Journals >Acta Photonica Sinica
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2020
Volume: 49 Issue 9
21 Article(s)
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Influence of Strain on Performance of Independent Emitters in High Power Quasi-continuous Semiconductor Laser Array
Bo LI, Zhen-fu WANG, Bo-cang QIU, Guo-wen YANG, Te LI, Yu-liang ZHAO, Yu-xian LIU, Gang WANG, and Shao-bo BAI
In order to study the issues of non-uniform performance of the emitters in laser bars, 960 nm laser bars with 38 emitters and cavity length of 2 mm packaged by the microchannel cooler were experimentally studied. The peak output power reaches 665.6 W, the electro-optic conversion efficiency is 63.8%, and the centroid wIn order to study the issues of non-uniform performance of the emitters in laser bars, 960 nm laser bars with 38 emitters and cavity length of 2 mm packaged by the microchannel cooler were experimentally studied. The peak output power reaches 665.6 W, the electro-optic conversion efficiency is 63.8%, and the centroid wavelength is 959.5 nm under the driving current of 600 A and the duty ratio of 10%. Firstly, theoretical analysis was made to find out the relationship between the external stress and laser''s parameter changes. Then, the laser photoelectric characteristics parameters such as threshold current, slope efficiency, spectrum and optical power were measured via the test setup. From external stress theory, it is clear that external stress can significantly affect the laser''s parameter performance. Specifically, compressive strain will cause blue-shift in wavelength, decrease in threshold current, and increase in laser and slope efficiency; tensile strain by contrast, will have completely opposite effects on the laser performance. Studies have shown the performance that affects the internal emitters is not only thermal effects, but also residual strain after packaging. The distribution of stress can basically predict the pattern of array performance, which will provide a reference for the development of high peak power, high reliability semiconductor laser arrays..
Acta Photonica Sinica
- Publication Date: Dec. 23, 2020
- Vol. 49, Issue 9, 914001 (2020)
Atmospheric and Oceanic Optics
Real-time Correction Method of Air Phase Disturbance of Antenna Array Based on GNSS Difference
Xi-ping XUE, Chun-lai LI, Hong-bo ZHANG, De-qing KONG, Liang DONG, Yan SU, Xin-ying ZHU, Shun DAI, Jun-duo LI, Chen LI, Yu-xiang WU, and Zan WANG
A real-time correction method based on Global Navigation Satellite System difference is proposed for the atmospheric phase disturbance of the antenna array. The atomic clock with high stability is used as the external frequency standard, the single difference of the carrier phase and the double difference on the epoch A real-time correction method based on Global Navigation Satellite System difference is proposed for the atmospheric phase disturbance of the antenna array. The atomic clock with high stability is used as the external frequency standard, the single difference of the carrier phase and the double difference on the epoch between the two stations are utilized, and the phase change caused by the satellite movement is deducted through the ephemeris. After the cycle slip detection and correction, the satellite orbit and the coordinate error of the station are eliminated through the long period fitting. Finally, the real-time measurement of ionospheric and tropospheric disturbances in two places is realized by dual frequency or multi frequency signals. A set of Global Navigation Satellite System receiving equipment was deployed at Miyun Observing Station and Kunming Observing Station of the National Astronomical Observatory of the Chinese Academy of Sciences, to verify the real-time correction method of atmospheric phase disturbance. The results show that the root-mean-square of the corrected atmospheric phase disturbance reaches 1.9 mm, modified by using the dual frequency carrier phase, under different weather conditions. The results indicate that the method can be used for the correction of the atmospheric phase disturbance of the antenna array in radio astronomy and deep space exploration..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0901001 (2020)
Imaging Analysis of Reflective Ghost Imaging in Oceanic Turbulence
Qin-wei ZHANG, Lian-zhen CAO, Xia LIU, Yang YANG, Jia-qiang ZHAO, Huai-xin LU, and Zhi-bo HE
Based on the extended Huygens-Fresnel integral and the theory of ghost imaging, the reflective lensless ghost imaging through Kolmogorov oceanic turbulence is investigated. The theoretical expressions for the impulse response function and the visibility of reflective ghost imaging in oceanic turbulence are obtained. ThBased on the extended Huygens-Fresnel integral and the theory of ghost imaging, the reflective lensless ghost imaging through Kolmogorov oceanic turbulence is investigated. The theoretical expressions for the impulse response function and the visibility of reflective ghost imaging in oceanic turbulence are obtained. The results show that the quality of reflective ghost imaging could be maintained at a relatively small incident reflective angle, whereas the quality is degraded dramatically at a relatively long distance with a relatively big incident reflective angle. The visibility of reflective ghost imaging is analyzed under various turbulence conditions and over different propagation distances by numerical calculation. It is a guidance for the realization of adaptive underwater optical ghost imaging over different length scales under the effect of oceanic turbulence..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0901002 (2020)
Fiber Optics and Optical Communications
Coupling Efficiency of Light Intensity from Blackbody Cavity into Spherical Optical Fiber
Chao-xin SONG, Xiao-hua LEI, Lei XIE, Xian-ming LIU, and Wei-min CHEN
To improve coupling efficiency from blackbody source into fiber, a coupling model of light intensity from the blackbody cavity into a spherical optical fiber was proposed. Influence of parameters of spherical fiber and blackbody cavity on coupling efficiency was analyzed. Results show that coupling efficiency firstly iTo improve coupling efficiency from blackbody source into fiber, a coupling model of light intensity from the blackbody cavity into a spherical optical fiber was proposed. Influence of parameters of spherical fiber and blackbody cavity on coupling efficiency was analyzed. Results show that coupling efficiency firstly increases and then decreases with the increase of radius of spherical fiber. When radius is around 85 μm, coupling efficiency reaches the maximum. Spherical fibers with radius from 65 μm to 105 μm were fabricated by fusion splicer. Experiments were carried out with spherical fibers and a fiber with flat end face. Results show that compared with the fiber with flat end face, coupling efficiency of spherical fiber is greatly improved, when radius is around 85 μm, coupling efficiency is improved by approximately 60%. The experimental results are consistent with the theoretical analysis..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0906001 (2020)
Combined Interrogation Algorithm of Amplitude Normalization and Minimum Mean Square Error for Fiber-optic Fabry-Perot Sensors
Jia-shuang FENG, Wei WANG, Xiong-xing ZHANG, Hai-bin CHEN, Zi-long GUO, Jia-xin SHEN, and Jun-ying ZHANG
A combined algorithm of amplitude normalization and minimum mean square error for the cavity length interrogation of fiber-optic Fabry-Perot sensors is proposed. An amplitude normalization method is introduced to realize the equiamplitude of both the reflected and the simulated spectral signals, which helps improving tA combined algorithm of amplitude normalization and minimum mean square error for the cavity length interrogation of fiber-optic Fabry-Perot sensors is proposed. An amplitude normalization method is introduced to realize the equiamplitude of both the reflected and the simulated spectral signals, which helps improving the interrogating accuracy. Significant increasing of interrogating accuracy compared with conventional algorithms is verified through numerical simulations. And, a 0.72 nm resolution of cavity length interrogation is achieved in real experiment..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0906002 (2020)
Optical Fiber Fabry-Perot Humidity Sensor by Graphene Quantum Dots
Ning WANG, Wen-hao TIAN, Hao-sheng ZHANG, Xiao-dan YU, Xiao-lei YIN, and Yong-gang DU
A kind of Fabry-Perot optical fiber humidity sensor is fabricated by normal single-mode optical fiber and Graphene Quantum Dots.By the established experimental system, the humidity response experiments were carried out in the relative humidity range of 11% RH ~85% RH. The sensitivity was 0.560 6 nm/%RH with 0.999 47 liA kind of Fabry-Perot optical fiber humidity sensor is fabricated by normal single-mode optical fiber and Graphene Quantum Dots.By the established experimental system, the humidity response experiments were carried out in the relative humidity range of 11% RH ~85% RH. The sensitivity was 0.560 6 nm/%RH with 0.999 47 linearity at humidity rising, and 0.565 5 nm/%RH sensitivity with 0.999 36 linearity at humidity falling. The experimental results showed that the humidity sensor has high humidity response sensitivity, good linear response characteristics and measurement repeatability. Furthermore, the temperature responding characteristic is also experimentally investigated. The good linear temperature responding results are got with 0.035 nm/℃ sensitivity, 0.012 41 residual sum of squares, 2.305×10-4 sensitivity stand error. The humidity response sensitivity is about 17 times of temperature response. Typical tests are given for dynamic response characteristics. The dynamic response data of interference spectrum wavelength drift under 43% RH showed fast dynamic response characteristic. The response time and recovery time were 6.5 s and 9.0 s respectively. The research results provide a beneficial exploration for developing low cost, easily fabricated and high sensitive optical fiber humidity sensor..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0906003 (2020)
Image Processing
Multiple Color Images Encryption via Compressive Holography and Spatial Multiplexing
Cheng ZHANG, Hai-tao XU, Yuan-yuan ZHU, Jun TANG, and Sui WEI
A method of multiple color images encryption via compressive holography and spatial multiplexing is proposed to solve the low encryption capacity and high distortion of decrypted images when using existing optical encryption methods to encrypt color images. In the optical encryption step, multiple color images encrypteA method of multiple color images encryption via compressive holography and spatial multiplexing is proposed to solve the low encryption capacity and high distortion of decrypted images when using existing optical encryption methods to encrypt color images. In the optical encryption step, multiple color images encrypted by different random phase masks. Combine space division multiplexing with modifying the Mach-Zehnder interferometer, which implemented for encrypting multiple color images simultaneously into one hologram by single shot. Combine space division multiplexing with modifying the Mach-Zehnder interferometer, which implemented for encrypting multiple color images simultaneously into one hologram by single shot. In the decryption step, the process of recording hologram can be regarded as a process of compressive sensing, the two-step iterative shrinkage/thresholding algorithm is used to solve the problem. The experimental results show that the proposed encryption system has a large encryption capacity and a high quality of decrypted color images, and the average peak signal to noise ratio only decreases about 2~5 dB of the decrypted images, which eliminate the influence of square field term in the on-line holography; and the random phase mask and the propagation distance both play the role as the key, which can provide high security. The color images can not be decrypted when the random phase mask is wrong or the propagation distance is only offset by 0.25%; and it has good robustness to noise and occlusion attacks. The quality of decrypted images decline slowly with the increasing noise. We can still be obtain the good decrypted results, when 80% of the encrypted hologram information is under occlusion attack..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0910001 (2020)
Imaging Systems
Optically Multiplexed Imaging for Increased Field of View
Liang ZHOU, Kai LIU, Zhao-hui LIU, Jing DUAN, and Zhi-guo LI
In order to simplify the multiplexing architecture and encoding method, a two-channels multiplexed imaging architecture was constructed with rotation encoding mirror, beamsplitter and optically imaging system. The subpixel accuracy shifts between superimposed images were proposed to automatically decide with features dIn order to simplify the multiplexing architecture and encoding method, a two-channels multiplexed imaging architecture was constructed with rotation encoding mirror, beamsplitter and optically imaging system. The subpixel accuracy shifts between superimposed images were proposed to automatically decide with features detection and registration. The system multiplexed matrics were built with the known shifts and the gradient projection for sparse reconstruction method was adopted to reconstruction the respctive scene based on six frames. The increase of field of view was verified with 2 times in the proposed realistic setting. Also, the proposed method can sucessfully disambiguate other scenes, which demonstrates its wide range of application. This method can effectively increase the field of view with the same focal plane array, and can be cost effective in developing wide field of view optically imaging system..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0911001 (2020)
Research on Non-uniformity Correction of Detector for Directional Polarimetric Camera
Bi-hai TU, Ping-ping YAO, Bing-huan MENG, Jian-wen WENG, Chan HUANG, and Jin HONG
The image non-uniformity is related to many factors such as lens, detector assembly, spatial stray light, etc. The single correction method can not distinguish the error source effectively. In view of the on orbit working mode of polarization imager based on integral time adjustment, the non-uniformity correction methoThe image non-uniformity is related to many factors such as lens, detector assembly, spatial stray light, etc. The single correction method can not distinguish the error source effectively. In view of the on orbit working mode of polarization imager based on integral time adjustment, the non-uniformity correction method of detector based on multi parameters is studied. Through the comprehensive test equipment of CCD detector, the datas of sensitive factors such as temperature, dark current, exposure time and specrtal response are obtained. After a seris of preprocessing of the image including removal of darkness signal, removal of smearing effect and temperature conpenstion, the low-frequency unbalanced response difference of the image surface is eliminated, and the high-frequency difference is effectively suppressed. The experimental results show that the photo response non-uniformity of 95% full well single frame data is reduced from 1.141% to 0.513%. After correction, the data noise is shown as shot noise. After correction, the detectorhas good dynamic range adjustment ability and linearity. The non-uniformity correction method based on multi parameters is used to provide data support for calibration correction and on orbit fast calculation of the instrument, and provide effective reference for the following polarization remote sensing instruments..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0911002 (2020)
Instrumentation, Measurement and Metrology
Research on Laser Velocimeter for Overspeed Detection on Highways
Wen-tao LI, Hao TANG, and Jian ZHOU
In order to reduce the illegal overspeed on highways and improve the traffic safety monitoring system, a portable laser Doppler velocity measuring system for long-distance work is proposed. The principle of laser Doppler velocimeter and the method of beam transformation are described in detail. And using the structure In order to reduce the illegal overspeed on highways and improve the traffic safety monitoring system, a portable laser Doppler velocity measuring system for long-distance work is proposed. The principle of laser Doppler velocimeter and the method of beam transformation are described in detail. And using the structure of the double lens telescope system, the laser velocimeter for highway overspeed detection is built. The results of theory and experiment show that this laser Doppler velocity measuring system has the characteristics of long working distance and large depth of field, and the vehicle's velocity can be obtained with high accuracy. Compared with traditional laser velocimeters, the center working distance and the depth of field are increased by this portable laser Doppler velocity measuring system. The center working distance of this novel laser Doppler velocimeter is 10 m; the depth of field is ±1 m, and the velocity measurement accuracy can reach to 0.1%..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0912001 (2020)
Determining the Junction Temperature of Two Phosphors-converted LED Based on Spectral Feature Parameters of the Chip
Feng RAO, Tao FANG, Zi-ling WANG, and Chen CHEN
The junction temperatures of LED with different ambient temperatures and drive currents were measured with the Forward Voltage method, at the same time, the normalized spectral distributions were measured with spectrometer.The specific spectral distribution of blue chip was selected to calculate its centroid wavelengthThe junction temperatures of LED with different ambient temperatures and drive currents were measured with the Forward Voltage method, at the same time, the normalized spectral distributions were measured with spectrometer.The specific spectral distribution of blue chip was selected to calculate its centroid wavelength and full width at half maximum, and then the relationships among these two parameters, drive current and junction temperature were obtained. At last, the junction temperature of the LED at the lighting condition was obtained with the relationships and the measured spectral feature parameters of the chip. It was found that for the junction temperature changed with ambient temperature, the measured error of this method and (B+Y+R)/B method were both about 2 ℃, and no statistical significance. For the junction temperature changed with drive current, the measured error of this method was always 2 ℃. However, the error of the (B+Y+R)/B method was positively correlated with the current, with the change rate of 0.048 ℃/mA. Therefore, the established method was suitable for determining the junction temperature with the change of not only ambient temperature, but drive current, and it was also accurate when LED lighting for a long time without re-calibration, which showed significant technical advantages..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0912002 (2020)
A L-K Local Optical-flow-based Coordinate Profilometry by Using the Capture Line in Space
Ping SUN, Chao FAN, Qing DAI, Yu-xin TANG, Zhi-fang LEI, and Chun-hua HU
A technique based on L-K local optical flow algorithm for retrieving the height distribution of a measured surface is proposed by the calculation of the coordinates between the capture line and projection line in space. The measuring system is composed of a CCD camera and a projector which project a grating pattern witA technique based on L-K local optical flow algorithm for retrieving the height distribution of a measured surface is proposed by the calculation of the coordinates between the capture line and projection line in space. The measuring system is composed of a CCD camera and a projector which project a grating pattern with a small angle. The height distribution of a measured surface can be calculated directly by using the intersection coordinates of the projected line and the captured line, where the changes of the observation position between two fringe patterns caused by the measured surface can be calculated by L-K optical flow algorithm. The theoretical relationship between the optical flow and the height of the measured object at the intersection of the projected light and the line of sight under the projection condition of the point source is established. Simulation and experimental results show that the proposed method can retrieve the height of the measured object surface accurately. Different from traditional shape measurement methods, the proposed surface shape measurement technique using captured line and optical flow does not need to collect multiple fringe images, nor need to calculate the fringe frequency and the phase distribution, but only needs two fringe images to retrieve the height distribution of the measured surface..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0912003 (2020)
Lasers and Laser Optics
Generation of Broadband Supercontinuum Source with Pulse Width of One Hundred Femtosecond
Zheng-yi LIU, Shuang-long LIU, Ai-wang HUANG, Wei LIU, and Dan-ni CHEN
A method of generating broadband supercontinuum pulses is proposed, and it is a prefer light source for coherent Raman spectroscopy.A 1 064 nm femtosecond laser was used to pump the normal dispersion photonic crystal fiber, and then a pair of gratings was used to compress the pulse. Then a supercontinuum light source wA method of generating broadband supercontinuum pulses is proposed, and it is a prefer light source for coherent Raman spectroscopy.A 1 064 nm femtosecond laser was used to pump the normal dispersion photonic crystal fiber, and then a pair of gratings was used to compress the pulse. Then a supercontinuum light source with a pulse width of 178 fs and a spectral range of 760~1 300 nm was obtained.The temporary spectrum structure of the supercontinuum pulse was analyzed. The results demonstrated that its spectrum is basically linearly and smoothly distributed, but the pulse width reaches 1.43 ps, and the time delay between different spectral frequencies is quite large. Therefore, a pair of gratings is used for dispersion compensation. In addition, although increasing the power of pump light can increase the spectral broadening, it will also introduce higher-order dispersion, which will increase complexities to the following dispersion compensation. In the end, to verify the performance of the supercontinuum in Coherent Anti-stokes Raman Scattering (CARS), three-color CARS spectrum detection system was built using the supercontinuum, and the CARS spectrum of the benzonitrile solution was measured, and all vibration modes in the range of 3 200 cm-1 was obtained simultaneously..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0914002 (2020)
Microscopy
Progress and Prospect of Research on Single-molecule Localization Super-resolution Microscopy(Invited Review)
Sha AN, Dan DAN, Xiang-hua YU, Tong PENG, and Bao-li YAO
Super-resolution optical microscopy breaks through the diffraction limit and becomes a powerful tool for the modern biomedical research with the development of novel fluorescence probes, advanced lasers, high sensitivity photodetectors, etc. Single-molecule Localization Microscopy (SMLM), as one of the super-resolutionSuper-resolution optical microscopy breaks through the diffraction limit and becomes a powerful tool for the modern biomedical research with the development of novel fluorescence probes, advanced lasers, high sensitivity photodetectors, etc. Single-molecule Localization Microscopy (SMLM), as one of the super-resolution technologies, can resolve the subcellular structures in nanoscale by using the photoswitching effect of certain fluorescence probes. In this paper, the principle and implementation of SMLM are introduced, the applications in the fields of cytobiology, tissue biology and neuroscience are presented, furthermore, the development trends and the futher investigated directions of this technique are discussed, providing references for the relevant research fields. The continuous innovation of super-resolution microscopy will promote the development of life science..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0918001 (2020)
Optical Design and Fabrication
Influence of Weight Function on Progressive Addition Lens Design
Jian-dong GAO, Hua-zhong XIANG, Nian-ning LI, Cheng WANG, Gang ZHENG, Song-lin ZHUANG, and Da-wei ZHANG
In order to study the influence of the weight distribution function on lens design, on the basis of constructing the minimization model, the spline interpolation method was used to process the weight function of the transition region, and three groups of weight distribution functions were designed to connect the high wIn order to study the influence of the weight distribution function on lens design, on the basis of constructing the minimization model, the spline interpolation method was used to process the weight function of the transition region, and three groups of weight distribution functions were designed to connect the high weight region and the low weight region. According to different weight distribution functions, the corresponding progressive addition lens was designed, and the simulation, machining and evaluation were carried out. The experimental results showed that the weight distribution matrix has an impact on the optical performance of the lens. The faster the weight changes in the transition region of the average curvature and the difference between the principal curvature of the surface, the better the optical performance of the lens. Therefore, using the weight function with fast change of transition region is beneficial to reduce the astigmatism around the lens and optimize the lens power and astigmatism distribution..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0922001 (2020)
Optical Design and Tolerance Analysis of Freeform Automotive Head-up Display
Yang-liu ZHANG, Zhou-ping SU, Hong-xiang PAN, Xing-tao CHEN, and Wen-yu ZHANG
A freeform optical system of automotive Head-Up Display (HUD) was designed. In the initial layout design of the HUD optical system, the sample points on two optical freeform surfaces of the HUD optical system are calculated by the seed curve extension algorithm. And the two freeform surfaces are expressed by the extendA freeform optical system of automotive Head-Up Display (HUD) was designed. In the initial layout design of the HUD optical system, the sample points on two optical freeform surfaces of the HUD optical system are calculated by the seed curve extension algorithm. And the two freeform surfaces are expressed by the extended polynomials. Then the ray tracing is performed for the initial layout of the HUD optical system at center field of view with 0.5 mm ray sampling interval. The results show that the performance of the initial layout of the HUD optical system is the diffraction-limited, which can be used as the starting point for further optimization at full field of view. After optimization, the final HUD optical system is obtained. In order to simulate the observation of human eyes, several test points in the Eyebox are taken as object points, which are imaged on the image plane by the HUD optical system. The modulation transfer function plots of the several test points are greater than 0.5 at 6 lp/mm, which are close to diffraction limit. And the distortions of the final HUD system are less than 2%. Finally, the manufacture tolerances of two optical freeform surfaces are analyzed. The results show that the modulation transfer function plots of the HUD optical system are higher than 0.3 with the tolerance PV values of 0.42 μm and 0.62 μm of the two optical freeform surfaces respectively. For the current machining capacity, the tolerance requirements are reasonable..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0922002 (2020)
Optical Devices
Research on Partial Negative Curvature Terahertz Hollow-core Waveguide
Qi-yuan MU, Yuan-feng ZHU, Lu XUE, Ya-ni ZHANG, De-peng KONG, Zheng-quan HE, Hong-jun LIU, and Li-li WANG
A novel partial negative curvature anti-resonance hollow-core terahertz waveguide is proposed. The waveguide cladding consists of two parts, one part is composed of a dielectric circular tube, which provides a part of the negative curvature boundary for the core; the other part is composed of a plurality of rectangularA novel partial negative curvature anti-resonance hollow-core terahertz waveguide is proposed. The waveguide cladding consists of two parts, one part is composed of a dielectric circular tube, which provides a part of the negative curvature boundary for the core; the other part is composed of a plurality of rectangular dielectric layers, and multiple dielectric layers for reducing confinement loss. This waveguide structure does not introduce a new cladding node while adding anti-resonant layers, and it is easy to achieve broadband low-loss transmission of terahertz waves. The full vector finite element method is used for the numerical simulation of the waveguide, and the broadband low loss characteristic is investigated. Based on the simulation analysis, the designed waveguide is printed via 3D printing technology, and the transmission characteristics are tested using a terahertz time-domain spectroscopy system. Experimental results show that the transmission loss of this negative curvature anti-resonance terahertz waveguide is less than 10 dB/m in the range of 0.29~0.42 THz, which is in good agreement with the numerical simulation..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0923001 (2020)
Design of Metasurface Lens with Two Focal Spots Based on Polarization Response
Peng-jiu ZHAO, Shou-peng LIU, Yu LUO, Wei REN, and Xiao-hu CHEN
A focusing lense with two focal spots based on dielectric metasurface was designed which can extend the focus axially. The device modulates the propagation phase and the geometric phase at the same time and realizes the independent control of a group of orthogonal polarized incident light by varying the aspect ratio anA focusing lense with two focal spots based on dielectric metasurface was designed which can extend the focus axially. The device modulates the propagation phase and the geometric phase at the same time and realizes the independent control of a group of orthogonal polarized incident light by varying the aspect ratio and the rotation angle of the titanium dioxide pillars. The designed metasurface focuses the left-handed and right-handed circularly polarized light at contiguous positions to extend the focus axially. We extend the length of focus twice as initial value at 650 nm wavelength and maintain the lateral width of the focus in the meantime. The optimization of the focus shape and the switch of focus position with different focal lengths can be realized by adjusting the incident light into an elliptically polarized light..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0923002 (2020)
Physical Optics
Multiple Magnetic Fano Resonances Based on Single-split Ring and Double-split Disk Structure
Qi-qiang NIU, Yi-ping HUO, Xue-ying JIANG, Chen ZHOU, Yi-yuan GUO, Yi-bo HOU, Qian HE, and Xiang-xiang HAO
The surface plasmon resonances of a nanostructure composed of a single-split ring and a double-split disk is studied theoretically by the finite element method. When the incident light is normal to the structure surface, a magnetic Fano resonance can be generated by the interference between a bright magnetic mode and aThe surface plasmon resonances of a nanostructure composed of a single-split ring and a double-split disk is studied theoretically by the finite element method. When the incident light is normal to the structure surface, a magnetic Fano resonance can be generated by the interference between a bright magnetic mode and a dark magnetic mode. High order magnetic modes and double magnetic Fano resonances can be generated when the double-split disk, the cavity, and the gap of the single-split ring offset together along the negative x-axis. On the basis of this structure, further modulating the gap width of the single-split ring, magnetic modes intensity is enhanced in the near-infrared region and triple magnetic Fano resonances is generated; similarly, by modulating the upper split angle of the double-split disk, high-order magnetic mode is obtained in the visible region and triple magnetic Fano resonances is generated. In addition, the maximum sensitivity and magnetic field enhancement of the structure can reach 1 400 nm/RIU and 69.7, respectively. These optical properties make the structure has potential application value in the field of ultra-sensitive biosensor and multi-control magnetic Fano switch..
Acta Photonica Sinica
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 0926001 (2020)
Thin Films
Infrared Indium Oxide Hf-doped Transparent Conductive Films
Feng TIAN, Ran BI, Wen-yuan ZHAO, Feng-bo HAN, Ya-dan LI, Chuan-tao ZHENG, and Yi-ding WANG
High-quality indium Hf-doped oxide (IHfO) films were prepared on quartz and ZnSe substrates by RF magnetron sputtering and annealing. The doping ratio of In2O3:HfO2 was 98wt.%:2wt. %. The composition of the film and the photoelectric properties of the 3~5 μm infrared band were tested and analyzed. The effects of annealHigh-quality indium Hf-doped oxide (IHfO) films were prepared on quartz and ZnSe substrates by RF magnetron sputtering and annealing. The doping ratio of In2O3:HfO2 was 98wt.%:2wt. %. The composition of the film and the photoelectric properties of the 3~5 μm infrared band were tested and analyzed. The effects of annealing temperature, film thickness and oxygen flow rate on the properties of the film were analyzed. The results of XRD, SEM and XPS show that the prepared IHfO film has the stereo-structure of indium oxide. The doping of germanium does not affect the growth direction of indium oxide, but it leads to the decrease of lattice spacing, and the new hybridization of germanium and indium electrons track. The FTIR test results show that the transmittance of IHfO film in the 3~5 μm band decreases with the increase of annealing temperature, and the film deposited on the ZnSe substrate has a more stable transmittance. When the film thickness is 100 nm, the average transmission rate in the 3~5 μm is around 68%. The Hall Effect test results show that with the increase of oxygen flow rate, the resistivity of IHfO film increases gradually, the carrier concentration decreases, and the Hall mobility changes little. The analysis shows that grain boundary scattering is the main factor affecting the mobility of IHfO film. The optimal resistivity of the film is 3.3×10-2Ω·cm when the oxygen flow rate is 0.3 sccm. Compared with the commercial visible-band Indium Tin Oxide (ITO) thin films, the IHfO thin films prepared in this paper can be better applied in gas detection, infrared guidance and other related fields in the 3~5 μm infrared band..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0931001 (2020)
Light Trapping Enhancement of Composite Rough Surface ZnO:Al Gratings in Thin Film Silicon Solar Cells
Ren-chen LIU, Jing LU, He-ping CHENG, Zhao-ming LIANG, and Yang LIU
This paper discussed the influence of composite rough surface aluminum-doped zinc oxide (ZnO:Al) gratings on light trapping efficiency of thin film silicon solar cells. Rough surface was characterized by correlation length (lcor) and average height (have), and superimposed on a one-dimension sine ZnO:Al grating with 98This paper discussed the influence of composite rough surface aluminum-doped zinc oxide (ZnO:Al) gratings on light trapping efficiency of thin film silicon solar cells. Rough surface was characterized by correlation length (lcor) and average height (have), and superimposed on a one-dimension sine ZnO:Al grating with 980 nm period and 160 nm groove depth. The short-circuit current was higher when front electrode AZO grating had smaller lcor and larger have. As lcor=0.01, short-circuit current raised with the increase of have value, from 21.93 mA/cm2 of have=0.05 to 23.80 mA/cm2 of have=0.80. When used as back electrode, the short-circuit current decreased with the increase of have, from 25.50 mA/cm2 of have=0.05 to 24.81 mA/cm2 of have=0.80. Composite rough surface ZnO:Al grating and non-rough surface ZnO:Al grating were fabricated by chemical etching and direct current sputter respectively. Reflectivity results showed that total reflection of composite rough surface ZnO:Al grating (8.3%) was 1.9% lower than that of non-rough surface ZnO:Al grating (10.2%), and specular reflection of composite rough surface ZnO:Al grating (4.7%) was 2.1% lower than that of non-rough surface ZnO:Al grating (6.8%). Rigorous coupled wave method was used to simulate reflection of ZnO:Al grating with and non- rough surface. Results further confirmed that composite rough ZnO:Al grating was more suitable for front electrode of thin film solar cells due to its better anti-reflection effect and could obtain a larger short-circuit current. Non-rough surface ZnO:Al grating could reflect more photons back to silicon absorption layer due to its higher reflection and was more suitable for back electrode..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 49, Issue 9, 0931002 (2020)
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