Journals >Acta Photonica Sinica
Contents
2012
Volume: 41 Issue 3
26 Article(s)
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Research Article
Mechanisms of HF Solution Improving Damage Properties of Fused Silica Subsurface Cracks
WANG Feng-rui, ZHENG Zhi, LIU Hong-jie, HUANG Jin, ZHOU Xin-da, JIANG Xiao-dong, WU Wei-dong, and ZHENG Wan-guo
Fused silica optic was etched by HF solution, the morphology and damage properties of micro subsurface cracks were studied, and factors increased crack damage properties were explored. Finite difference time domain algorithm was used to calculate light intensification in the vicinity of cracks. Calculation results showFused silica optic was etched by HF solution, the morphology and damage properties of micro subsurface cracks were studied, and factors increased crack damage properties were explored. Finite difference time domain algorithm was used to calculate light intensification in the vicinity of cracks. Calculation results show that light intensification caused by crack contained with ZrO2 particle (diameter 50 nm) is 6.1 times of the incident light, and the maximum intensity lies inside the crack and close to the particle. However the light intensification caused by crack with the same structure and without particles inside is 3.6 times of the incident light, and the maximum intensity lies outside the crack. By HF etching, contaminations in crack are eliminated, breath depth ratio of the crack is increased, and light intensification caused by the etched crack is only 2.2 times the incident light. Experimental results also indicate that damage threshold of deeply etched crack is increased by one time, and 1 064 nm absorption of it is only 230 ppm. Damage performance of crack free area is also improved by HF ethcing, but damage threshold of the crack free area does not increase as along as etching proess goes on. It begins to decrease after reaching a maximum value, thus etching process will terminate till damage threshold of the crack free area reaches its maximum value..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 253 (2012)
Focus Location Measurement of Fiber Optic Tweezer Based on the Photothermal Effect
LI Xin-yu, LIANG Shan-shan, and SUN Chang-sen
Fiber optic tweezer is an effective method in biomedical applications that can be used to operate the objective in a microscale. It employs the moment changes when the photon passes through a small particle to generate a weak force on the particle. So the accurate control of the focus is the most important thing for thFiber optic tweezer is an effective method in biomedical applications that can be used to operate the objective in a microscale. It employs the moment changes when the photon passes through a small particle to generate a weak force on the particle. So the accurate control of the focus is the most important thing for the application of the tweezer. However, the tweezer is usually used in liquid environment. So the focus location measurement becomes extremely important and this cannot be easily obtained through the common CCD technology. In order to solve this problem, the Patch Clamp technology is employed, which has been successfully used in the electrophysiology field. In this technique, a micro pipette filled with the extracellular solution bearing a mega Ohm resistance, can give rise to a microampere current measuring accuracy. Based on the optical characteristics of the pure water and the FTIR result proves that the optical characteristics extracellular solution are quite close to pure water, 845 nm and 980 nm wavelength are chosen as the operating wavelength. The photothermal effect is generated by the solution absorbed the optical energy, and this effect can also cause the microampere current changes according to the Ohm′s law. In the experiment, the common communication fiber SMF28 is employed to fabricate a fiber-optic tweezer, and the light passes through the tweezer and incident to the solution. Following the scattering and absorption effect, the photothermal effect dominates the region of stimulation. When the micropipette filling with the solution is irradiated by the tweezer, the resistance of the micropipette will change determined by the temperature effect. Based on the scale of the micropipette, say 1 micro meter or so, the spot of the tweezer output can be measured through the micropipette movement under a precision control by a three-dimensional controller. In this way, a fine variable of the focus of the tweezer can be obtained when the wavelength switched..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 258 (2012)
Experimental Studies on NS Pulse Laser Induced Liquid plasma Shadowgraphy
LI Ming, ZHANG Hong-chao, and LU Jian
Based on the measurement principle of laser hatched method, an equipment for measure plasma shield was set up. The shielding of NS pulse laser induced breakdown in water was studied. Laser induced plasma shield images were recorded. Linear relation between the effect and laser energy was found. Linear break phenomenon Based on the measurement principle of laser hatched method, an equipment for measure plasma shield was set up. The shielding of NS pulse laser induced breakdown in water was studied. Laser induced plasma shield images were recorded. Linear relation between the effect and laser energy was found. Linear break phenomenon by the NS pulse laser was observed for the first time. These research results will provide the theoretical and experimental references for laser processing underwater, laser medicine and corresponding hydromechanics..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 263 (2012)
Passively Mode-locked Erbium Doped Fiber Ring Laser
CHEN Zu-cong, RUAN Shuang-chen, GUO Chun-yu, HU Xue-juan, and OU-YANG De-qin
By introducing the rotatable in-line polarizer into the ring cavity of nolinear polarization rotatation(NPR), the all fiber structure of passively mode-locked ring laser is simplified. The Erbium-doped mode-locked laser with the tuning range of 20 nm is achieved by adjusting the polarizer, 1/2 wave plate and the 1/4 waBy introducing the rotatable in-line polarizer into the ring cavity of nolinear polarization rotatation(NPR), the all fiber structure of passively mode-locked ring laser is simplified. The Erbium-doped mode-locked laser with the tuning range of 20 nm is achieved by adjusting the polarizer, 1/2 wave plate and the 1/4 wave plate together. Furthermore, the mode-locked pulses with dual-wavelength are observed during the tuning process. On the other hand, when removing the 1/2 wave plate from the configuration, the mode-locked laser can also be obtained by only adjusting the polarizer and the 1/4 wave plate. The tunable process is presented and analyzed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 267 (2012)
Crosstalk Analysis and Simulation of the DWDM Based Light-trail Networks
ZHANG Lei-lei, FU Ming-lei, and LE Zi-chun
Light-trail network is a novel optical network which takes advantage of mature optical devices to assign the bandwidth and switch the packets flexibly. Crosstalk is an important factor to restrict the performance at the physical layer as well as the extensibility of the light-trail network. Firstly, the causes of both Light-trail network is a novel optical network which takes advantage of mature optical devices to assign the bandwidth and switch the packets flexibly. Crosstalk is an important factor to restrict the performance at the physical layer as well as the extensibility of the light-trail network. Firstly, the causes of both interband crosstalk and intraband crosstalk in the typical light-trail nodes are discussed. In addition, the influence of the two kind’s crosstalk on the transmission performance at the physical layer is theoretically analyzed. Secondly, three methods to evaluate the crosstalk are introduced. On the basis of DWDM technique, a simulation platform with 3 nodes and 5 wavelengths is built, in which the optical devices are assigned optical depth as 20 dB and 30 dB. And the basic transmission rate of the wavelength is 2.5 Gbps. At last, the propagation process of the crosstalk is traced in the whole light-trail network. And the BER, the power penalty and the relative crosstalk are calculated accordingly. Both analytical and simulation results show that optical filter, demultiplexer and multiplexer are the key optical devices which cause crosstalks. Hence, the transmission performance of light-trail network can be enhanced obviously by improving the depth of the above optical devices. Moreover, both BER and power penalty are observed to be affected deeply by the crosstalk when the basic transmission rate of single wavelength is up to 2.5 Gbps. Therefore, the number of optical node available is limited at the scenario of DWDM..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 271 (2012)
Optimization of Two BP-based Decoding Algorithms for LDPC Codes Based on MMSE Criterion under Weak Turbulence Channel
LENG Jiao-feng, HAO Shi-qi, L Xu-guang, ZHOU Jian-guo, and ZHAO Nan-xiang
Due to high complexity of Belief Propagation(BP) algorithm, several kind of BP-based simplified decoding algorithms are analyzed. Based on the Minimum Mean Square Erro(MMSE) criterion, optimal design of the scaled BP-based and offset BP-based algorithms is discussed. The theoretical formulas and numerical calculations Due to high complexity of Belief Propagation(BP) algorithm, several kind of BP-based simplified decoding algorithms are analyzed. Based on the Minimum Mean Square Erro(MMSE) criterion, optimal design of the scaled BP-based and offset BP-based algorithms is discussed. The theoretical formulas and numerical calculations on the optimal factors for these two BP-based algorithms are provdied. The simualtion resutls for the (6,3)regualr LDPC codes of lengths 1008 on the weak atmospheric turbulence channel demonstrate that the scaeld BP-based and offset BP-based aglorithms with the proposed factors are better than Min-Sum Algorithm, and even can achieve the performance better than that of the BP algorithm,and have lower complexity compared with BP algortihm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 277 (2012)
Demodulation of Cascade Optical Fiber Fabry-Perot Pressure Sensor
JIANG Li-juan, JIANG Jun-feng, LIU Tie-gen, LIU Kun, LIU Yu, LIANG Xiao, and WANG Shao-hua
Through analysing the spectrum of the cascade optical fiber Fabry-Perot pressure sensor composed with three reflecting surfaces, the lower envolope of the spectrum can be used to demodulate the sensor′s cavity length. A novel algorithm based on fitting of interference-order is proposed. Simulation analysis is carried oThrough analysing the spectrum of the cascade optical fiber Fabry-Perot pressure sensor composed with three reflecting surfaces, the lower envolope of the spectrum can be used to demodulate the sensor′s cavity length. A novel algorithm based on fitting of interference-order is proposed. Simulation analysis is carried out with the cavity length of F-P2 variating between 160 μm to 215 μm. It is shown that the results precision can be improved using the novel method at the different signal to noise ratio (SNR), and is not impacted by sensor′s cavity length and the optical spectrum resolution ratio at the same SNR. The experiment is also carried out, and the calculation results show that the residuals of the least square curve fitting is 0.012 μm, which verify the effectiveness of the new algorithm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 283 (2012)
Research on Interactions Between Solitary Waves in Negative-index Materials
CHEN Cheng, DONG Jia, and YANG Rong-cao
Based on the higher-order nonlinear Schrdinger equation describing the propagation of ultrashort pulses in negative-index materials, the interactions of bright and dark solitary waves in negative-index materials are studied using symmetrical Split-step Fourier method, respectively. Lots of numerical results show that Based on the higher-order nonlinear Schrdinger equation describing the propagation of ultrashort pulses in negative-index materials, the interactions of bright and dark solitary waves in negative-index materials are studied using symmetrical Split-step Fourier method, respectively. Lots of numerical results show that when initial frequency shift is zero, the interactions between bright solitary waves are similar to those of bright solitons in conventional materials; when initial frequency shift is nonzero, the transmission speed and interactions are influenced by the third-order dispersion and the self-steepening effects. While the interactions between dark solitary waves are similar to those of dark solitary waves in conventional materials behaving repulsion each other under the influence of the third-order dispersion and the self-steepening effects whether initial frequency shift is zero or not. The results show that the interactions of bright and dark solitary waves in negative-index materials may be suppressed to some extent. The obtained results provide a theoretical basis for the applications of negative-index materials in future high-speed communication..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 288 (2012)
Fiber Spatial Coupler of About 1∶1 Ratio Constituted by Aspherical Lens
WEN Wu-qi, KANG Jian-yi, DING Xin, LU Ying, YANG Peng-fei, FU Xiang-yong, NING Ding, and YAO Jian-quan
For the aim of the fiber pump coupling, calculation and experiment are carried out for the fiber 1∶1 spatial coupler composed of two aspherical lens. Optical pathway is analyzed according to the variation regularity of Gaussian beam. According to the poor coherence of the LD output beam, ray tracing calculation is carrFor the aim of the fiber pump coupling, calculation and experiment are carried out for the fiber 1∶1 spatial coupler composed of two aspherical lens. Optical pathway is analyzed according to the variation regularity of Gaussian beam. According to the poor coherence of the LD output beam, ray tracing calculation is carried out for the optical pathway diagrams of the coupler. It can be found that the coupler constituted with ellipsoid lens is more stable than that with hyperboloid lens in the case of the wavelength changing and so on. The aspherical lens that meets the calculation result is chosen to constitute the coupler. The couplers with transmittance of 95% composed for the experiments demonstrated a coefficient of 90% LD coupling into a length of multimode fiber with core diameter of 200 micro-meter without antireflection coating at the end surface..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 294 (2012)
Design and Fabrication of Satellite Laser Communication Filter Coating
ZHANG Jing, FU Xiu-hua, and PAN Yong-gang
In order to satisfy the special requirements of super velocity data transmission in satellite laser communication, a type of multi-band filter membrane with high reflection at 532 nm, 632 nm, 1 064 nm wavelengths and high transmission at 808 nm, 1 550 nm wavelengths is prepared, adopting electronic beaming vacuum deposIn order to satisfy the special requirements of super velocity data transmission in satellite laser communication, a type of multi-band filter membrane with high reflection at 532 nm, 632 nm, 1 064 nm wavelengths and high transmission at 808 nm, 1 550 nm wavelengths is prepared, adopting electronic beaming vacuum depositing method with the aid of ion assistant deposition technology. By selecting H4 and SiO2 as the high and low refractive index materials, continually optimizing the film system design curve, reducing the number of sensitive layers, the film structure is obtained that is easily prepared. The thin films are prepared through electron beam heating evaporation and ion assisted deposition system, and the film thickness is controlled using crystal-controlled and light control monitoring methods at the same time. By continually adjusting the process, the film laser damage resistance ability is improved, the control error is reduced, the transmittance of the transmission band and the reflectance of the reflection band are increased, and the filter membrane with better spectral performance is obtained. The experimental results show that the filter membrane can withstand rain, salt spray, high and low temperature and other environments, and meet the requirements in satellite laser communication..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 303 (2012)
Hydrogen Dilution Affect on Growth And Optical Properties of Amorphous Silicon (a-Si∶H) Film with FTS
YU Wei, LI Bin, GUO Shao-gang, ZHAN Xiao-zhou, DENG Wen-ge, and FU Guang-sheng
Hydrogenated amorphous silicon films were deposited by facing target sputtering with different hydrogen dilution ratio with H2 as reaction gas.The growth rate and the optical properties of a-Si∶H films with different hydrogen dilution ratio were characterized by surface profiler, Fourier-transform infrared spectroscopyHydrogenated amorphous silicon films were deposited by facing target sputtering with different hydrogen dilution ratio with H2 as reaction gas.The growth rate and the optical properties of a-Si∶H films with different hydrogen dilution ratio were characterized by surface profiler, Fourier-transform infrared spectroscopy, Raman scattering and ultraviolet-visible transmittance spectrum. It was found that, the low temperature and high deposition of a-Si∶H films can be deposited by facing target sputtering method. With increasing hydrogen dilution, a trend that the deposition rate of a-Si∶H films first decreases and then increases is showed. Fourier transform infrared transmission spectra show that hydrogen content of a-Si∶H films increases first and then becomes smaller. While, through analysising the Raman spectra and UV-visible light transmission spectrum, the degree of order and the optical band gap also first increase and then decrease. Obviously, the film structure can be effectively controlled by the change of the hydrogen dilution with this technology..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 307 (2012)
1×2 Optical Drop Splitter in a Rod-type Silicon Photonic Crystal
LIN Gui-min, CHEN Xi-yao, LI Jun-jun, and ZHUANG Dong-xia
Based on a self-collimation ring resonator (SCRR) in a rod-type silicon photonic crystal, a 1×2 optical drop splitter (ODS) with selected splitting ratio is proposed. The 1×2 ODS consists of three beam splitters and one mirror, and light propagates in the ODS employing self-collimation effect. The theoreticalBased on a self-collimation ring resonator (SCRR) in a rod-type silicon photonic crystal, a 1×2 optical drop splitter (ODS) with selected splitting ratio is proposed. The 1×2 ODS consists of three beam splitters and one mirror, and light propagates in the ODS employing self-collimation effect. The theoretical transmission spectra at different drop ports of the ODS are analyzed with the multiple-beam interference theory, and they were investigated with the finite-difference time-domain (FDTD) simulation technique. The simulation results agree well with the theoretical prediction. For the drop wavelength 1 550 nm, the free spectral range of the ODS is about 30 nm, which almost covers the whole optical communication C-band window. Because of their small dimensions and whole-silicon material, the proposed ODSs hold great potentials for applications in photonic integrated circuits (PICs)..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 311 (2012)
Characteristics of Photonic Crystal Biber for Hydraulic Pressure Sensing
HE Zhong-jiao
A side-hole photonic crystal fiber for (hydrostatic) pressure sensing was proposed to achieve compact and high sensitivity fiber based pressure sensor. The effective index, mode profile and the stress property of a conventional photonic crystal fiber and the side-hole photonic crystal fiber were investigated based on aA side-hole photonic crystal fiber for (hydrostatic) pressure sensing was proposed to achieve compact and high sensitivity fiber based pressure sensor. The effective index, mode profile and the stress property of a conventional photonic crystal fiber and the side-hole photonic crystal fiber were investigated based on a full-vector finite-element method. Due to the photoelastic effect, the hydrostatic pressure induced index changes of the conventional photonic crystal fiber and the side-hole photonic crystal fiber were presented. Simulation results show that the side-hole photonic crystal fiber can achieve higher pressure sensitivity, and the pressure sensitivity increases together with the radius of big air holes of the side-hole photonic crystal fiber. Thus, the structure-optimized side-hole photonic crystal fiber can be used as a high sensitivity (hydrostatic) pressure sensor..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 316 (2012)
An Image Dehazing Method Based on Weighted Dark Channel Prior
LIU Nan, CHENG Yong-mei, and ZHAO Yong-qiang
The classical method based on dark channel prior only considers the estimated transmission map and does not take into account the depth information to optimize the soft matting function, which makes the result contain few halo artifacts in depth discontinuity and haze-removal effect in the region far from the viewpointThe classical method based on dark channel prior only considers the estimated transmission map and does not take into account the depth information to optimize the soft matting function, which makes the result contain few halo artifacts in depth discontinuity and haze-removal effect in the region far from the viewpoint is degraded. For this issue, a simple but efficient image dehazing method is proposed with weighted dark channel prior based on edge feature. Using this method, depth continuity can be estimated by position of edge points, and refined transmission map is obtained by different weight of edge points and non-edge points. Experimental results show that detail information is well preserved and no halo artifacts in haze-free image, and demonstrates the feasibility and effectiveness of the proposed algorithm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 320 (2012)
Color Image Encryption Based on Double Random Phase Encoding
QIN Yi, and ZHENG Chang-bo
For the purpose of color image encryption using two keys, a method based on grating modulation is proposed. First of all, a color image is separated into three components: red, green, and blue. The three grey images are multiplied by sine gratings with different spatial frequencies, and a superposition of the modulatedFor the purpose of color image encryption using two keys, a method based on grating modulation is proposed. First of all, a color image is separated into three components: red, green, and blue. The three grey images are multiplied by sine gratings with different spatial frequencies, and a superposition of the modulated results is introduced. Thus a real-valued target image that contains the whole information of the color image is obtained. Then the target image is encrypted using double phase encoding system, which means the original color image is encrypted. Due to the introduction of the sine gratings, the R, G, B frames are able to be spatially separated, so the color map can be reconstructed and the original color image can be recovered. Both theoretical analysis and simulations are proposed, and the validity of this method is verified by experimental results..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 326 (2012)
Quantum Controlled Teleportation of an Arbitrary m-particle State Using a (2m+1)-particle Entangled State as Quantum Channel
LI Hong-wei, LONG Liu-rong, ZHOU Ping, and YIN Cai-liu
A general scheme for controlled teleportation of an arbitrary m-qubit (high-dimensional quantum system) state with a d-dimensional (2m+1)-particle entangled state is presented. The arbitrary m-qubit state can be teleported if the sender (Alice) performs m generalized Bell state measurements on his particles and the conA general scheme for controlled teleportation of an arbitrary m-qubit (high-dimensional quantum system) state with a d-dimensional (2m+1)-particle entangled state is presented. The arbitrary m-qubit state can be teleported if the sender (Alice) performs m generalized Bell state measurements on his particles and the controller (Bob) performs single particle generalized X-basis measurement on his particle. The original m-qubit state can be reconstructed on the receiver′s particles if the receiver (Charlie) performs corresponding unitary operations on his particles according to the measurement results of the sender and the controller. The scheme has the advantage of transmitting much less particles for controlled teleportation of an unknown m-qubit state than others. Moreover, the application of the scheme by using a nonmaximally entangled state as its quantum channel is discussed. The original m-qubit state can be probabilistically reconstructed on the receiver′s particles if the receiver introduces an auxiliary qubit and performs the general unitary transformation on his entangled particles and the auxiliary qubit. The relationship between the success probability that the receiver obtains the originally m-qubit state and the coefficients of the pure entangled quantum channel is also discussed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 330 (2012)
Remote State Preparation of Arbitrary Three-qubit State via Cluster State and Bell State
WANG Dong, ZHA Xin-wei, QI Jian-xia, and HE Yao
A novel scheme for remote preparation of an arbitrary three-qubit state using four-qubit cluster state and Bell state is proposed. The three-particle state can be perfectly prepared if the sender (Alice) performs the orthogonal complete measurement on her particles and the receiver (Bob) introduces an appropriate unitaA novel scheme for remote preparation of an arbitrary three-qubit state using four-qubit cluster state and Bell state is proposed. The three-particle state can be perfectly prepared if the sender (Alice) performs the orthogonal complete measurement on her particles and the receiver (Bob) introduces an appropriate unitary transformation on his particles. For the two cases of remote state preparation, two different projective measurement bases are constructed at sender′s side and the corresponding success probabilities are calculated. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. It is that in general such remote state preparation can be realized with a probability of 1/8. But in several special cases, the probability of success can be improved to 1/4, 1/2 or even 1..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 335 (2012)
The Damage Model of Quantun Signaling of Multi-user Based on Malicious Attack and Repair Strategy
LI Chao, NIE Min, and LIU Xiao-hui
A quantum signaling transmission system of multi-user is presented, and the transmission process signaling channel is introduced. The damage model maliciously attacked by the third party is analyzed in the transmission process, and the idea of decoy state is introduced to the safety of quantum signaling in direct commuA quantum signaling transmission system of multi-user is presented, and the transmission process signaling channel is introduced. The damage model maliciously attacked by the third party is analyzed in the transmission process, and the idea of decoy state is introduced to the safety of quantum signaling in direct communication. To overcome photon number splitting(PNS) attack, light pulses are sent using different light intensities, which also improve the safety of the signal transmission. The simulation result shows that repair strategy of multi-user quantum signaling transmission system being attacked can effective detect the PNS attack,and increase distance of security transmission, to ensure the signaling transmission process safely and effectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 339 (2012)
Entanglement Properties in the System of two Atoms Trapped in Coupled Cavities
LU Dao-ming
The two-excitation system comprising two two-level atoms resonantly interacting with two coupled cavities is analyzed. The evolution of the state vector of the system is given when the total excitation number equals two. By means of the numerical calculations, the temporal evolution in the entanglement is investigated The two-excitation system comprising two two-level atoms resonantly interacting with two coupled cavities is analyzed. The evolution of the state vector of the system is given when the total excitation number equals two. By means of the numerical calculations, the temporal evolution in the entanglement is investigated between the atoms, between the cavities, as well as between the atom and the local cavity mode. The influences of coupling constant between cavities on the entanglements are discussed. The results obtained show that atom and atom are separable, and the cavity-cavity entanglement and the atom-cavity entanglement are weakened with increasing of the coupling constant between cavities..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 343 (2012)
Entanglement Properties of Three Two-level Atoms System Interacting with a Fock State Field
LIAO Qing-hong, and GONG Li-hua
The dynamics of entanglement of three two-level atoms initially in GHZ state system interacting with a Fock state field are investigated by means of concurrence and linear entropy. The effect of photon number on the time evolution of concurrence and linear entropy is analyzed. The results show that the phenomenon of suThe dynamics of entanglement of three two-level atoms initially in GHZ state system interacting with a Fock state field are investigated by means of concurrence and linear entropy. The effect of photon number on the time evolution of concurrence and linear entropy is analyzed. The results show that the phenomenon of sudden birth of entanglement between two atoms trapped in a cavity occurs and the threshold time and maximum for the creation of the entanglement can be controlled by the photon number. The measurement of the atom outside the cavity leads to the periodic evolution of the concurrence and an increase of the photon number results in decreasing in the maximum of concurrence and shortening of the evolution period of the time behavior of concurrence..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 348 (2012)
Bidirectional Reflection Characteristics of Honeycomb Cell in Baffle
CHEN Xue, SUN Chuang, and XIA Xin-lin
Honeycomb structure on the inner wall of baffle dominates the performance of stray light suppression of the baffle. It is significant to understand the anisotropic radiation transfer characteristics of the honeycomb cell for stray light analysis and optimum design of baffle. A numerical model of radiative propagation wHoneycomb structure on the inner wall of baffle dominates the performance of stray light suppression of the baffle. It is significant to understand the anisotropic radiation transfer characteristics of the honeycomb cell for stray light analysis and optimum design of baffle. A numerical model of radiative propagation was built for honeycomb cell and the discrete BRDF expression was deduced for the equivalent surface. By simulating the stray light propagation with the Monte Carlo method, the effects of geometric parameters and reflectivity of coating on BRDF of the equivalent surface were analyzed. Based on the obvious backscattering of the honeycomb structure predicted by the BRDF analysis, the probability model of anisotropic reflection was established for the equivalent surface. The BRDF results predicted by the probability model show good agreement with that of the direct simulation, and it can be well used in stray light analysis and design of baffle..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 353 (2012)
Design of Zoom Optical System with Long Focal Length and Super-high Zoom Ratio
LI Hong-zhuang, ZHANG Zhen-duo, CAO Jing-tai, LIU Xin-yue, LI Hong-wen, and WANG Jian-li
In order to design an optical system with focal length range from 17 to 1 700 mm, a proper initial optical layout is selected first, the rule of system performance influenced by Guassian solution is found through comparing Guassian optical calculation results, and the key parameters of the system are selected. Then theIn order to design an optical system with focal length range from 17 to 1 700 mm, a proper initial optical layout is selected first, the rule of system performance influenced by Guassian solution is found through comparing Guassian optical calculation results, and the key parameters of the system are selected. Then the configuration of each assembly is chosen through analyzing the relative aperture and characteristics of aberrations, and the system aberration is corrected and balanced. The total track of the result lens is 760 mm, the modulation transfer functions at 50 lp/mm for each zoom configurations and all fields of view are greater than 0.3, and all indexes satisfy the command of system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 358 (2012)
Design of a Large Array CMOS Image and Display System in Real-time Synchronization
SU Wan-xin
In order to achieve real-time imaging and simultaneous display, a lary array CMOS camera system with simple structure and portable size is designed. Making use of EPF10K50, image timing of MT9M413C36STM, display timing of SXGA and multiplex of output data are designed. Image sensor data is divided into two way signals.In order to achieve real-time imaging and simultaneous display, a lary array CMOS camera system with simple structure and portable size is designed. Making use of EPF10K50, image timing of MT9M413C36STM, display timing of SXGA and multiplex of output data are designed. Image sensor data is divided into two way signals. One way data outputs for processor electric circuit to deal with, the other way data through ADV7127 video AD transformation outputs to display simultaneity in SXGA. The related hardware electric circuit is designed, and the device driver is written using the VHDL language. Under the development environment of the Quartus 8.0, it is debugged. Experimental results show that this system can stably work in 1 280×1 024@60 Hz line-by-line scan..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 364 (2012)
Spectrum′s Characteristics of Bone Tissues on Pedicle Screw Placement Pathway
ZHANG Shuang, LI Wei-tao, WANG Xue-na, and QIAN Zhi-yu
The characteristic identification factor of the vertebra at different positions was studied by spectroscopic technology. The spectral measurement system consists of computer, the integrated hand drill with dual-fiber probe (each fiber′s core diameter is 200 μm and the distance between the center of two fibers is 0.5 mmThe characteristic identification factor of the vertebra at different positions was studied by spectroscopic technology. The spectral measurement system consists of computer, the integrated hand drill with dual-fiber probe (each fiber′s core diameter is 200 μm and the distance between the center of two fibers is 0.5 mm), halogen light source (wavelength is from 360 nm to 2 000 nm) and fiber optic spectrometer (detection wavelength: 200~1 100 nm). The diffuse reflectance spectrum and the reduced scattering coefficient of biological tissue could be obtained at the same time. Pig′s vertebra was chosen as experimental subject to measure the diffuse reflectance spectrum and scattering coefficient of different bone tissue on pedicle screw placement pathway. The characteristic identification factor was defined by analyzing the peak values, the size of the area and the slope of the spectrum in specific wavelength. We find that different bone tissue′s spectrums show different characteristics. The change of the peak values was 1.77 and the change of the area values was 2.13 times higher than that of scattering coefficient, respectively. At the range of 495 nm to 505 nm, the slope of spectrum of cortical bone and cancellous bone was positive. At the range of 520~535 nm, the slope of spectrum of cortical bone was positive, and the slope of cancellous bone was negative. It can be concluded that the peak value, the area and the slope obtained by analysis of spectrum′s characteristics could distinguish the difference between cortical bone and cancellous bone..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 370 (2012)
An Opt-electronic Method for Inspecting Foreign Particles in Injections
WANG Fu-yu, HUANG Mei-zhen, ZENG Tao, GUAN Xiang-yu, SUN Xiao-xiao, and WANG Yang
In the production process of the injection, foreign particles are probably interfused into the injections, so the injections must be inspected before leaving the factory. An opt-electronic method is proposed based on light-blocking theory for foreign particles detected in injections, and the principle of this inspectinIn the production process of the injection, foreign particles are probably interfused into the injections, so the injections must be inspected before leaving the factory. An opt-electronic method is proposed based on light-blocking theory for foreign particles detected in injections, and the principle of this inspecting method is introduced. Compared with the conventional manual inspection method, the preliminary experimental results show that the new method has a satisfied conformance rate of 96.30% in the case of static offline detection. In order to improve the inspection effect, a method of dual-light-path is also proposed to avoid the foreign particles miss inspection in case of the track testing time is too short or the testing area is too small..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 375 (2012)
Design and Fabrication of a 1-by-4 Multimode Interference Couplers Based on InP
Ma Li, Zhu Hongliang, Chen Minghua, Zhang Can, Wang Baojun, and Bian Jing
Multiple wavelength DFB laser array and multimode interference coupler integrated light source device has important application prospect in the dense wavelength division multiplexing system. A strongly guided InP/InGaAsP multimode interference coupler is designed and simulated by using 3D FD-BPM method in order to reseMultiple wavelength DFB laser array and multimode interference coupler integrated light source device has important application prospect in the dense wavelength division multiplexing system. A strongly guided InP/InGaAsP multimode interference coupler is designed and simulated by using 3D FD-BPM method in order to research the optical coupler used in the broadband available multiple wavelength integrated light source. Tapered input/output waveguides are used to reduce the insertion loss of the multimode interference coupler and to improve the uniformity of the output ports. Combined with the metal organic chemical vapor deposition (MOCVD) epitaxial growth apparatus and according to the simulation results, a 1-by-4 multimode interference coupler is fabricated by using reactive ion etching process. The insertion loss and the uniformity of the device is measured by automatic alignment waveguide coupling test system. The test result shows that the device has 40nm available bandwidth and 2.6dB pass band flatness around 1550nm.Furthermore, the insertion loss is no higher than 10dB at the designed wavelength 1550nm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 3, 299 (2012)
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