We report a Tm-doped noise-like mode-locked(NLML)pulsed fiber laser with a compact linear cavity which consists of dual nonlinear optical loop mirrors(NOLMs).The design of dual-NOLM shows both exceptional compactness ...We report a Tm-doped noise-like mode-locked(NLML)pulsed fiber laser with a compact linear cavity which consists of dual nonlinear optical loop mirrors(NOLMs).The design of dual-NOLM shows both exceptional compactness in construction and distinct flexibility.In this laser,mode-locking can be realized through the nonlinear optical loop mirror technique.Stable noise-like mode-locked pulses with spectral bandwidth of 29.18 nm and pulse energy of 46 nJ are generated at a central wavelength of 1999.7 nm.Our results indicate that such a simple and inexpensive structure can pave the way for the development of generating supercontinuum with desirable performance.展开更多
The performance of an optical time domain reflectometer(OTDR) is significantly improved using spread spectrum technology. The concept of spread spectrum OTDR(SSOTDR) is proposed, the theoretical basis and simulation r...The performance of an optical time domain reflectometer(OTDR) is significantly improved using spread spectrum technology. The concept of spread spectrum OTDR(SSOTDR) is proposed, the theoretical basis and simulation results of the new method are given, and the problem of direct application of bipolar spread spectrum codes to OTDR and despreading in the optical domain are solved. The simulation results show the feasibility of the SSOTDR, which exhibits better dynamic range reported to date for a practical long-haul OTDR system without using conventional average technique.展开更多
Ge films were prepared at different deposition temperatures and ion source bias voltage using the electron beam evaporation.The infrared refractive index was obtained by spectral inversion.Results show that the refrac...Ge films were prepared at different deposition temperatures and ion source bias voltage using the electron beam evaporation.The infrared refractive index was obtained by spectral inversion.Results show that the refractive index becomes larger as the deposition temperature increases.The maximum refractive index at the wavelength of 4000 nm is 4.274 with the deposition temperatures of 210℃.The refractive index of film decreases first and then increases as the bias voltage increases.When the ion source bias voltage is 120 V,the refractive index of the film is the smallest.The difference in extinction coefficient of Ge films prepared by different process parameters is small.展开更多
In this paper, a novel method is proposed to characterize the operation-waveband angular resolution of the soft X-ray grazing incidence telescope.According to the method, the first is to restore the "geometric im...In this paper, a novel method is proposed to characterize the operation-waveband angular resolution of the soft X-ray grazing incidence telescope.According to the method, the first is to restore the "geometric image" by removing the aperture diffraction effect from the resolution testing target image measured at visible waveband.The second is to calculate the operation-waveband resolution testing target image by the convolution of "geometric image", diffraction point spread function and surface scattering point spread function.Finally, the operation-waveband(4.47 nm) angular resolution of 9.72" is calculated according to the operation-waveband resolution testing target image on axis.The method does not need to be performed in vacuum and to place the source away from the solar X-ray grazing incidence telescope, which greatly reduces the testing cost and improves the efficiency for the development of the soft X-ray grazing incidence telescope.展开更多
To Authors, Reviewers, Readers,We congratulate the 2019 new year to our authors, reviewers, readers, cooperators and all the friends, and give our most sincere thanks to you. In the coming year, we still strive to pro...To Authors, Reviewers, Readers,We congratulate the 2019 new year to our authors, reviewers, readers, cooperators and all the friends, and give our most sincere thanks to you. In the coming year, we still strive to provide strict and timely reviews for authors while bringing top quality letters for the researchers.展开更多
The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space ...The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects(target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10^(-5), which outperforms those of compared algorithms.展开更多
Based on the orbital angular momentum and pulse position modulation, we present a novel passive measurement-device-independent quantum key distribution(MDI-QKD) scheme with the two-mode source. Combining with the tigh...Based on the orbital angular momentum and pulse position modulation, we present a novel passive measurement-device-independent quantum key distribution(MDI-QKD) scheme with the two-mode source. Combining with the tight bounds of the yield and error rate of single-photon pairs given in our paper, we conduct performance analysis on the scheme with heralded single-photon source. The numerical simulations show that the performance of our scheme is significantly superior to the traditional MDI-QKD in the error rate, key generation rate and secure transmission distance, since the application of orbital angular momentum and pulse position modulation can exclude the basis-dependent flaw and increase the information content for each single photon. Moreover, the performance is improved with the rise of the frame length. Therefore, our scheme, without intensity modulation, avoids the source side channels and enhances the key generation rate. It has greatly utility value in the MDI-QKD setups.展开更多
The growth of Na_5Lu_9F_(32) single crystals doped with Cr^(3+)ions in 0.1 mol%,0.2 mol%and 0.5 mol%concentrations by Bridgman method was reported.The optical absorption and luminescence spectra decisively demonstrate...The growth of Na_5Lu_9F_(32) single crystals doped with Cr^(3+)ions in 0.1 mol%,0.2 mol%and 0.5 mol%concentrations by Bridgman method was reported.The optical absorption and luminescence spectra decisively demonstrate that the Cr dopant enters Na_5Lu_9F_(32) as Cr^(3+).Fluorescence emission at wavelengths of 418 nm,444 nm,653 nm and 678 nm can be observed under the excitation of 372 nm and the fluorescence lifetime at 418 nm was measured to be^10.31μs.The possible crystal sites for Cr^(3+)ions in Na_5Lu_9F_(32) single crystal were discussed,and the lattice parameter Dq,Racach parameters B and C were estimated.展开更多
In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) a...In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) are studied in this paper. The time-domain synchronization,frequency synchronization and channel equalization of receiver are analyzed and optimized by utilizing short and long training preamble. Moreover,field programmable gate array(FPGA) development board(Xilinx Kintex-7) and Verilog hardware description language are used to realize the design of proposed OFDM-VLC system. Simulation and experiment both verify the feasibility of the hardware designs of this system. The proposed OFDM-based VLC system can process signal in real-time,which can be used in actual VLC application systems.展开更多
Nano-hole patterned sapphire substrates(NHPSSs) were successfully prepared using a low-cost and high-efficiency approach, which is the laser interference lithography(LIL) combined with reactive ion etching(RIE) and in...Nano-hole patterned sapphire substrates(NHPSSs) were successfully prepared using a low-cost and high-efficiency approach, which is the laser interference lithography(LIL) combined with reactive ion etching(RIE) and inductively coupled plasma(ICP) techniques. Gallium nitride(Ga N)-based light emitting diode(LED) structure was grown on NHPSS by metal organic chemical vapor deposition(MOCVD). Photoluminescence(PL) measurement was conducted to compare the luminescence efficiency of the Ga N-based LED structure grown on NHPSS(NHPSS-LED) and that on unpatterned sapphire substrates(UPSS-LED). Electroluminescence(EL) measurement shows that the output power of NHPSS-LED is 2.3 times as high as that of UPSS-LED with an injection current of 150 m A. Both PL and EL results imply that NHPSS has an advantage in improving the crystalline quality of Ga N epilayer and light extraction efficiency of LEDs at the same time.展开更多
For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis rev...For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis reveal that the magnitude of responsive signal is increased by optical focusing,and the SNR is improved remarkably.These research results indicate that the optical focusing is an effective approach for improving SNR of LAPS.展开更多
Microstructure and misfit dislocation behavior in In_xGa_(1-x)As/InP heteroepitaxial materials grown by low pressure metal organic chemical vapor deposition(LP-MOCVD) were analyzed by high resolution transmission elec...Microstructure and misfit dislocation behavior in In_xGa_(1-x)As/InP heteroepitaxial materials grown by low pressure metal organic chemical vapor deposition(LP-MOCVD) were analyzed by high resolution transmission electron microscopy(HRTEM), scanning electron microscopy(SEM), atomic force microscopy(AFM), Raman spectroscopy and Hall effect measurements. To optimize the structure of In_(0.82)Ga_(0.18)As/InP heterostructure, the In_xGa_(1-x)As buffer layer was grown. The residual strain of the In_(0.82)Ga_(0.18)As epitaxial layer was calculated. Further, the periodic growth pattern of the misfit dislocation at the interface was discovered and verified. Then the effects of misfit dislocation on the surface morphology and microstructure of the material were studied. It is found that the misfit dislocation of high indium(In) content In_(0.82)Ga_(0.18)As epitaxial layer has significant influence on the carrier concentration.展开更多
A measurement-device-independent quantum key distribution(MDI-QKD) method with an air-water channel is researched. In this method, the underwater vehicle and satellite are the legitimate parties, and the third party i...A measurement-device-independent quantum key distribution(MDI-QKD) method with an air-water channel is researched. In this method, the underwater vehicle and satellite are the legitimate parties, and the third party is at the airwater interface in order to simplify the unilateral quantum channel to water or air. Considering the condition that both unilateral transmission distance and transmission loss coefficient are unequal, a perfect model of the asymmetric channel is built. The influence of asymmetric channel on system loss tolerance and secure transmission distance is analyzed. The simulation results show that with the increase of the channel's asymmetric degree, the system loss tolerance will descend, one transmission distance will be reduced while the other will be increased. When the asymmetric coefficient of channel is between 0.068 and 0.171, MDI-QKD can satisfy the demand of QKD with an air-water channel, namely the underwater transmission distance and atmospheric transmission distance are not less than 60 m and 12 km, respectively.展开更多
Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on t...Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of In As0.09Sb0.91 detectors is obviously extended to 11.5 μm, and that of In As0.05Sb0.95 detectors is 8.3 μm. At room temperature, the peak detectivity of Dλp* at wavelength of 6.8 μm and modulation frequency of 1 200 Hz is 1.08×109 cm·Hz1/2·W-1 for In As0.09Sb0.91 photoconductors, the detectivity D* at wavelength of 9 μm is 7.56×108 cm·Hz1/2·W-1, and that at 11 μm is 3.92×108 cm·Hz1/2·W-1. The detectivity of In As0.09Sb0.91 detectors at the wavelengths longer than 9 μm is about one order of magnitude higher than that of In As0.05Sb0.95 detectors, which rises from the increase of arsenic(As) composition in In As0.09Sb0.91 materials.展开更多
For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) r...For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) radiation.An effective energy transfer from Sm^(3+) to Eu^(3+) is proved.The commission international de I'Eclairage(CIE) chromaticity coordinates of BEP:Sm^(3+) locate at red region.When the environment temperature is 150℃,the emission intensity of BEP:0.10Sm^(3+) is decreased to 76%of the initial one at room temperature,and the activation energy is calculated to be0.164 eV,which can prove the good thermal stability of BEP:Sm^(3+).The results indicate that BEP:Sm^(3+) may have potential applications in white light emitting diodes(LEDs).展开更多
A type of spatial modulating micro Fourier transform spectrometer(FTS) based on micro multi-step mirrors(MMSMs) is designed and manufactured in this paper.The interference system is based on Michelson interferometer,u...A type of spatial modulating micro Fourier transform spectrometer(FTS) based on micro multi-step mirrors(MMSMs) is designed and manufactured in this paper.The interference system is based on Michelson interferometer,using two MMSMs instead of plane mirrors in two arms.The recovered spectrum is simulated with different distances between MMSMs and the detector,and the influence of diffraction on the recovered spectrum is analyzed.The edge-enlarging method for the MMSMs is proposed to eliminate edge noise,and the influence of surface roughness of MMSMs on the recovered spectrum is also analyzed.Moreover,the way of manufacturing the MMSMs is investigated.展开更多
Three-dimensional(3D) modeling of medical images is a critical part of surgical simulation. In this paper, we focus on the magnetic resonance(MR) images denoising for brain modeling reconstruction, and exploit a pract...Three-dimensional(3D) modeling of medical images is a critical part of surgical simulation. In this paper, we focus on the magnetic resonance(MR) images denoising for brain modeling reconstruction, and exploit a practical solution. We attempt to remove the noise existing in the MR imaging signal and preserve the image characteristics. A wavelet-based adaptive curve shrinkage function is presented in spherical coordinates system. The comparative experiments show that the denoising method can preserve better image details and enhance the coefficients of contours. Using these denoised images, the brain 3D visualization is given through surface triangle mesh model, which demonstrates the effectiveness of the proposed method.展开更多
An improved multiplier-free feed-forward carrier phase estimation algorithm is proposed for dual-polarization quad-rature-phase-shift-keying (DP-QPSK) with coherent detection. The bit error rate (BER) performance, blo...An improved multiplier-free feed-forward carrier phase estimation algorithm is proposed for dual-polarization quad-rature-phase-shift-keying (DP-QPSK) with coherent detection. The bit error rate (BER) performance, block length effect and linewidth tolerance of the proposed algorithm are evaluated for a 112 Gbit/s DP-QPSK system. A linewidth symbol duration product of 2.9×10-4 is demonstrated for 1 dB optical signal-to-noise-ratio (OSNR) penalty at BER of 10-3 for the proposed algorithm. The hardware complexity of the proposed multiplier-free algorithm is demonstrated to be much lower than that of the 4th power algorithm.展开更多
The absorption enhancements of silicon layer in silicon solar cells with three kinds of Ag nanoparticles including sphere,cylinder and cuboid are studied by the finite difference time domain(FDTD)method,respectively.T...The absorption enhancements of silicon layer in silicon solar cells with three kinds of Ag nanoparticles including sphere,cylinder and cuboid are studied by the finite difference time domain(FDTD)method,respectively.The results show that the light absorption of silicon is significantly improved due to the localized surface plasmon(LSP)resonance.The relations of the absorption enhancement with the parameters of nanoparticles are thoroughly analyzed.The optimal absorption enhancement can be achieved by adjusting the relevant parameters.Among the three types of Ag nanoparticles,i.e.,sphere,cylinder and cuboid,the silicon with the cubical Ag nanopaticles shows the most efficient absorption enhancement at optimal conditions,its maximum absorption enhancement factor is 1.35,and that with the spherical Ag nanopaticles gets the lowest absorption enhancement.The work is useful for the further theoretical study and design for the plasmonic thin-film solar cell.展开更多
基金supported by the Nature Science Foundation of Chongqing(No.cstc2018jcyjAX0585)。
文摘We report a Tm-doped noise-like mode-locked(NLML)pulsed fiber laser with a compact linear cavity which consists of dual nonlinear optical loop mirrors(NOLMs).The design of dual-NOLM shows both exceptional compactness in construction and distinct flexibility.In this laser,mode-locking can be realized through the nonlinear optical loop mirror technique.Stable noise-like mode-locked pulses with spectral bandwidth of 29.18 nm and pulse energy of 46 nJ are generated at a central wavelength of 1999.7 nm.Our results indicate that such a simple and inexpensive structure can pave the way for the development of generating supercontinuum with desirable performance.
基金supported by the National Natural Science Foundation of China (No.61735011)the Science and Technology Research Project of Hebei University (No.QN2017141)the Key Research and Development Program of Hebei Province (No.19251703D)。
文摘The performance of an optical time domain reflectometer(OTDR) is significantly improved using spread spectrum technology. The concept of spread spectrum OTDR(SSOTDR) is proposed, the theoretical basis and simulation results of the new method are given, and the problem of direct application of bipolar spread spectrum codes to OTDR and despreading in the optical domain are solved. The simulation results show the feasibility of the SSOTDR, which exhibits better dynamic range reported to date for a practical long-haul OTDR system without using conventional average technique.
基金supported by the Key Laboratory Fund of Lanzhou Institute of Physics(No.9140C540303130C54005)。
文摘Ge films were prepared at different deposition temperatures and ion source bias voltage using the electron beam evaporation.The infrared refractive index was obtained by spectral inversion.Results show that the refractive index becomes larger as the deposition temperature increases.The maximum refractive index at the wavelength of 4000 nm is 4.274 with the deposition temperatures of 210℃.The refractive index of film decreases first and then increases as the bias voltage increases.When the ion source bias voltage is 120 V,the refractive index of the film is the smallest.The difference in extinction coefficient of Ge films prepared by different process parameters is small.
基金supported by the National Natural Science Foundation of China(No.U1631117)
文摘In this paper, a novel method is proposed to characterize the operation-waveband angular resolution of the soft X-ray grazing incidence telescope.According to the method, the first is to restore the "geometric image" by removing the aperture diffraction effect from the resolution testing target image measured at visible waveband.The second is to calculate the operation-waveband resolution testing target image by the convolution of "geometric image", diffraction point spread function and surface scattering point spread function.Finally, the operation-waveband(4.47 nm) angular resolution of 9.72" is calculated according to the operation-waveband resolution testing target image on axis.The method does not need to be performed in vacuum and to place the source away from the solar X-ray grazing incidence telescope, which greatly reduces the testing cost and improves the efficiency for the development of the soft X-ray grazing incidence telescope.
文摘To Authors, Reviewers, Readers,We congratulate the 2019 new year to our authors, reviewers, readers, cooperators and all the friends, and give our most sincere thanks to you. In the coming year, we still strive to provide strict and timely reviews for authors while bringing top quality letters for the researchers.
基金supported by the National High Technology Research and Development Program of China(No.2011AAXXX2035)the Third Phase of Innovative Engineering Projects Foundation of the Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(No.065X32CN60)
文摘The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects(target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10^(-5), which outperforms those of compared algorithms.
基金supported by the National Natural Science Foundation of China(No.61302099)
文摘Based on the orbital angular momentum and pulse position modulation, we present a novel passive measurement-device-independent quantum key distribution(MDI-QKD) scheme with the two-mode source. Combining with the tight bounds of the yield and error rate of single-photon pairs given in our paper, we conduct performance analysis on the scheme with heralded single-photon source. The numerical simulations show that the performance of our scheme is significantly superior to the traditional MDI-QKD in the error rate, key generation rate and secure transmission distance, since the application of orbital angular momentum and pulse position modulation can exclude the basis-dependent flaw and increase the information content for each single photon. Moreover, the performance is improved with the rise of the frame length. Therefore, our scheme, without intensity modulation, avoids the source side channels and enhances the key generation rate. It has greatly utility value in the MDI-QKD setups.
基金supported by the National Natural Science Foundation of China(Nos.51772159,51472125,11504188 and U1504626)the Natural Science Foundation of Zhejiang Province(No.LZ17E020001)K.C.Wong Magna Fund in Ningbo University
文摘The growth of Na_5Lu_9F_(32) single crystals doped with Cr^(3+)ions in 0.1 mol%,0.2 mol%and 0.5 mol%concentrations by Bridgman method was reported.The optical absorption and luminescence spectra decisively demonstrate that the Cr dopant enters Na_5Lu_9F_(32) as Cr^(3+).Fluorescence emission at wavelengths of 418 nm,444 nm,653 nm and 678 nm can be observed under the excitation of 372 nm and the fluorescence lifetime at 418 nm was measured to be^10.31μs.The possible crystal sites for Cr^(3+)ions in Na_5Lu_9F_(32) single crystal were discussed,and the lattice parameter Dq,Racach parameters B and C were estimated.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2015AA033303)the National Key Basic Research Program of China(973 program)(No.2013CB329204)+1 种基金the National Nature Science Foundation of China(Nos.61178051,61321063 and 61335010)the Science and Technology Project of Guangdong Province in China(No.2014B010120004)
文摘In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) are studied in this paper. The time-domain synchronization,frequency synchronization and channel equalization of receiver are analyzed and optimized by utilizing short and long training preamble. Moreover,field programmable gate array(FPGA) development board(Xilinx Kintex-7) and Verilog hardware description language are used to realize the design of proposed OFDM-VLC system. Simulation and experiment both verify the feasibility of the hardware designs of this system. The proposed OFDM-based VLC system can process signal in real-time,which can be used in actual VLC application systems.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of China(No.2012YQ17000406)the Foshan-CAS Cooperated Projects(No.2012A01)
文摘Nano-hole patterned sapphire substrates(NHPSSs) were successfully prepared using a low-cost and high-efficiency approach, which is the laser interference lithography(LIL) combined with reactive ion etching(RIE) and inductively coupled plasma(ICP) techniques. Gallium nitride(Ga N)-based light emitting diode(LED) structure was grown on NHPSS by metal organic chemical vapor deposition(MOCVD). Photoluminescence(PL) measurement was conducted to compare the luminescence efficiency of the Ga N-based LED structure grown on NHPSS(NHPSS-LED) and that on unpatterned sapphire substrates(UPSS-LED). Electroluminescence(EL) measurement shows that the output power of NHPSS-LED is 2.3 times as high as that of UPSS-LED with an injection current of 150 m A. Both PL and EL results imply that NHPSS has an advantage in improving the crystalline quality of Ga N epilayer and light extraction efficiency of LEDs at the same time.
基金supported by the National Natural Science Foundation of China(No.61265006)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20126102110031)the Scientific Research Fund of Guangxi Education Department(No.2013YB089)
文摘For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis reveal that the magnitude of responsive signal is increased by optical focusing,and the SNR is improved remarkably.These research results indicate that the optical focusing is an effective approach for improving SNR of LAPS.
基金supported by the National Key Basic Research Program of China(No.2012CB619200)the National Natural Science Foundation of China(No.61474053)+1 种基金the State Key Laboratory for Mechanical Behavior of Materials of Xi'an Jiaotong University(No.20161806)the Natural Science Basic Research Open Foundation of the Key Lab of Automobile Materials,Ministry of Education,Jilin University(No.1018320144001)
文摘Microstructure and misfit dislocation behavior in In_xGa_(1-x)As/InP heteroepitaxial materials grown by low pressure metal organic chemical vapor deposition(LP-MOCVD) were analyzed by high resolution transmission electron microscopy(HRTEM), scanning electron microscopy(SEM), atomic force microscopy(AFM), Raman spectroscopy and Hall effect measurements. To optimize the structure of In_(0.82)Ga_(0.18)As/InP heterostructure, the In_xGa_(1-x)As buffer layer was grown. The residual strain of the In_(0.82)Ga_(0.18)As epitaxial layer was calculated. Further, the periodic growth pattern of the misfit dislocation at the interface was discovered and verified. Then the effects of misfit dislocation on the surface morphology and microstructure of the material were studied. It is found that the misfit dislocation of high indium(In) content In_(0.82)Ga_(0.18)As epitaxial layer has significant influence on the carrier concentration.
基金supported by the National Natural Science Foundation of China(No.61302099)
文摘A measurement-device-independent quantum key distribution(MDI-QKD) method with an air-water channel is researched. In this method, the underwater vehicle and satellite are the legitimate parties, and the third party is at the airwater interface in order to simplify the unilateral quantum channel to water or air. Considering the condition that both unilateral transmission distance and transmission loss coefficient are unequal, a perfect model of the asymmetric channel is built. The influence of asymmetric channel on system loss tolerance and secure transmission distance is analyzed. The simulation results show that with the increase of the channel's asymmetric degree, the system loss tolerance will descend, one transmission distance will be reduced while the other will be increased. When the asymmetric coefficient of channel is between 0.068 and 0.171, MDI-QKD can satisfy the demand of QKD with an air-water channel, namely the underwater transmission distance and atmospheric transmission distance are not less than 60 m and 12 km, respectively.
基金supported by the Fundamental Research Funds for the Central Universities in China
文摘Uncooled In As Sb photoconductors were fabricated. The photoconductors were based on In As0.05Sb0.95 and In As0.09Sb0.91 thick epilayers grown on In As substrates by melt epitaxy(ME). Ge immersion lenses were set on the photoconductors. The cutoff wavelength of In As0.09Sb0.91 detectors is obviously extended to 11.5 μm, and that of In As0.05Sb0.95 detectors is 8.3 μm. At room temperature, the peak detectivity of Dλp* at wavelength of 6.8 μm and modulation frequency of 1 200 Hz is 1.08×109 cm·Hz1/2·W-1 for In As0.09Sb0.91 photoconductors, the detectivity D* at wavelength of 9 μm is 7.56×108 cm·Hz1/2·W-1, and that at 11 μm is 3.92×108 cm·Hz1/2·W-1. The detectivity of In As0.09Sb0.91 detectors at the wavelengths longer than 9 μm is about one order of magnitude higher than that of In As0.05Sb0.95 detectors, which rises from the increase of arsenic(As) composition in In As0.09Sb0.91 materials.
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province in China(Nos.A2014201035 and E2014201037)+1 种基金the Education Office Research Foundation of Hebei Province in China(Nos.ZD2014036 and QN2014085)the College Students Innovation and Entrepreneurship of Hebei University in China(Nos.2014041 and 2015063)
文摘For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) radiation.An effective energy transfer from Sm^(3+) to Eu^(3+) is proved.The commission international de I'Eclairage(CIE) chromaticity coordinates of BEP:Sm^(3+) locate at red region.When the environment temperature is 150℃,the emission intensity of BEP:0.10Sm^(3+) is decreased to 76%of the initial one at room temperature,and the activation energy is calculated to be0.164 eV,which can prove the good thermal stability of BEP:Sm^(3+).The results indicate that BEP:Sm^(3+) may have potential applications in white light emitting diodes(LEDs).
基金supported by the National Natural Science Foundation of China(Nos.61027010 and 61376122)Jilin Province Science and Technology Development Plan(Nos.201205025 and 20130206010GX)+1 种基金Changchun Science and Technology Plan(No.11DJ03)State Key Laboratory of Applied Optics Own Funds
文摘A type of spatial modulating micro Fourier transform spectrometer(FTS) based on micro multi-step mirrors(MMSMs) is designed and manufactured in this paper.The interference system is based on Michelson interferometer,using two MMSMs instead of plane mirrors in two arms.The recovered spectrum is simulated with different distances between MMSMs and the detector,and the influence of diffraction on the recovered spectrum is analyzed.The edge-enlarging method for the MMSMs is proposed to eliminate edge noise,and the influence of surface roughness of MMSMs on the recovered spectrum is also analyzed.Moreover,the way of manufacturing the MMSMs is investigated.
基金supported by the National Natural Science Foundation of China(No.61202169)the Tianjin Key Natural Science Foundation(No.13JCZDJC34600)+1 种基金the China Scholarship Council(CSC)Foundation(No.201308120010)the Training Plan of Tianjin University Innovation Team(No.TD12-5016)
文摘Three-dimensional(3D) modeling of medical images is a critical part of surgical simulation. In this paper, we focus on the magnetic resonance(MR) images denoising for brain modeling reconstruction, and exploit a practical solution. We attempt to remove the noise existing in the MR imaging signal and preserve the image characteristics. A wavelet-based adaptive curve shrinkage function is presented in spherical coordinates system. The comparative experiments show that the denoising method can preserve better image details and enhance the coefficients of contours. Using these denoised images, the brain 3D visualization is given through surface triangle mesh model, which demonstrates the effectiveness of the proposed method.
基金the National Natural Science Foundation of China (No.61275052)the National High-Tech Research and Development Program of China (No.2007AA01Z258)+2 种基金the Fundamental Research Funds for the Central Universities (No.2009YJS005)the Major State Basic Research Development Program of China (No.2010CB328206)the Beijing Nova Program (No.2008A026)
文摘An improved multiplier-free feed-forward carrier phase estimation algorithm is proposed for dual-polarization quad-rature-phase-shift-keying (DP-QPSK) with coherent detection. The bit error rate (BER) performance, block length effect and linewidth tolerance of the proposed algorithm are evaluated for a 112 Gbit/s DP-QPSK system. A linewidth symbol duration product of 2.9×10-4 is demonstrated for 1 dB optical signal-to-noise-ratio (OSNR) penalty at BER of 10-3 for the proposed algorithm. The hardware complexity of the proposed multiplier-free algorithm is demonstrated to be much lower than that of the 4th power algorithm.
基金supported by the International Scientific and Technological Cooperation Projects of Guizhou Province in China(No.[2011]7035)
文摘The absorption enhancements of silicon layer in silicon solar cells with three kinds of Ag nanoparticles including sphere,cylinder and cuboid are studied by the finite difference time domain(FDTD)method,respectively.The results show that the light absorption of silicon is significantly improved due to the localized surface plasmon(LSP)resonance.The relations of the absorption enhancement with the parameters of nanoparticles are thoroughly analyzed.The optimal absorption enhancement can be achieved by adjusting the relevant parameters.Among the three types of Ag nanoparticles,i.e.,sphere,cylinder and cuboid,the silicon with the cubical Ag nanopaticles shows the most efficient absorption enhancement at optimal conditions,its maximum absorption enhancement factor is 1.35,and that with the spherical Ag nanopaticles gets the lowest absorption enhancement.The work is useful for the further theoretical study and design for the plasmonic thin-film solar cell.
