIU Jun, and YAN Shu-Bin
The Whispering Gallery Mode(WGM)optical microcavity has a wide range of applications for its high quality factor (Q). Various factors affecting the Q of optical microsphere cavities were analyzed theoretically and experimentally. WGM of microsphere with a diameter of 260 μm was achieved through coupling a tapered fiberThe Whispering Gallery Mode(WGM)optical microcavity has a wide range of applications for its high quality factor (Q). Various factors affecting the Q of optical microsphere cavities were analyzed theoretically and experimentally. WGM of microsphere with a diameter of 260 μm was achieved through coupling a tapered fiber. Experiments demonstrated that the water and dust around the microsphere cavity have great effects on the Q, which are mainly the optical absorption loss of water and scattering loss of dust, leading to 1~2 orders of magnitude lower of Q..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 40, Issue 5, 803 (2011)
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