Journals >Chinese Optics Letters
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2011
Volume: 9 Issue 4
24 Article(s)
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Atomic and Molecular Physics
Proposal of a dual-ball atomic fountain clock
Chunyan Shi, Rong Wei, Zichao Zhou, Tang Li, and Yuzhu Wang
A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time, which works like "two fountains", but is more compact since most components of the "two fountains" are shared. It is expected to improve the stability of the fountain markedly.A simple improved structure is designed to trap and launch two cold atomic balls vertically at the same time, which works like "two fountains", but is more compact since most components of the "two fountains" are shared. It is expected to improve the stability of the fountain markedly..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040201 (2011)
Analysis of the time-domain spectrum of hydrogen in electric field near helium surface
Xiaoqing Gong, and Guangcan Yang
The Ryderberg electronic wave packet dynamics of hydrogen atom near helium surface in an electric field is investigated using the semiclassical method. The autocorrelation function is calculated when the photoionized electron is excited by a short laser pulse for different atom-surface separations. The results show thaThe Ryderberg electronic wave packet dynamics of hydrogen atom near helium surface in an electric field is investigated using the semiclassical method. The autocorrelation function is calculated when the photoionized electron is excited by a short laser pulse for different atom-surface separations. The results show that new recurrences appear because of the helium surface, and the number of recurrent peaks increases with the decrease in atom-surface distance. The new feature is ascribed to the bifurcation of new closed orbits in the classical dynamics of the photoionized electron. Therefore, surface properties have a significant effect on the spectrum of nearby atoms or ions..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040202 (2011)
Holography
Holographic imaging of full-color real-existing three-dimensional objects with computer-generated sequential kinoforms
Huadong Zheng, Tao Wang, Linmao Dai, and Yingjie Yu
We propose a computational method for generating sequential kinoforms of real-existing full-color threedimensional (3D) objects and realizing high-quality 3D imaging. The depth map and color information are obtained using non-contact full-color 3D measurement system based on binocular vision. The obtained full-color 3DWe propose a computational method for generating sequential kinoforms of real-existing full-color threedimensional (3D) objects and realizing high-quality 3D imaging. The depth map and color information are obtained using non-contact full-color 3D measurement system based on binocular vision. The obtained full-color 3D data are decomposed into multiple slices with RGB channels. Sequential kinoforms of each channel are calculated and reconstructed using a Fresnel-diffraction-based algorithm called the dynamicpseudorandom-phase tomographic computer holography (DPP-TCH). Color dispersion introduced by different wavelengths is well compensated by zero-padding operation in the red and green channels of object slices. Numerical reconstruction results show that the speckle noise and color-dispersion are well suppressed and that high-quality full-color holographic 3D imaging is feasible. The method is useful for improving the 3D image quality in holographic displays with pixelated phase-type spatial light modulators (SLMs)..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040901 (2011)
Lasers and Laser Optics
Millijoule pulse energy picosecond fiber chirped-pulse amplification system
Zhi Yang, Xiaohong Hu, Yishan Wang, Wei Zhang, and Wei Zhao
The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium (Yb)-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification (CPA) system aThe efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium (Yb)-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification (CPA) system and generates mode-locked pulses with hundreds of picosecond widths. Two kinds of large-mode-area (LMA) double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier. All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio (SNR). The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission (ASE) is suppressed to better than 30 dB, and the onset of stimulated Raman scattering is excluded..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041401 (2011)
A 657-nm narrow bandwidth interference filter-stabilized diode laser
Zhengbo Wang, Xiaokai Lv, and Jingbiao Chen
We present a 657-nm external cavity diode laser (ECDL) system, where the output frequency is stabilized by a narrow-band high transmission interference filter. This novel diode laser system emits laser with an instantaneous linewidth of 7 kHz and a broadened linewidth of 432 kHz.We present a 657-nm external cavity diode laser (ECDL) system, where the output frequency is stabilized by a narrow-band high transmission interference filter. This novel diode laser system emits laser with an instantaneous linewidth of 7 kHz and a broadened linewidth of 432 kHz..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041402 (2011)
Generation of tunable multi-wavelength optical short pulses using self-seeded Fabry-Perot laser diode and tilted multimode fiber Bragg grating
Tongjian Cai, Yunqi Liu, Xiaobei Zhang, and Tingyun Wang
We experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD) with an external cavity formed by a tilted multimode fiber Bragg grating. Dual- and triple-wavelength pulses arWe experimentally demonstrate the simultaneous generation of tunable multi-wavelength picosecond laser pulses using a self-seeding configuration that consists of a gain-switched Fabry-Perot laser diode (FPLD) with an external cavity formed by a tilted multimode fiber Bragg grating. Dual- and triple-wavelength pulses are obtained and tuned in a flexible manner by changing the temperature of the FPLD. The side mode suppression ratio larger than 25 dB is achieved at different dual- and triple-wavelengths and the typical pulsewidth of the output pulses is ?70 ps. In the experiment, the wavelength separation can be narrowed to 0.57 nm..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041403 (2011)
Phase noise measurement of high-power fiber amplifiers
Hu Xiao, Xiaolin Wang, Yanxing Ma, Bing He, Pu Zhou, Jun Zhou, and Xiaojun Xu
We measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density. Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifieWe measure the phase fluctuation in a high-power fiber amplifier using a multi-dithering technique. Its fluctuation property is qualitatively analyzed by the power spectral density and integrated spectral density. Low frequency fluctuations caused by the environment are dominant in the phase fluctuations in an amplifier, whereas the high frequency components related to laser power affect the control bandwidth. The bandwidth requirement of the active phase-locking is calculated to be 300 Hz, 670 Hz, 1.6 kHz, and 3.9 kHz under the output power of 25, 55, 125, and 180 W, respectively. The approximately linear relationship between the control bandwidth and laser power needs to be further investigated..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041404 (2011)
Passively mode-locked grown-together composite YVO4/Nd:YVO4 crystal laser with a semiconductor saturable absorber mirror under 880-nm direct pumping
Fangqin Li, Nan Zong, Zhichao Wang, Lin Han, Yong Bo, Qinjun Peng, Dafu Cui, and Zuyan Xu
A passively mode-locked grown-together composite YVO4/Nd:YVO4 crystal laser is demonstrated with a semiconductor saturable absorber mirror by 880-nm laser-diode direct pumping. Under the absorbed pump power of 24.9 W, a maximum output power of 10.5 W at the repetition rate of 77 MHz is obtained, corresponding to the opA passively mode-locked grown-together composite YVO4/Nd:YVO4 crystal laser is demonstrated with a semiconductor saturable absorber mirror by 880-nm laser-diode direct pumping. Under the absorbed pump power of 24.9 W, a maximum output power of 10.5 W at the repetition rate of 77 MHz is obtained, corresponding to the optical-optical conversion efficiency of 42.1% and the slope efficiency of 53.4%. The pulse width measured is 33 ps at the output power of 10 W..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041405 (2011)
A robust method for frequency stabilization of 556-nm laser operating at the intercombination transition of ytterbium
Zhuanxian Xiong, Yun Long, Huixing Xiao, Xi Zhang, Lingxiang He, and Baolong Lv
A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with 1S0-3P1 intercombination transition of ytterbium (Yb) atoms. A 556-nm laser light using a single-pass second harmonic generation (SHG) is obtained in a periodically poled MgO:LiNbO3 (PPLN) crystal pumped by a fiber laser aA frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with 1S0-3P1 intercombination transition of ytterbium (Yb) atoms. A 556-nm laser light using a single-pass second harmonic generation (SHG) is obtained in a periodically poled MgO:LiNbO3 (PPLN) crystal pumped by a fiber laser at 1111.6 nm. A robust frequency stabilization method which facilitates the control of laser frequency with an accuracy better than the natural linewidth (187 kHz) of the intercombination line is developed. The short-term frequency jitter is reduced to less than 100 kHz by locking the laser to a home-made reference cavity. A slow frequency drift is sensed by the 556-nm fluorescence signal of an Yb atomic beam excited by one probe beam and is reduced to less than 50-kHz by a computer-controlled servo system. The laser can be stably locked for more than 5 h. This frequency stabilization method can be extended to other alkaline-earth-like atoms with similar weak intercombination lines..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041406 (2011)
High repetition rate Tm:Ho:LuLiF master-oscillator and Tm-doped fiber power-amplifier system
Ting Yu, Shijiang Shu, and Weibiao Chen
A high repetition rate Tm:Ho:LuLiF master-oscillator and polarization-maintaining (PM) Tm-doped fiber power-amplifier system is presented. A 11.3-kHz, 0.4-nm line width, 0.89-W Tm:Ho:LuLiF seed laser is developed. Using a two-stage PM Tm-doped fiber power amplifier system, 32.4-W output power is obtained with 0.4-nm liA high repetition rate Tm:Ho:LuLiF master-oscillator and polarization-maintaining (PM) Tm-doped fiber power-amplifier system is presented. A 11.3-kHz, 0.4-nm line width, 0.89-W Tm:Ho:LuLiF seed laser is developed. Using a two-stage PM Tm-doped fiber power amplifier system, 32.4-W output power is obtained with 0.4-nm line width at a central wavelength of 2058.5 nm, corresponding to 0.66-W seed laser. The laser spectrum and pulse profile are measured..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041407 (2011)
Coherent addition of gratings for chirped-pulse-amplified lasers based on near-field and far-field measurements
Yuchuan Yang, Hui Luo, Xiao Wang, Fuquan Li, Xiaojun Huang, Bin Feng, and Feng Jing
The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings. We present a computer-control test system utilizing near-field interferenceThe development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings. We present a computer-control test system utilizing near-field interference and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor. In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT) of the individual interference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference. Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041408 (2011)
Fiber Optics and Optical Communications
Dispersion flattened photonic crystal fiber with high nonlinearity for supercontinuum generation at 1.55 \mum
Long Zheng, Xia Zhang, Xiaomin Ren, Huifang Ma, Lei Shi, Yamiao Wang, and Yongqing Huang
A robust design for a photonic crystal fiber (PCF) based on pure silica with small normal dispersion and high nonlinear coefficient for its dual concentric core structure is presented. This design is suitable for flat broadband supercontinuum (SC) generation in the 1.55-μm region. The numerical results show that the noA robust design for a photonic crystal fiber (PCF) based on pure silica with small normal dispersion and high nonlinear coefficient for its dual concentric core structure is presented. This design is suitable for flat broadband supercontinuum (SC) generation in the 1.55-μm region. The numerical results show that the nonlinear coefficient of the proposed eight-ring PCF is 33.8 W?1.km?1 at 1550 nm. Ultraflat dispersion with a value between -1.65 and -0.335 ps/(nm.km) is obtained ranging from 1375 to 1625 nm. The 3-dB bandwidth of the SC is 125 nm (1496–1621 nm), with a fiber length of 80 m and a corresponding input peak power of 43.8 W. The amplitude noise is considered to be related to SC generation. For practical fabrication, the influence of the random imperfections of airhole diameters on dispersion and nonlinearity is discussed to verify the robustness of our design..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040601 (2011)
Novel scheme enabling broadcast signal transmission in WDM passive optical network
Xuejiao Ma, and Chaoqin Gan
We present a novel method for providing broadcast signal transmission in a wavelength division multiplexing passive optical network (WDM-PON). An unmodulated optical carrier for downstream transmission and a pair of unmodulated single-side band subcarriers are utilized for broadcast delivery and upstream transmission, We present a novel method for providing broadcast signal transmission in a wavelength division multiplexing passive optical network (WDM-PON). An unmodulated optical carrier for downstream transmission and a pair of unmodulated single-side band subcarriers are utilized for broadcast delivery and upstream transmission, respectively. System performance at 2.5-Gb/s down/upstream and 2.5-Gb/s broadcast transmission is also investigated..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040602 (2011)
Rerouting end-face-TIR capable rays to significantly increase evanescent wave signal power
Jianjun Ma, Yasser Chiniforooshan, Huacai Chen, Jiahua Chen, Wojtek J. Bock, and Andrea Cusano
The critical findings associated with end-face total internal reflection (TIR) phenomemon we proved before are reported. In particular, these findings reveal that the end-face-TIR capable rays experience enormous mode mixing when encountering a roughened end face. As a result, 94% of the overall detectable power is conThe critical findings associated with end-face total internal reflection (TIR) phenomemon we proved before are reported. In particular, these findings reveal that the end-face-TIR capable rays experience enormous mode mixing when encountering a roughened end face. As a result, 94% of the overall detectable power is contributed by this effect. With a smooth fiber end face, this figure is mere 52%. We interpret the mechanism behind these unusual phenomena and its significance for the performance enhancement of fiber optic evanescent wave sensor..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 040603 (2011)
Imaging Systems
Recognizing cat-eye targets with dual criterions of shape and modulation frequency
Ximing Ren, and Li Li
We present an image recognition method to distinguish targets with cat-eye effect from the dynamic background based on target shape and modulation frequency. Original image sequences to be processed are acquired through an imaging mechanism that utilizes a pulsed laser as active illuminator and an industrial camera as We present an image recognition method to distinguish targets with cat-eye effect from the dynamic background based on target shape and modulation frequency. Original image sequences to be processed are acquired through an imaging mechanism that utilizes a pulsed laser as active illuminator and an industrial camera as detection device. There are two criterions to recognize a target: one exploits shape priors and the other is the active illuminator’s modulation frequency. The feasibility of the proposed method and its superiority over the single criterion method have been demonstrated by practical experiments..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041101 (2011)
Medical Optics and Biotechnology
Voxel classification methodology for rapid Monte Carlo simulation of light propagation in complex media
Nunu Ren, Heng Zhao, Shouping Zhu, Xiaochao Qu, Hongliang Liu, Zhenhua Hu, Jimin Liang, and Jie Tian
Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field. However, obtaining an accurate result using the method is quite time-consuming, especially because the boundary of the media is complex. A voxel classification method is proposed to reduce Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field. However, obtaining an accurate result using the method is quite time-consuming, especially because the boundary of the media is complex. A voxel classification method is proposed to reduce the computation cost. All the voxels generated by dividing the media are classified into three types (outside, boundary, and inside) according to the position of the voxel. The classified information is used to determine the relative position of the photon and the intersection between photon path and media boundary in the MC method. The influencing factors and effectiveness of the proposed method are analyzed and validated by simulation experiments..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041701 (2011)
Quantum Optics
Enhancing entanglement generation of two atoms in a cavity with white noise using classical driving fields
Jiansong Zhang, and Aixi Chen
We investigate the entanglement dynamics of a quantum system consisting of two two-level atoms in a cavity with classical driving fields in the presence of white noise. The cavity is initially prepared in the vacuum state. Generally, the entanglement of two atoms decreases with the intensity of the thermal fields and tWe investigate the entanglement dynamics of a quantum system consisting of two two-level atoms in a cavity with classical driving fields in the presence of white noise. The cavity is initially prepared in the vacuum state. Generally, the entanglement of two atoms decreases with the intensity of the thermal fields and the coupling strength of the two-level atoms to the thermal fields. However, we find that the entanglement of the quantum system can be enhanced by adjusting the frequency and the strength of the classical driving fields in the presence of white noise..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 042701 (2011)
Materials
Stacking-faults-free zinc blende GaAs/AlGaAs axial heterostructure nanowires during vapor-liquid-solid growth
Jingwei Guo, Hui Huang, Xiaomin Ren, Xin Yan, Shiwei Cai, Yongqing Huang, Qi Wang, Xia Zhang, and Wei Wang
Pure zinc blende structure GaAs/AlGaAs axial heterostructure nanowires (NWs) are grown by metal organic chemical vapor deposition on GaAs(111) B substrates using Au-catalyzed vapor-liquid-solid mechanism. Al adatom enhances the influence of diameters on NWs growth rate. NWs are grown mainly through the contributions frPure zinc blende structure GaAs/AlGaAs axial heterostructure nanowires (NWs) are grown by metal organic chemical vapor deposition on GaAs(111) B substrates using Au-catalyzed vapor-liquid-solid mechanism. Al adatom enhances the influence of diameters on NWs growth rate. NWs are grown mainly through the contributions from the direct impingement of the precursors onto the alloy droplets and not so much from adatom diffusion. The results indicate that the droplet acts as a catalyst rather than an adatom collector..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041601 (2011)
Nonlinear Optics
Generation of isolated attosecond pulses with a specific waveform two-color laser field
Jinping Yao, Yao Li, and Ya Cheng
We theoretically propose a new method for generating intense isolated attosecond pulses during high-order harmonic generation (HHG) process by accurately controlling electron motion with a two-color laser field, which consists of an 800-nm, 4-fs elliptically polarized laser field and a 1400-nm, ~43-fs linearly polarizeWe theoretically propose a new method for generating intense isolated attosecond pulses during high-order harmonic generation (HHG) process by accurately controlling electron motion with a two-color laser field, which consists of an 800-nm, 4-fs elliptically polarized laser field and a 1400-nm, ~43-fs linearly polarized laser field. With this method, the supercontinua with a spectral width above 200 eV are obtained, which can support a ~15-as isolated pulse after phase compensation. Classical and quantum analyses explain the controlling effects well. In particular, when the pulse duration of the 800-nm laser field increases to 20-fs, sub-100-as isolated pulses can be obtained even without any phase compensation..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041901 (2011)
Bidirectionally tunable all-optical switch based on multiple nano-structured resonators using backward quasi-phase-matching
Jun Xie, Yuping Chen, Wenjie Lu, and Xianfeng Chen
Based on the second-order nonlinearity, we present a bidirectional tunable all-optical switch at C-band by introducing backward quasi-phase-matching technique in Mg-doped periodically poled lithium niobate (MgO:PPLN) waveguide with a nano-structure called multiple resonators. Two injecting forward lights and one backwaBased on the second-order nonlinearity, we present a bidirectional tunable all-optical switch at C-band by introducing backward quasi-phase-matching technique in Mg-doped periodically poled lithium niobate (MgO:PPLN) waveguide with a nano-structure called multiple resonators. Two injecting forward lights and one backward propagating light interact with difference frequency generations. The transmission of forward signal and backward idler light can be modulated simultaneously with the variation of control light power based on the basic “phase shift” structure of a single resonator. In this scheme, all the results come from our simulation. The speed of this bidirectional optical switch can reach to femtosecond if a femtosecond laser is used as the control light..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041902 (2011)
Image Processing
Multi-focus image fusion algorithm based on shearlets
Qiguang Miao, Cheng Shi, Pengfei Xu, Mei Yang, and Yaobo Shi
Shearlets not only possess all properties that other transforms have, but also are equipped with a rich mathematical structure similar to wavelets, which are associated to a multi-resolution analysis. Recently, shearlets have been used in image denoising, sparse image representation, and edge detection. However, its apShearlets not only possess all properties that other transforms have, but also are equipped with a rich mathematical structure similar to wavelets, which are associated to a multi-resolution analysis. Recently, shearlets have been used in image denoising, sparse image representation, and edge detection. However, its application in image fusion is still under study. In this letter, we study the feasibility of image fusion using shearlets. Fusion rules of larger high-frequency coefficients based on regional energy, regional variance, and absolute value are proposed because shearlet transform can catch detailed information in any scale and any direction. The fusion accuracy is also further improved by a region consistency check. Several different experiments are adopted to prove that fusion results based on shearlet transform can acquire better fusion quality than any other method..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041001 (2011)
Enhanced reconstruction of partially occluded objects with occlusion removal in synthetic aperture integral imaging
Zhiliang Zhou, Yan Yuan, Xiangli Bin, and Qian Wang
Synthetic aperture integral imaging provides the ability to reconstruct partially occluded objects from multi-view images. However, the reconstructed images suffer from degraded contrast due to the superimposition of foreground defocus blur. We propose an algorithm to remove foreground occlusions before reconstructing Synthetic aperture integral imaging provides the ability to reconstruct partially occluded objects from multi-view images. However, the reconstructed images suffer from degraded contrast due to the superimposition of foreground defocus blur. We propose an algorithm to remove foreground occlusions before reconstructing backgrounds. Occlusions are identified by estimating the color variance on elemental images and then deleting it in the final synthetic image. We demonstrate the superiority of our method by presenting experimental results as well as comparing our method with other approaches..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041002 (2011)
Indirect building localization based on a prominent solid landmark from a forward-looking infrared imagery
Xiaoping Wang, Tianxu Zhang, and Xiaoyu Yang
A novel indirect building localization technique based on a prominent solid landmark from a forward-looking infrared imagery is proposed to localize low, deeply buried, or carefully camouflaged buildings in dense urban areas. First, the widely used effective methods are applied to detect and localize the solid landmarkA novel indirect building localization technique based on a prominent solid landmark from a forward-looking infrared imagery is proposed to localize low, deeply buried, or carefully camouflaged buildings in dense urban areas. First, the widely used effective methods are applied to detect and localize the solid landmark. The building target is then precisely indirectly localized by perspective transformation according to the imaging parameters and the space constraint relations between the building target and the solid landmark. Experimental results demonstrate this technique can indirectly localize buildings in dense urban areas effectively..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 041003 (2011)
Optoelectronics
Compact triplexer in two-dimensional hexagonal lattice photonic crystals
Hongliang Ren, Jianping Ma, Hao Wen, Yali Qin, Zhefu Wu, Weisheng Hu, Chun Jiang, and Yaohui Jin
We design a compact triplexer based on two-dimensional (2D) hexagonal lattice photonic crystals (PCs). A folded directional coupler (FDC) is introduced in the triplexer beside the point-defect micro-cavities and line-defect waveguides. Because of the reflection feedback of the FDC, high channel drop efficiency can be rWe design a compact triplexer based on two-dimensional (2D) hexagonal lattice photonic crystals (PCs). A folded directional coupler (FDC) is introduced in the triplexer beside the point-defect micro-cavities and line-defect waveguides. Because of the reflection feedback of the FDC, high channel drop efficiency can be realized and a compact size with the order of micrometers can be maintained. The proposed device is analyzed using the plane wave expansion method, and its transmission characteristics are calculated using the finite-difference time-domain method. The footprint of the triplexer is about 12×9 μm, and its extinction ratios are less than –20 dB for 1310 nm, approximately –20 dB for 1490 nm, and under –40 dB for 1550 nm, making it a potentially essential device in future fiber-to-the-home networks..
Chinese Optics Letters
- Publication Date: Jul. 09, 2021
- Vol. 9, Issue 4, 042501 (2011)
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