Journals >Acta Photonica Sinica
Contents
2013
Volume: 42 Issue 6
23 Article(s)
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Research Article
Design of Silicon-on-insulator Ultra-small Micro-ring Resonator Microwave Photonics Phase Shifter
WANG Wei, YANG Li-jun, WU Wei, FENG Qi, BAI Chen-xu, FENG Shi-juan, and WANG Zhen
A ultra-small micro-ring phase shifter based on the silicon-on-insulator (SOI) material is designed. 2π phase shift in the free spectral range and optimal linearization is achieved. According to the phase shift characteristics of the micro-ring resonator all-pass phase structure, phase shift of the micro-ring is π at tA ultra-small micro-ring phase shifter based on the silicon-on-insulator (SOI) material is designed. 2π phase shift in the free spectral range and optimal linearization is achieved. According to the phase shift characteristics of the micro-ring resonator all-pass phase structure, phase shift of the micro-ring is π at the critical coupling area and 2π in the over coupling area. Two parameters (straight waveguide width and spacing) of the micro-ring are investigated which affect the phase shift. Finesse F also is used as a parameter for spacing, and micro-ring resonator’ phase shift combined with the power of change is discussed. The experimental results show that the designed micro-ring phase shifter can achieve the RF phase shift of 0～4 rad, and RF power variation is less than 6 dB with a 40 GHz RF signal..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 631 (2013)
Fabrication of Integral Type Cold Cathode with Carbon Nanotube for Improving the Electrical Contact and Adhesion Performance
LI Yu-kui, WANG Feng-ge, LIU Xing-hui, LU Wen-ke, and ZENG Fan-guang
On cathode glass faceplate the new integral type cold cathode was developed. The printed silver slurry was sintered to form the silver bottom electrode. The thin-layer bottom electrode paste including a great deal of carbon nanotube was prepared, and was screen-printed on the silver bottom electrode surface. The ordinaOn cathode glass faceplate the new integral type cold cathode was developed. The printed silver slurry was sintered to form the silver bottom electrode. The thin-layer bottom electrode paste including a great deal of carbon nanotube was prepared, and was screen-printed on the silver bottom electrode surface. The ordinary carbon nanotube paste was fabricated on the baked thin-layer bottom electrode paste. The two types of pastes were simultaneous sintered in the sintering furnace with the protection of high purity argon atmosphere. The sintered thin-layer bottom electrode would combine with the silver bottom electrode, which the carbon nanotube layer was covered on its surface. In one cathode pixel there were two carbon nanotube field emitters. Due to the spare carbon nanotube field emitter, the service life of field emission display could be prolonged greatly. Using thin-layer bottom electrode as interface layer between the silver bottom electrode and the carbon nanotube layer, the adhesion property of carbon nanotube was improved and the reliable ohmic contact had also been confirmed. With carbon nanotube as cathode material, the integral type cold cathode field emission display was fabricated, which exhibited good luminescence image quality and better field emission characteristics. Comparing with the ordinary carbon nanotube cathode field emission display, the turn-on electric-field could be reduced from 2.11 V/μm to 1.68 V/μm, the maximum field emission current could be enhanced from 905.7 μA to 1 866.2 μA, and the field emission current fluctuation at 367 μA would not exceed 4.5%. The integral type cold cathode field emission display has subsequently been operated for more than 10 days with stable luminance brightness..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 637 (2013)
Optical Properties Comparison of Two Multiwalled Carbon Nanotubes with Different Growth Techniques
YUAN Yan-hong, KE Lei, and YANG Dang-qiang
The multiwalled carbon nanotubes (MWNTs) are synthesized by a chemical vapor deposition and an arc discharge, and their configurations are shown by the scanning electron microscope(SEM) graph. The optical properties of the samples were measured by using of Raman spectra, the absorption spectra and fluorescence spectra.The multiwalled carbon nanotubes (MWNTs) are synthesized by a chemical vapor deposition and an arc discharge, and their configurations are shown by the scanning electron microscope(SEM) graph. The optical properties of the samples were measured by using of Raman spectra, the absorption spectra and fluorescence spectra. The SEM graph shows that the carbon nanotube synthesized by a chemical vapor deposition has less impurities and defects and greater diameter. The absorption spectra confirm that absorption peaks of the two samples are both at 250 nm. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths. When the wavelength of the excitation light is at 248 nm, an emission band at about 480 nm is observed in the PL spectra to the samples synthesized in the two ways mentioned above and more intensive by the former one; but when the excitations at 550 nm are used the peak located at 820 nm appears only for the sample synthesized by a chemical vapor deposition..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 645 (2013)
Diffusion Processing and Its Matching Property of Multicrystalline Silicon Solar Cells Through Reactive Ion Etching Texturing
DOU Wei-jiang, QIN Ying-xiong, JU Xiao-bao, LI Kai, and XU Ting
The matching property of multicrystalline silicon wafers through its reactive ion etching (RIE) texturing with diffusing process was studied. Under the same diffusion processing, the value of sheet resistance of multicrystalline silicon wafers through RIE texturing is 3 to 11 Ω/□ which is higher than that through acid The matching property of multicrystalline silicon wafers through its reactive ion etching (RIE) texturing with diffusing process was studied. Under the same diffusion processing, the value of sheet resistance of multicrystalline silicon wafers through RIE texturing is 3 to 11 Ω/□ which is higher than that through acid texturing. Additionally, the uneveness of the sheet resistance through RIE texturing is close to 80% of that through acid texturing. For the band of 340~1 000 nm, the external quantum effeciency of the solar cells through RIE texturing is about 10% higher than that of multicrystalline silicon solar cells through acid texturing. The electrical performace of multicrystalline silicon solar cells through RIE texturing was analyzed, and the matched diffusing process with high sheet resistance was put forward. By optimizing adjustment diffusing process, under the condition of the sheet resistance of 80 Ω/□ , the efficiency of multicrystalline silicon solar cells through RIE texturing has been increased to 17.51%, and it was 0.5% higher than that of multicrystalline silicon solar cells through acid texturing cells..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 649 (2013)
Media Access Control Protocol Design in OFDM-PON
QIAO Yao-jun, DING Fu-ling, and JI Yue-feng
A novel media access control protocol is proposed based on EPON considering of the character of orthogonal frequency-division multiplexing passive optical network. Multi-point control protocol, control message format and the priority of services are designed and a dynamic bandwidth allocation algorithms is proposed, whA novel media access control protocol is proposed based on EPON considering of the character of orthogonal frequency-division multiplexing passive optical network. Multi-point control protocol, control message format and the priority of services are designed and a dynamic bandwidth allocation algorithms is proposed, which supports multi-service access and ensures quality of service distinguishing user level in specified case. The proposed algorithm uses two-level mechanisms and the allocating progress can be divided into two steps-schedule for different priority of services and schedule for different level optical network unit. The proposed protocol is simulated and the results of delay, packet loss ratio and throughput performance show that the proposed protocol guarantees the quality of service requirements for different services excellently, and meets quality of service requirements of multi-service access..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 654 (2013)
Parallel Traffic Migration of Restoration in PCE-based Optical Networks
ZHANG Yin, LU Jian-guo, HUANG Shan-guo, LI Xin, ZHANG Min, ZHAO Yong-li, ZHANG Jie, and GU Wan-yi
The problem about the parallel traffic migration in recovery of the optical network based on path computation element is studied under the condition that the backup lightpaths cannot be setup using present available resources without traffic migration. A mathematical model is established, and the parallel traffic migraThe problem about the parallel traffic migration in recovery of the optical network based on path computation element is studied under the condition that the backup lightpaths cannot be setup using present available resources without traffic migration. A mathematical model is established, and the parallel traffic migration is realized. A heuristic algorithm is provided to obtain the order of restoration in parallel traffic migration,which is composed of dependence graph partition and lightpath sorting by minimizing the max number of the required resource of disrupted connections algorithm. The simulations show that minimizing the max number of the required resource of disrupted connections algorithm can significantly shorten the duration of the traffic migration in recovery with acceptable cost..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 661 (2013)
Bayesian Classifier Based Service-aware Mechanism in 10G-EPON for Smart Power Grid
BAI Hui-feng, LI Ming-wei, and WANG Dong-shan
With emerging of multiple services brought by smart power grid, the rapid evolution of 10G-EPON (10 Gigabit Ethernet Passive Optical Network) provides great access for multiple services with high capacity. However, newly emerging multiple services have diversified characteristics and demands, which presents great problWith emerging of multiple services brought by smart power grid, the rapid evolution of 10G-EPON (10 Gigabit Ethernet Passive Optical Network) provides great access for multiple services with high capacity. However, newly emerging multiple services have diversified characteristics and demands, which presents great problems for current 10G-EPON to match these services with high quality and matching degree. To satisfy requirements of diversified types of services in power electirc system, services charactrisetcs and demands of smart power grid are discussed, and a Bayesian Classifier based Service Awareness (BC-SA) mechanism of 10G-EPON is proposed for smart power grid. According to the “master-slave” architecture between OLT (Optical Line Terminal) and ONUs (Optical network Units) in 10G-EPON, a similar “master-slave” structure is adopted and designed in the proposed BS-SA mechanism. By using Bayesian classifier, the BC-SA mechanism is able to be aware of the type of service. On the basis of Bayesian classification, resources allocation and transport policy are both determined by the proposed mechanism throught cooperation between OLT and ONUs. In order to verify the reasonability of this BC-SA, system simulation is conducted in domains of delay and packet-loss-rate. Simulation results show that the BC-SA is able to achieve greatly better performance of both delay and packet-loss-rate, and improve the supporting ability for data services of smart power grid with better matching degree..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 668 (2013)
Characteristics for the Soliton Based on Nonlinear Schrdinger Equation
WEI Jian-ping, WANG Jun, JIANG Xing-fang, and TANG Bin
For the problems of the attenuation and the dispersion in long distance fiber communication of optical information, the optical soliton communication is an effective method. The flexible soliton solution has been obtained from the solution of the nonlinear Schrdinger equation with the group-velocity dispersion, linearFor the problems of the attenuation and the dispersion in long distance fiber communication of optical information, the optical soliton communication is an effective method. The flexible soliton solution has been obtained from the solution of the nonlinear Schrdinger equation with the group-velocity dispersion, linear potential, three-order nonlinearity term, and the gain/loss term. A trial solution that was a travelling wave solution with complex amplitude was used and it was replaced into the nonlinear Schrdinger equation. The three new variables were introduced after the nonlinear Schrdinger equation was separated into imaginary part and real part. Finally the square of wave-function of soliton solution and the consequence figures was got with Matlab. The results show that the soliton solution is sensible for various parameters. The appropriate soliton was obtained by reasonable parameters choice and it made the foundation for the soliton communication in the optical fiber..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 674 (2013)
Spectroscopic Properties of Ytterbium-doped TeO2-Al2O3-Cs2O Glass
YANG Li-quan, ZOU Kuai-sheng, YUAN Xiao, XIONG Bao-xing, QIN Zhong-xue, ZHANG Xiang, and ZHANG Gui-ju
A kind of Yb3+-doped tellurite glass with the composition of 80TeO2-10Al2O3-10Cs2O-xYb2O3 (x=0~1.6)(mol%) was prepared by conventional melt-quenching method. The dependence of the density, thermal expansion coefficient and refractive index of the glass with wavelength were measured. The absorption spectra, fluorescenceA kind of Yb3+-doped tellurite glass with the composition of 80TeO2-10Al2O3-10Cs2O-xYb2O3 (x=0~1.6)(mol%) was prepared by conventional melt-quenching method. The dependence of the density, thermal expansion coefficient and refractive index of the glass with wavelength were measured. The absorption spectra, fluorescence spectra and fluorescence lifetimes of samples doped with different concentrations of Yb3+ ions were studied. The stimulated emission cross-sections (σemi) of Yb3+ ions from 2F5/2 level to 2F7/2 level in the samples were calculated with the McCumber theory. The results indicate that the emission cross-section of the glass for the Yb2O3 doping level of 1 mol% is 1.06×10－20 cm2 at 1 004 nm, its fluorescence effective bandwidth is about 89.6 nm, and the fluorescence lifetime reaches the maximum of 0.80 ms. The laser performance assessment results show that the glass is a potential candidate for ultra-short pulse lasers..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 679 (2013)
Photon Correlation Spectroscopy for Nano-particle Diameter Measurement with Weighted Nonnegative Least Squares
SHAN Liang, and KONG Ming
To reduce the effect of noise on inversion result of grain diameter in nano-particle diameter measurement using photon correlation spectroscopy, a nano-particle diameter computing method is proposed based on photon correlation spectroscopy with nonnegative least squares. Photon correlation spectroscopy itself is as theTo reduce the effect of noise on inversion result of grain diameter in nano-particle diameter measurement using photon correlation spectroscopy, a nano-particle diameter computing method is proposed based on photon correlation spectroscopy with nonnegative least squares. Photon correlation spectroscopy itself is as the weight to derive discrete model of inversion algorithm and avoid the influence of data fluctuation close to zero. The 90 nm, 190 nm and mixed latex particles are measured by the photon correlation spectroscopy equipment and compared with the traditional nonnegative least squares. The 30 experimental data in 60 seconds indicate that in the inversion of unimodal paticle group, the results of present method is close to traditional nonnegative least squares but variance of multiple repeated measurement is smaller which proves good repeatability of present method; in the inversion of multimodal particles, the results of present method are much closer to true values of diameters, however, the results of nonnegative least squares deviate more from true values. Experimental data of different measurement time show that in a short period of time, variance of present method is smaller and it can obtain more accurate results in a shorter period of time..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 684 (2013)
Design and Analysis of a Kind of Novel Left-handed Metamaterial
YI Qiang, ZHOU Fu-kun, and LUO Xing-fang
A novel wide-band left-handed metamaterial structure is designed based on the theory of the LHM , which is composed of a copper wire and a resonator with closed-rectangular ring which has a cross wire inside. Resonators are used to achieve negative permeability and wires are used to achieve negative permittivity in theA novel wide-band left-handed metamaterial structure is designed based on the theory of the LHM , which is composed of a copper wire and a resonator with closed-rectangular ring which has a cross wire inside. Resonators are used to achieve negative permeability and wires are used to achieve negative permittivity in the new structure. The permeability and the permittivity are simultaneously negative, namely, the effective refraction is negtive and the wave impendence is positive within certain band by proper design. Numerical simulated results show that there has a passband within operating frequency. The real part of effective refraction index is negative and the imaginary part of effective refraction index is approximately zero from 17.6 GHz to 29.0 GHz, meanwhile, the real part of wave impendence is positive within this band. The left-handed characteristic of the left-handed metamaterial is illustrated. Besides, relative left-handed bandwidth is up to 48.9%, far superior to the conventional left-handed metamaterials..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 688 (2013)
Theoretical Study of Structure and Infrared Vibration Spectra about AlBn(n=2~9) Clusters
ZHANG Wei, CHEN Wen-zhou, ZHANG Xiao-dong, and JIANG Zhen-Yi
The geometry structures, stabilities and infrared vibration spectra of AlBn(n=2~9) Clusters were investigated based on density functional theory. The ground state structures of AlB4, AlB5, AlB6 and AlB7 clusters and their relative stabilities were discussed in detail. For the AlBn(n=2~9) ground states, their chemical bThe geometry structures, stabilities and infrared vibration spectra of AlBn(n=2~9) Clusters were investigated based on density functional theory. The ground state structures of AlB4, AlB5, AlB6 and AlB7 clusters and their relative stabilities were discussed in detail. For the AlBn(n=2~9) ground states, their chemical bonds were evaluated by considering the structures, which obtain and loss one electron. The effect of doping Al atom and the revolution of geometry structures were also discussed. It was found that the difference of stabilities becomes smaller after doping Al atom; however, the group of B atoms still plays a dominant role in the whole cluster, especially for the stability; AlB3, AlB5 and AlB8 clusters are local stable among all the clusters studied; for infrared vibration spectra, the modes of vibration, which have higher symmetry and more B atoms involved in, are prior..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 692 (2013)
Application of Stokes Vector Method on the Full-Fiber Current Sensor
HUANG Ai-xian, ZHANG Hao, QIU Yi-shen, WANG Ning, LI Gao-ming, CHEN Shu-ming, and SONG Lei
Considering that the signal analysis is usually based on dual-way intensity detection, a novel method is demonstrated that uses Stokes vector method to analyze the degree of polarization degree in the optical fiber current sensor. In approximate conditions, the reduction transmission matrix is deduced and obtained of tConsidering that the signal analysis is usually based on dual-way intensity detection, a novel method is demonstrated that uses Stokes vector method to analyze the degree of polarization degree in the optical fiber current sensor. In approximate conditions, the reduction transmission matrix is deduced and obtained of the full optical fiber current sensor based on Mueller matrix. It is found that the effect of the Stokes vector method is similar to the Jones vector method; by comparing the Jones vector method with the actual experimental results, it is easy to know that the Stokes vector has more operational advantages, such as only real numbers included in the Mueller matrix, easily being changed to sparse matrix and the final polarization degree being obtained by calculating the second diagonal element of the total transmission matrix. This method can be used in the theoretical analysis of the degree of polarization, and simplify the analysis process and operation process effectively..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 699 (2013)
Effect of Extremely Low Frequency High-voltage Pulsed Electric Field on Ultra-weak Luminescence of Corns during Germination
XI Gang, LIU Kai, YANG Yun-jing, and GAO Yu
Biological ultra-weak luminescence is an electromagnetic signal from cells, which plays an important role in revealing the mechanism of electromagnetic biological effects. In order to study the biological effects and mechanism of extremely low frequency pulsed electric field, 1 Hz extremely low frequency high-voltage pBiological ultra-weak luminescence is an electromagnetic signal from cells, which plays an important role in revealing the mechanism of electromagnetic biological effects. In order to study the biological effects and mechanism of extremely low frequency pulsed electric field, 1 Hz extremely low frequency high-voltage pulsed electric field based on the potential fluctuation frequency of corn cells was used to treat the corns during germination. The results showed that the germination process of corns was accelerated obviously and both the shoot length and root length of germinating corns were significantly longer than the control. Through the measurement and analysis of spontaneous luminescence and delayed luminescence on corns during germination, it was found that the spontaneous luminescence and delayed luminescence integral intensity of germinating corn were significantly increased under the action of 1 Hz extremely low frequency high-voltage pulsed electric field, which indicated that this specific pulsed electric field promoted the DNA synthesis and cell metabolism of the corns during germination. The coupled resonance of pulsed electric field and cell electric field in corn seeds may be the cause of biological effects of the extremely low frequency high-voltage pulsed electric field..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 705 (2013)
Sub-microstructures′ Influences on Cell′s Scattering Prosperities
SUN Du-juan, HU Yi-hua, WANG Yong, LI Le, and LI Lei
A cell model, a cellularstroma model and a “cellularstroma & nuclear” model are presented, which demonstrate three types of biological cells, respectively. By using a FDTD method, models′ RCS in the far-field are compared, and influences of cell′s sub-microstructures, including organelles, nucleolus and cellularstrA cell model, a cellularstroma model and a “cellularstroma & nuclear” model are presented, which demonstrate three types of biological cells, respectively. By using a FDTD method, models′ RCS in the far-field are compared, and influences of cell′s sub-microstructures, including organelles, nucleolus and cellularstroma on its scattering properties are researched. The results show that cells′ scattering properties are mainly determined by cellularstroma. Light scattering from cells and propagating in two directions of 20°≤θ≤40° and 150°≤θ≤180° are increased by nucleus but decreased by organelles, which distribute randomly, that making scattering light intensity in all direction more uniform..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 710 (2013)
Effects of Different Light Intensity and Light Quality on Adventitious Buds Induction and Growth of Clematis‘nelly moser’
XU Ling-ling, DING Duo-duo, TAO Gui-rong, DANG Yue-fang, and GUO Bin
Effects of different light intensity (0, 500, 2 000, 3 000 and 4 000 Lux) and light quality (blue, green and red light) on propagation of axillary buds by Clematis‘nelly moser’ are studied. MS media with NAA (Naphthaleneacetic Acid) 0.2 mg/L+6-BA(6-Benzylaminopurine) 2 mg/L are used as basal media. The experimental resEffects of different light intensity (0, 500, 2 000, 3 000 and 4 000 Lux) and light quality (blue, green and red light) on propagation of axillary buds by Clematis‘nelly moser’ are studied. MS media with NAA (Naphthaleneacetic Acid) 0.2 mg/L+6-BA(6-Benzylaminopurine) 2 mg/L are used as basal media. The experimental results show that the 3 000 Lux white light is better for the axillary buds propagation than the other light quality values. Under 3 000 Lux white light, the adventitious buds per explants, average adventitious bud height per explants and average nodes number are 100%, 4.4, 5.66 cm and 4.6, respectively. Besides, it is found that the blue light significantly enhanced the induction efficiency of adventitious buds, which is 1.27 times than that under white light treatments. The physiological and biochemical data show that the activities of superoxide dismutase (SOD), hydrogen peroxide (CAT), and the ratio of chlorophyll a to b in adventitious bud under blue light treatment are significantly higher than those in the other light quality treatments..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 715 (2013)
Differential Phase Encoding Scheme for the Polarization State of Quantum Signaling and Simulation
[in Chinese], [in Chinese], and [in Chinese]
In order to study the quantum communication signaling system and realize quantum communication between multiple users, a kind of differential phase encoding scheme for the polarization state of quantum signaling is proposed, and details of the encoding process are described. The sender uses polarization states of diffeIn order to study the quantum communication signaling system and realize quantum communication between multiple users, a kind of differential phase encoding scheme for the polarization state of quantum signaling is proposed, and details of the encoding process are described. The sender uses polarization states of different photons to represent different signalings, and then implements phase modulation for the photons and encodes the quantum signaling based on the phase difference between the impulses before and affter encoding. In order to complete the decoding, two optical pulses occur interference at the beam splitter. The signal 0 or 1 can be detected by different detectors according to their phase difference. According to the Gaussian pulse distribution, quantitative relationship amongthe quantum bit error rate caused by the pulse delay to differential phase of encoding system, pulse width and delay time in photonic transmission process are enduced.Besides, quantum bit error rate of single-photon pulsesdistribution of Gaussian is calculated in determined timing jitter. Finally, quantum signaling encoded efficiency and bit error rate are analyzed and simulated.The results show that the encoded efficiency of proposed coding scheme can reach 75% that can satisfy the needs of quantum mobile communication..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 721 (2013)
Quantum Memory with CRIB in an Asymmetric Optical Cavity
GAO Wei, WANG Ming-feng, and ZHENG Yi-zhuang
We propose an efficient quantum memory scheme with controlled reversible inhomogeneous broadening in an optical cavity. When the absorption per cavity round trip exactly matches the transmission of the coupling mirror (impedance matching condition), we show that the input light field can be completely absorbed by an inWe propose an efficient quantum memory scheme with controlled reversible inhomogeneous broadening in an optical cavity. When the absorption per cavity round trip exactly matches the transmission of the coupling mirror (impedance matching condition), we show that the input light field can be completely absorbed by an inhomogeneous broadening atomic ensemble. From calculation we obtain that either a forward or a backward retrieval process the quantum memory efficiency can reach unity even for a small optical depth of the atomic system. If there is no cavity, 100% efficiency is obtained only for extremely large optical depth. A high efficiency for the quantum memory at a small optical depth is easily achieved in practice. Therefore our proposal offers promising possibilities for the practical realization of high quantum memory efficiency..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 727 (2013)
Second Order Total Generalized Variation for Image Zooming
WU Yu-lian, FENG Xiang-chu, and JIANG Dong-huan
To obtain higher resolution images, a new model for image zooming based on total generalized variation is proposed. Original low-resolution image is regarded as sub-space projection of zoomed image to its own space, and the final zoomed image is obtained by application of second order total generalized variation regulaTo obtain higher resolution images, a new model for image zooming based on total generalized variation is proposed. Original low-resolution image is regarded as sub-space projection of zoomed image to its own space, and the final zoomed image is obtained by application of second order total generalized variation regularization. By analyzing the properties of the new model, an efficient primal-dual algorithm is introduced. Experimental results suggest that the proposed algorithm can remove block effect and keep more details, so the high quality image is reconstructed; the model is better than the total variation mode and the wavelet model in terms of both peak signal to noise ratio and root mean square error..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 732 (2013)
A Fast Calibration Method of Camera Response Function for High Dynamic Range Image
FANG Hua-meng, YI Ben-shun, GAN Liang-cai, WEN Chuang, and HUANG Tai-qi
A fast and effective method is presented to solve the problem of inefficiency in calibration algorithm for camera response function in synthesis of high dynamic range image. Firstly, according to the fact that the corresponding illuminances on scenes in imaging process among multi-exposure images are accordant, a new lA fast and effective method is presented to solve the problem of inefficiency in calibration algorithm for camera response function in synthesis of high dynamic range image. Firstly, according to the fact that the corresponding illuminances on scenes in imaging process among multi-exposure images are accordant, a new least-squares error function is proposed to reduce the dimensions of calibration equation. Gaussian weight function is used in accordance with noise distribution of images in different exposures to eliminate ambient noise in image process in excessive dark and light area with high efficiency to solve equations. Meanwhile, robust QR decomposition is put forward to accelerate the calculation of camera response function. At last, the look-up table method is adopted and Gaussian weight function is used to synthetize the illuminances on scences and tone mapping; the result image can be well expressed to obtained the detail information of dark and light area in entire scene. The sufficient experimental results on various scenes indicate that this method has smaller computational amount, higher speed than traditional method and has good precision as well. The proposed method can be used to accomplish rapid calibration of camera response function while subjective effect is good in the visualization image obtained by this method. And this method can be applied widely in portable camera equipments..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 737 (2013)
Auto-exposure Algorithm for Scenes with High Dynamic Range Based on Image Entropy
YANG Zuo-ting, RUAN Ping, and ZHAI Bo
Automatic exposure control is a process of optimizing image brightness by controlling the exposure. To achieve auto exposure in digital cameras, image brightness is widely used because of its direct relationship with exposure value. Although entropy has been used in various image processing applications, it has not beeAutomatic exposure control is a process of optimizing image brightness by controlling the exposure. To achieve auto exposure in digital cameras, image brightness is widely used because of its direct relationship with exposure value. Although entropy has been used in various image processing applications, it has not been used for AE application. A new auto-exposure algorithm was proposed based on the image entropy. The proposed method calculated the entropy of captured images to estimate lighting conditions. By comparing the image entropy and entropy threshold, the images were divided into the regions of interest and regions of no interest. After that, assign different weights to the regions of interest and regions of no interest, so that the overall brightness level was made to carry more information of the regions of interest. At last, the image can get accurate automatic exposure. The algorithm is mainly based on the image entropy, so the exposures are not affected by the location of objects in the image. It can make the algorithm more flexible. The experiment results show that the algorithm can accurately detect high-contrast lighting conditions and improve the dynamic range of output images for a camera system, at the same time the algorithm can also increases the accuracy of auto exposure..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 742 (2013)
Application of Near Infrared Techniques in Paper Moisture Parameter Measurement
YU Dian-hong, LI Lin, and ZHAO Kai
In order to solve the online inspection problem of paper moisture rate technical specification, the moisture rate measuring technique based on the near infrared spectroscopic analysis is researched. The basic theory on the spectral absorption of medium is expatiated and the problems applying the theory to the moisture In order to solve the online inspection problem of paper moisture rate technical specification, the moisture rate measuring technique based on the near infrared spectroscopic analysis is researched. The basic theory on the spectral absorption of medium is expatiated and the problems applying the theory to the moisture rate measurement are also analyzed. The key technique that can realize the moisture rate on-line inspection by means of two near infrared spectral lines (measuring spectral line and the reference line) is explored in detail. The measurement project is designed and the role of the main functional module in the project is discussed. The corresponding experimental research showed that, the precision of moisture rate measurement based on near infrared spectroscopic method is less than0.5%. It is higher than measuring precision of the dry method and the method can be applied to on-line inspection in paper-making process..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 747 (2013)
A Method of Automatic Surface Mounted Device Resistor Defect Detection
HE Ping, WEN Ji-quan, and ZHAO Ming-xuan
Simple structure, orderliness and few gray level of SMD (surface mounted device) resistor image are the prominent feature of SMD resistor units array, through binary resistor image, edge detection, line detection, with the correlation coefficient as a criterion for defects. A method for resistor flaw detection was propSimple structure, orderliness and few gray level of SMD (surface mounted device) resistor image are the prominent feature of SMD resistor units array, through binary resistor image, edge detection, line detection, with the correlation coefficient as a criterion for defects. A method for resistor flaw detection was proposed based on subgraph projection matching. The feature of resistor flaw was extracted on basis of the method of PCA (principal component analysis). Then the resistor flaw would be classified by SVM (support vector machine). At last, an experimental platform was built and the result verifies that the detection rate employed the proposed method is 92.5%, and the method meets the requirements on high accuracy and speed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 42, Issue 6, 751 (2013)
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