Journals >Chinese Optics Letters
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2011
Volume: 9 Issue 5
25 Article(s)
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Atomic and Molecular Physics
Application of electric field ionization method to detect the high-lying Rydberg states of Eu I
Jun Xie, Chang jian Dai, and Ming Li
The 4f7 6s(9S)np 8PJ (J=5/2, 7/2, 9/2) Rydberg series converging to the first ionization limit 4f7 6s 9S4 of the Eu atom using the three-step laser excitation and electric-field-ionization (EFI) method are studied. First, the Eu atom is excited from the 4f7 6s2 8So7/2 ground state to the 4f76s7s 8So7/2 state through thThe 4f7 6s(9S)np 8PJ (J=5/2, 7/2, 9/2) Rydberg series converging to the first ionization limit 4f7 6s 9S4 of the Eu atom using the three-step laser excitation and electric-field-ionization (EFI) method are studied. First, the Eu atom is excited from the 4f7 6s2 8So7/2 ground state to the 4f76s7s 8So7/2 state through the 4f7 6s6p 10P9/2 state by the first two dye lasers. Next, it is populated to many higher-n members of the 4f7 6s(9S)np 8PJ Rydberg series by the third dye laser whose wavelength is scanned within a certain range. Finally, the atom in these higher-n states is ionized by the external pulsed electric field. With the field strength up to 2 kV/cm, we can detect the atom in 4f76s(9S)np 8PJ states with n>40. With the given laser line width, the level energies of Rydberg states with n as high as 72 can be determined. We not only confirm the previous data on the 4f76s(9S) np 8PJ Rydberg series, but also extend the n-value assignment significantly by detecting more states..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050201 (2011)
Instrumentation, Measurement, and Metrology
Novel temperature modeling and compensation method for bias of ring laser gyroscope based on least-squares support vector machine
Xudong Yu, Yu Wang, Guo Wei, Pengfei Zhang, and Xingwu Long
Bias of ring-laser-gyroscope (RLG) changes with temperature in a nonlinear way. This is an important restraining factor for improving the accuracy of RLG. Considering the limitations of least-squares regression and neural network, we propose a new method of temperature compensation of RLG bias-building function regressBias of ring-laser-gyroscope (RLG) changes with temperature in a nonlinear way. This is an important restraining factor for improving the accuracy of RLG. Considering the limitations of least-squares regression and neural network, we propose a new method of temperature compensation of RLG bias-building function regression model using least-squares support vector machine (LS-SVM). Static and dynamic temperature experiments of RLG bias are carried out to validate the effectiveness of the proposed method. Moreover, the traditional least-squares regression method is compared with the LS-SVM-based method. The results show the maximum error of RLG bias drops by almost two orders of magnitude after static temperature compensation, while bias stability of RLG improves by one order of magnitude after dynamic temperature compensation. Thus, the proposed method reduces the influence of temperature variation on the bias of the RLG effectively and improves the accuracy of the gyro scope considerably..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051201 (2011)
Instantaneous frequency measurement based on transversal microwave filters with high resolution
Jianji Dong, Yuan Yu, Xinliang Zhang, and Dexiu Huang
We propose a novel photonic technique for microwave frequency measurement based on transversal microwave filters with high resolution. Two parallel microwave filters with sine and cosine frequency responses are obtained by cross gain modulation in a single semiconductor optical amplifier, which introduces two differentWe propose a novel photonic technique for microwave frequency measurement based on transversal microwave filters with high resolution. Two parallel microwave filters with sine and cosine frequency responses are obtained by cross gain modulation in a single semiconductor optical amplifier, which introduces two different frequency responses to achieve an amplitude comparison function. We also demonstrate a proof-of-concept experiment. The measurement error is less than +-0.04 GHz for the first band range of 0-3.45 GHz and less than +-0.03 GHz for the second band range of 3.45-5.8 GHz. Our scheme is found to be capable of being extended for larger frequency range measurements using a shorter fiber length..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051202 (2011)
Lasers and Laser Optics
Low power penalty tunable slow light using vertical-cavity surface-emitting laser amplifier
Yanan Ma, Bin Luo, Lianshan Yan, Wei Pan, Xihua Zou, Jia Ye, Anlin Yi, and Di Zheng
A tunable slow light of 2.5-Gb/s pseudo-random binary sequence signal using a 1550-nm vertical-cavity surface-emitting laser (VCSEL) is experimentally demonstrated. The influences of the bias current and the gain saturation on the slow light are investigated. With bias current increasing, tunable optical group delay upA tunable slow light of 2.5-Gb/s pseudo-random binary sequence signal using a 1550-nm vertical-cavity surface-emitting laser (VCSEL) is experimentally demonstrated. The influences of the bias current and the gain saturation on the slow light are investigated. With bias current increasing, tunable optical group delay up to 98 ps is obtained at room temperature. Demonstration of the time delay between 16 and 24 ps by signal intensity change is reported. Under an appropriate bias current, by tuning the input signal to track the peak gain wavelength of the VCSEL, slow light of a power penalty as low as 1 dB is achieved. With such a low power penalty, the VCSEL has a great potential application as a compact optical buffer..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051401 (2011)
Deformation behavior of laser bending of circular sheet metal
Q. Nadeem, and S. J. Na
The application of a thermal source in non-contact forming of sheet metal has long been used. However, the replacement of this thermal source with a laser beam promises much greater controllability of the process. This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and maThe application of a thermal source in non-contact forming of sheet metal has long been used. However, the replacement of this thermal source with a laser beam promises much greater controllability of the process. This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components. Forming is made possible through laser-induced non-uniform thermal stresses. In this letter, we use the geometrical transition from rectangular to circle-shaped specimen and ring-shaped specimen to observe the effect of geometry on deformation in laser forming. We conduct a series of experiments on a wide range of specimen geometries. The reasons for this behavior are also analyzed. Experimental results are compared with simulated values using the software ABAQUS. The utilization of line energy is found to be higher in the case of laser forming along linear irradiation than along curved ones. We also analyze the effect of strain hindrance. The findings of the study may be useful for the inverse problem, which involves acquiring the process parameters for a known target shape of a wide range of complex shape geometries..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051402 (2011)
Microstructure evolution of laser solid forming of Ti-Al-V ternary system alloys from blended elemental powders
Hua Tan, Fengying Zhang, Jing Chen, Xin Lin, and Weidong Huang
Morphology evolution of prior \beta grains of laser solid forming (LSF) Ti-xAl-yV (x \leq 11,y \leq 20) alloys from blended elemental powders is investigated. The formation mechanism of grain morphology is revealed by incorporating columnar to equiaxed transition (CET) mechanism during solidification. The morphology ofMorphology evolution of prior \beta grains of laser solid forming (LSF) Ti-xAl-yV (x \leq 11,y \leq 20) alloys from blended elemental powders is investigated. The formation mechanism of grain morphology is revealed by incorporating columnar to equiaxed transition (CET) mechanism during solidification. The morphology of prior \beta grains of LSF Ti-6Al-yV changes from columnar to equiaxed grains with increasing element V content from 4 to 20 wt.-%. This agrees well with CET theoretical prediction. Likewise, the grain morphology of LSF Ti-xAl-2V from blended elemental powders changes from large columnar to small equiaxed with increasing Al content from 2 to 11 wt.-%. The macro-morphologies of LSF Ti-8Al-2V and Ti-11Al-2V from blended elemental powders do not agree with CET predictions. This is caused by the increased disturbance effects of mixing enthalpy with increasing Al content, generated in the alloying process of Ti, Al, and V in the molten pool..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051403 (2011)
Optical Devices
Guided modes in asymmetric metal-cladding left-handed material waveguides
Ying He, Xia Zhang, Yanfang Yang, and Chunfang Li
We investigate guided modes in the asymmetric waveguide structure with a left-handed material (LHM) layer surrounded by air and metal. A graphical method is proposed to determine the guided modes. New properties of the oscillating and surface guided modes, such as absence of the fundamental mode, coexistence of the oscWe investigate guided modes in the asymmetric waveguide structure with a left-handed material (LHM) layer surrounded by air and metal. A graphical method is proposed to determine the guided modes. New properties of the oscillating and surface guided modes, such as absence of the fundamental mode, coexistence of the oscillating and surface guided modes, fast attenuation of the surface guided modes, and mode degeneracy, are analyzed in detail. We also investigate dispersive characteristics of the metal-LHM-air optical waveguide. The propagation constant increases with decreasing slab thickness for the first-order oscillating mode, which is different from that in traditional metal-cladding waveguides..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 052301 (2011)
Influencing factors of microscanning performance based on flat optical component
Xiubao Sui, Lianfa Bai, Qian Chen, and Guohua Gu
To decrease the performance difference between the actual microscanning thermal imager and the theoretical value, a germanium lens (placed at a certain angle between the infrared focal plane array and infrared lens) dip angle model of flat optical component microscanning is introduced in this letter. The model is the bTo decrease the performance difference between the actual microscanning thermal imager and the theoretical value, a germanium lens (placed at a certain angle between the infrared focal plane array and infrared lens) dip angle model of flat optical component microscanning is introduced in this letter. The model is the basis for choosing the dip angle of the germanium lens, which is used in the microscanning thermal imager. In addition, the actual dip angle of the germanium lens is chosen according to the model, the infrared lens parameters of the thermal imager, and the germanium lens parameters of manufacture and installation. Only in this manner can the optimal performance of the microscanning thermal imager based on the flat optical component be obtained. Results of the experiments confirm the accuracy of the conclusions above..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 052302 (2011)
Fiber Optics and Optical Communications
Experiment on 60-GHz MMW transmission performance in an optical fiber and wireless system
Qi Tang, Lin Chen, Jiangnan Xiao, and Zizheng Cao
We experimentally investigate the transmission performance of 60-GHz signals over standard single-mode fiber (SSMF) and wireless links at different bit rates. Experimental results show that in a transmission of over 10-km SSMF and 1.3-m wireless link, bit rate reaches up to 5 Gb/s and bit error rate (BER) is less than We experimentally investigate the transmission performance of 60-GHz signals over standard single-mode fiber (SSMF) and wireless links at different bit rates. Experimental results show that in a transmission of over 10-km SSMF and 1.3-m wireless link, bit rate reaches up to 5 Gb/s and bit error rate (BER) is less than 10^{-4}. The main limiting factor in such radio-over-fiber (ROF) systems is intersymbol interferences caused by the so-called walk-off effect when BER is below 10^{-8}. In addition, a transmission of over 20-km SSMF without chromatic dispersion compensation is brie°y investigated. For a BER of 10?8, the optical penalty is 2 dB..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050601 (2011)
Fiber-optic Fabry Perot strain sensor based on graded-index multimode fiber
Tian Zhao, Yuan Gong, Yunjiang Rao, Yu Wu, Zengling Ran, and Huijuan Wu
By using a graded-index multimode fiber (GI-MMF) with a relatively flat index profile and high refractive index of the fiber core, a microextrinsic fiber-optic Fabry?P′erot interferometric (MEFPI) strain sensor is fabricated through chemical etching and fusion splicing. Higher reflectance of the microcavity is obtainedBy using a graded-index multimode fiber (GI-MMF) with a relatively flat index profile and high refractive index of the fiber core, a microextrinsic fiber-optic Fabry?P′erot interferometric (MEFPI) strain sensor is fabricated through chemical etching and fusion splicing. Higher reflectance of the microcavity is obtained due to the less-curved inner wall in the center of the fiber core after etching and higher index contrast between the GI-MMF core and air. The maximum reflection of the sensor is enhanced 12 dB than that obtained by etching of the Er- or B-doped fibers. High fringe contrast of 22 dB is obtained. The strain and temperature responses of the MEFPI sensors are investigated in this experiment. Good linearity and high sensitivity are achieved, with wavelength-strain and wavelength-temperature sensitivities of 7.82 pm/\mu \varepsilon and 5.01 pm/?C, respectively..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050602 (2011)
Design procedure for photonic crystal fibers with ultra-flattened chromatic dispersion
Huizhen Xu, Jian Wu, Yitang Dai, Cong Xu, and Jintong Lin
A simple design procedure is used to generate photonic crystal fibers (PCFs) with ultra-flattened chromatic dispersion. Only four parameters are required, which not only considerably saves the computing time, but also distinctly reduces the air-hole quantity. The influence of the air-hole diameters of each ring of hexaA simple design procedure is used to generate photonic crystal fibers (PCFs) with ultra-flattened chromatic dispersion. Only four parameters are required, which not only considerably saves the computing time, but also distinctly reduces the air-hole quantity. The influence of the air-hole diameters of each ring of hexagonal PCFs (H-PCF, including 1-hole-missing and 7-hole-missing H-PCFs), circular PCFs (C-PCF), square PCFs (S-PCF), and octagonal PCFs (O-PCF) is investigated through simulations. Results show that regardless of the cross section structures of the PCFs, the 1st ring air-hole diameter has the greatest influence on the dispersion curve followed by that of the 2nd ring. The 3rd ring diameter only affects the dispersion curve within longer wavelengths, whereas the 4th and 5th rings have almost no influence on the dispersion curve. The hole-to-hole pitch between rings changes the dispersion curve as a whole. Based on the simulation results, a procedure is proposed to design PCFs with ultra-flattened dispersion. Through the adjustment of air-hole diameters of the inner three rings and hole-to-hole pitch, a flattened dispersion of 0+-0.5 ps/(nm.km) within a wavelength range of 1.239–2.083 \mum for 5-ring 1-hole-missing H-PCF, 1.248–1.992 \mum for 5-ring C-PCF, 1.237–2.21 \mum for 5-ring S-PCF, 1.149–1.926 \mum for 5-ring O-PCF, and 1.294–1.663 \mum for 7-hole-missing H-PCF is achieved..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050603 (2011)
Highly efficient fiber-to-chip evanescent coupling based on subwavelength-diameter optical fibers
Xiaowei Shen, Xinwan Li, Linjie Zhou, Zehua Hong, Xiaocao Yu, Ying Zhang, and Jianping Chen
A novel, compact, and highly efficient fiber-to-chip evanescent coupling structure is proposed based on a subwavelength-diameter fiber. The coupling structure is characterized by a large misalignment tolerance and easy fabrication. The dependence of coupling efficiency on various parameters is calculated and analyzed. A novel, compact, and highly efficient fiber-to-chip evanescent coupling structure is proposed based on a subwavelength-diameter fiber. The coupling structure is characterized by a large misalignment tolerance and easy fabrication. The dependence of coupling efficiency on various parameters is calculated and analyzed. The simulation results show that a coupling efficiency as high as 95% can be obtained within a coupling length of <4 \mum..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050604 (2011)
OSNR-aware lightpath provisioning in distributed optical network
Huifeng Bai, and Yuefeng Ji
An optical signal-to-noise ratio (OSNR) aware lightpath provisioning mechanism (OSNR-LPM) is proposed for distributed optical networks. This OSNR-LPM takes the OSNR value of the lightwave along the lightpath into consideration when establishing the lightpath for the connection request using resource reservation protocoAn optical signal-to-noise ratio (OSNR) aware lightpath provisioning mechanism (OSNR-LPM) is proposed for distributed optical networks. This OSNR-LPM takes the OSNR value of the lightwave along the lightpath into consideration when establishing the lightpath for the connection request using resource reservation protocol-traffic engineering (RSVP-TE). Moreover, the OSNR-LPM makes full advantages of the OSNR monitoring function in each node and assigns the lightwave by judging the OSNR value carried by the signaling message in order to guarantee the reliable establishment of the lightpath in the data plane.The simulation results show that the OSNR-LPM outperforms other lightpath assignment mechanisms in terms of real blocking probability in the data plane..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050605 (2011)
Thin Films
Accurate analysis of ellipsometric data for thick transparent f ilms
Yuan Zhao, Mingyu Sheng, Yuxiang Zheng, and Liangyao Chen
Using e-beam evaporation, the ellipsometric parameters of thick transparent films are studied with the modified analysis method for the SiO2 film samples deposited onto the Si substrate. The ellipsometric parameters are measured at the incidence angles changing from 50? to 70? and in the 3–4.5 eV photon energy range. TUsing e-beam evaporation, the ellipsometric parameters of thick transparent films are studied with the modified analysis method for the SiO2 film samples deposited onto the Si substrate. The ellipsometric parameters are measured at the incidence angles changing from 50? to 70? and in the 3–4.5 eV photon energy range. The error in the conventional method can be significantly reduced by the modified ellipsometric method considering the spatial effect to show good agreement between the theoretical and experimental results. The new method presented in this letter can be applied to other optical measurement of the periodic or non-periodic film structures..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 053101 (2011)
Spectroscopic ellipsometric properties and resistance switching behavior in Six(ZrO2)100x films
Xiaodong Wang, Liang Feng, Shenjin Wei, Huanfeng Zhu, Kun Chen, Da Xu, Ying Zhang, and Jing Li
We prepare Six(ZrO2)100?x composite films using the co-sputtering method. The chemical structures of the films which are prepared under different conditions are analyzed with X-ray photoemission spectroscopy. Thermal treatment influences on optical property and resistance switching characteristics of these composite fiWe prepare Six(ZrO2)100?x composite films using the co-sputtering method. The chemical structures of the films which are prepared under different conditions are analyzed with X-ray photoemission spectroscopy. Thermal treatment influences on optical property and resistance switching characteristics of these composite films are investigated by spectroscopic ellipsometry and semiconductor parameter analyzer, respectively. With the proper Si-doped Six(ZrO2)100?x interlayer, the Al/ Six(ZrO2)100?x/Al device cell samples present very reliable and reproducible switching behaviors. It provides a feasible solution for easy multilevel storage and better fault tolerance in nonvolatile memory application..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 053102 (2011)
Nonlinear Optics
Efficient two-photon sensitized luminescence of europium (III) complex based on hypersensitive transitions
Meng Shi, Hua Li, Mei Pan, Fufang Su, Lili Ma, Peigao Han, and Hezhou Wang
Red frequency-upconversion fluorescence emission is observed in europium (III) complex with encapsulating polybenzimidazole tripodal ligands, pumped with 930- and 1070-nm picosecond laser pulses. The luminescence of transition 5D0->7F2 (612 nm) is induced by two-photon absorption of hypersensitive transitions 7F0-&gRed frequency-upconversion fluorescence emission is observed in europium (III) complex with encapsulating polybenzimidazole tripodal ligands, pumped with 930- and 1070-nm picosecond laser pulses. The luminescence of transition 5D0->7F2 (612 nm) is induced by two-photon absorption of hypersensitive transitions 7F0->5D2 (465 nm) and 7F1->5D1 (535 nm). Analysis results suggest that the two-photon excitation strength of these hypersensitive transitions is increased dramatically owing to the C3 symmetry of the coordination field..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051901 (2011)
Terahertz-wave generation by surface-emitted four-wave mixing in optical fiber
Ping Zhou, and Dianyuan Fan
We propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-waveWe propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-wave power expression is presented using the coupled-wave theory. This is a promising way for realizing a reasonable narrow-band terahertz-wave source..
Chinese Optics Letters
- Publication Date: Apr. 18, 2011
- Vol. 9, Issue 5, 051902 (2011)
Femtosecond pulses cleaning by transient-grating process in Kerr-optical media
Jun Liu, Kotaro Okamura, Yuichiro Kida, and Takayoshi Kobayashi
We use a transient-grating (TG) process in a Kerr bulk medium to clean a femtosecond laser pulse. Using the technique, the temporal contrast of the generated TG signal is improved by more than two orders of magnitude in comparison with the incident pulse in a 0.5-mm-thick fused silica plate. The laser spectrum is smootWe use a transient-grating (TG) process in a Kerr bulk medium to clean a femtosecond laser pulse. Using the technique, the temporal contrast of the generated TG signal is improved by more than two orders of magnitude in comparison with the incident pulse in a 0.5-mm-thick fused silica plate. The laser spectrum is smoothed and broadened, and the pulse duration is shortened simultaneously. We expect to extend this technique to a clean pulse with broadband spectral bandwidth at a wide spectral range because it is a phase-matched process..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051903 (2011)
Optical Design and Fabrication
Optical design for EUV lithography source collector
Shuqing Zhang, Qi Wang, Dongyuan Zhu, Runshun Li, and Chang Liu
Wolter I collector is the best collector for extreme ultraviolet (EUV) lithography, which has a series of nested mirrors. It has high collection efficiency and can obtain more uniform intensity distribution at the intermediate focus (IF). A new design with the calculation sequence from the outer mirror to the inner oneWolter I collector is the best collector for extreme ultraviolet (EUV) lithography, which has a series of nested mirrors. It has high collection efficiency and can obtain more uniform intensity distribution at the intermediate focus (IF). A new design with the calculation sequence from the outer mirror to the inner one on the premise of satisfying the requirements of the collector is introduced. Based on this concept, a computer program is established and the optical parameters of the collector using the program is calculated. The design results indicate that the collector satisfies all the requirements..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 052201 (2011)
Image Processing
Improved multilevel filters to enhance infrared small target
Xiaoping Wang, Tianxu Zhang, Luxin Yan, Man Wang, and Jiawei Wu
We propose improved multilevel filters (IMLFs) involving the absolute value operation into the algorithmic framework of traditional multilevel filters (MLFs) to improve the robustness of infrared small target enhancement techniques under a complex infrared cluttered background. Compared with the widely used small targeWe propose improved multilevel filters (IMLFs) involving the absolute value operation into the algorithmic framework of traditional multilevel filters (MLFs) to improve the robustness of infrared small target enhancement techniques under a complex infrared cluttered background. Compared with the widely used small target enhancement methods which only deal with bright targets, the proposed technique can enhance the infrared small target, whether it is bright or dark. Experimental results verify that the proposed technique is efficient and practical..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051001 (2011)
Parallel sub-neural network system for hand vein pattern recognition
Xue Yuan, Yongduan Song, and Xueye Wei
A hand vein authentication system in which the identity of an individual can be readily confirmed upon gripping a handle is proposed. This recognition method incorporates infrared light-emitting diode (LED) onto a door handle and sets a charge-coupled device (CCD) camera on the other side of the hand. It builds on fuzzA hand vein authentication system in which the identity of an individual can be readily confirmed upon gripping a handle is proposed. This recognition method incorporates infrared light-emitting diode (LED) onto a door handle and sets a charge-coupled device (CCD) camera on the other side of the hand. It builds on fuzzy c-means clustering and parallel neural networks (NNs); moreover, it is expected to solve the pattern recognition problem in large-scale databases using NNs due to its self-learning and parallel processing capabilities and by effectively incorporating training patterns. The experimental results validate the e±ciency of the proposed algorithm..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051002 (2011)
Minimum mean square error method for stripe nonuniformity correction
Weixian Qian, Qian Chen, and Guohua Gu
Stripe nonuniformity is very typical in line infrared focal plane (IRFPA) and uncooled starring IRFPA. We develop the minimum mean square error (MMSE) method for stripe nonuniformity correction (NUC). The goal of the MMSE method is to determine the optimal NUC parameters for making the corrected image the closest to thStripe nonuniformity is very typical in line infrared focal plane (IRFPA) and uncooled starring IRFPA. We develop the minimum mean square error (MMSE) method for stripe nonuniformity correction (NUC). The goal of the MMSE method is to determine the optimal NUC parameters for making the corrected image the closest to the ideal image. Moreover, this method can be achieved in one frame, making it more competitive than other scene-based NUC algorithms. We also demonstrate the calibration results of our algorithm using real and virtual infrared image sequences. The experiments verify the positive effect of our algorithm..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 051003 (2011)
Vision, Color, and Visual Optics
Investigation of unique hue setting changes with ageing
Chenyang Fu, Kaida Xiao, Dimosthenis Karatzas, and Sophie Wuerger
Clromatic sensitivity along the protan, deutan, and tritan lines and the loci of the unique hues (red, green, yellow, blue) for a very large sample (n = 185) of colour-normal observers ranging from 18 to 75 years of age are assessed. Visual judgments are obtained under normal viewing conditions using colour patches on Clromatic sensitivity along the protan, deutan, and tritan lines and the loci of the unique hues (red, green, yellow, blue) for a very large sample (n = 185) of colour-normal observers ranging from 18 to 75 years of age are assessed. Visual judgments are obtained under normal viewing conditions using colour patches on self-luminous display under controlled adaptation conditions. Trivector discrimination thresholds show an increase as a function of age along the protan, deutan, and tritan axes, with the largest increase present along the tritan line, less pronounced shifts in unique hue settings are also observed. Based on the chromatic (protan, deutan, tritan) thresholds and using scaled cone signals, we predict the unique hue changes with ageing. A dependency on age for unique red and unique yellow for predicted hue angle is found. We conclude that the chromatic sensitivity deteriorates significantly with age, whereas the appearance of unique hues is much less affected, remaining almost constant despite the known changes in the ocular media..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 053301 (2011)
Atmospheric and Oceanic Optics
Comparison of simultaneous signals obtained from a dual-field-of-view lidar and its application to noise reduction based on empirical mode decomposition
Wei Gong, Jun Li, Feiyue Mao, and Jinye Zhang
Although the empirical mode decomposition (EMD) method is an effective tool for noise reduction in lidar signals, evaluating the effectiveness of the denoising method is difficult. A dual-field-of-view lidar for observing atmospheric aerosols is described. The backscattering signals obtained from two channels have diffAlthough the empirical mode decomposition (EMD) method is an effective tool for noise reduction in lidar signals, evaluating the effectiveness of the denoising method is difficult. A dual-field-of-view lidar for observing atmospheric aerosols is described. The backscattering signals obtained from two channels have different signal-to-noise ratios (SNRs). The performance of noise reduction can be investigated by comparing the high SNR signal and the denoised low SNR signal without a simulation experiment. With this approach, the signal and noise are extracted to one intrinsic mode function (IMF) by the EMD-based denoising; thus, the threshold method is applied to the IMFs. Experimental results show that the improved threshold method can effectively perform noise reduction while preserving useful sudden-change information..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 050101 (2011)
Optoelectronics
Ultraviolet photodetector with bandpass characteristic based on a blend of PVK and PBD
Jian Sun, Kuanjun Peng, Lu Zhu, Zuofu Hu, Qian Dai, Xiqing Zhang, and Yongsheng Wang
We fabricate an ultraviolet photodetector based on a blend of poly (N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3, 4-oxadiazole (PBD) using spin coating. The device exhibites a low dark current density of 2.2 \times 10?3 \muA/cm2 at zero bias. The spectral response of the device shows a narrow bandpass We fabricate an ultraviolet photodetector based on a blend of poly (N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3, 4-oxadiazole (PBD) using spin coating. The device exhibites a low dark current density of 2.2 \times 10?3 \muA/cm2 at zero bias. The spectral response of the device shows a narrow bandpass characteristic from 300 to 355 nm, and the peak response is 18.6 mA/W located at 334 nm with a bias of –1 V. We also study the performances of photodetectors with different blend layer thicknesses. The largest photocurrent density is obtained with a blend of 90 nm at the same voltage..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 5, 052501 (2011)
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