Journals >Frontiers of Optoelectronics
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2008
Volume: 1 Issue 3
28 Article(s)
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Research Article
Applications of scanning femtosecond laser-induced ionization microscopy in biological imaging
Youbo ZHAO, Yanmei LIANG, and Xiaonong ZHU
The applicability and potential advantages of femtosecond laser-induced ionization microscopy in examining biological samples are demonstrated. Highresolution section images of the inner structures and the topographical surface profiles of a piece of unstained onion skin and a human oral epithelium specimen are obtaineThe applicability and potential advantages of femtosecond laser-induced ionization microscopy in examining biological samples are demonstrated. Highresolution section images of the inner structures and the topographical surface profiles of a piece of unstained onion skin and a human oral epithelium specimen are obtained by collecting the plasma emission signals generated either inside the samples or from air in the vicinity. It is concluded that the high material discrimination capability and the minimum damage effect give this laser-induced ionization imaging technique great potentials in the area of biological imaging and medical analyses..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 201 (2008)
Analysis of flash lamp structure using Monte Carlo photon tracing method
Liefeng ZHAO, Huajun FENG, and Zhihai XU
By analyzing the flash lamp structure, better illumination distributions in the lamp’s field of view can be obtained. Instead of geometrical optical approaches, the Monte Carlo photon tracing method was used here to trace the photon tracks in a three-dimensional space. The models of elemental structures in a camera flaBy analyzing the flash lamp structure, better illumination distributions in the lamp’s field of view can be obtained. Instead of geometrical optical approaches, the Monte Carlo photon tracing method was used here to trace the photon tracks in a three-dimensional space. The models of elemental structures in a camera flash lamp, such as the flash tube, reflector and focus lens, were set up by introducing the cosinusoidal random number and other mathematical methods. Initially, the single photon was traced in the flash lamp by using the Monte Carlo method to simulate various photon tracks. A large sum of photons was then generated to simulate the real situation in the flash lamp. Finally, a group of structural parameters was applied to verify the simulative computer program. The output light intensity distributions at different angles of view in the orthogonal directions meet the ISO standards and are very close to the measured ones. Hence, the Monte Carlo photon tracing method in the design of flash lamps has been proven to be applicable and useful..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 205 (2008)
Micro Fabry Perot light modulator for flat panel display
Jiyong SUN, Shanglian HUANG, Jie ZHANG, Yi QIN, and Xuming SUN
A new type of Fabry Perot light modulator for displays based on micro-electro-mechanical system technology is proposed. Multiple beam interference theory is used to design the modulator and analyze its characteristics. If Fabry Perot cavity length is one-quarter of the incident wavelength, the transmitted light is blocA new type of Fabry Perot light modulator for displays based on micro-electro-mechanical system technology is proposed. Multiple beam interference theory is used to design the modulator and analyze its characteristics. If Fabry Perot cavity length is one-quarter of the incident wavelength, the transmitted light is blocked by the modulator, and the modulator, which is illuminated from its backside, appears black. If the Fabry Perot cavity length is 0 or one-half of the incident wavelength, light may transmit the Fabry Perot modulator from its backside, and the modulator appears bright. Hence, the modulator may be used for flat panel displays. In this paper one Fabry Perot light modulator based on surface micromachining technology is introduced. The designed modulator has a contrast ratio of 150 and can theoretically be driven by a voltage of 2.4 V..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 210 (2008)
High efficient and narrow linewidth fiber laser based on fiber grating Fabry-Perot cavity
Bo WU, Yongzhi LIU, Qianshu ZHANG, Huimin YUE, and Zhiyong DAI
A high Er3+-doped narrow linewidth fiber laser based on fiber Bragg grating Fabry-Perot cavity was demonstrated. The spatial hole burning effect was restrained by a fiber Faraday rotator. Two short fiber Bragg grating Fabry-Perot cavities as narrow bandwidth filters discriminated and selected laser longitudinal modes eA high Er3+-doped narrow linewidth fiber laser based on fiber Bragg grating Fabry-Perot cavity was demonstrated. The spatial hole burning effect was restrained by a fiber Faraday rotator. Two short fiber Bragg grating Fabry-Perot cavities as narrow bandwidth filters discriminated and selected laser longitudinal modes efficiently. A stable single-frequency 1534.83 nm laser was acquired. Pumped by two 976 nm laser diodes and twoended output, the fiber laser exhibited a 12 mW threshold. Total 39.5 mW output power and one end 22 mW output power were obtained at the maximum 145 mW pump power. Optical-optical efficiency was 27% and slope efficiency was 29.7%. The output power seemed to be saturated when pump power increased. The 3 dB linewidth of the laser was less than 7.5 kHz, measured by the delayed self-heterodyne method with 15 km monomode fiber. The high power narrow linewidth fiber laser can be used in high resolution fiber sensor systems..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 215 (2008)
2500 km-10 Gbps RZ transmission system based on dispersion compensation CFBGs without electric regenerator
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristics of chirped fiber Bragg gratings (CFBGs) are optimized so that the ripple coefficient of the power reflectivity spectrum and group time delay are less than 1 dB and |±15| ps, group delay is about 2600 ps/nm, polarization module dispersion is very small, PMD,2 ps, 23 dB bandwidth is about 0.35 nmThe characteristics of chirped fiber Bragg gratings (CFBGs) are optimized so that the ripple coefficient of the power reflectivity spectrum and group time delay are less than 1 dB and |±15| ps, group delay is about 2600 ps/nm, polarization module dispersion is very small, PMD,2 ps, 23 dB bandwidth is about 0.35 nm, and insertion loss is about 4-5 dBm. Using dispersion compensation CFBG, a 2500 km-10 Gbps RZ optical signal transmission system on G.652 fiber was successfully demonstrated without an electric regenerator by optimizing dispersion management and loss management. The RZ optical signal was generated through a two-stage modulation method. At 2081 km, the power penalty of transmission is about 3 dB (conditions: RZ signal, BER510212, PRBS5102321); At 2560 km, the power penalty is about 5 dB. It is superior to the system using NRZ under the same conditions..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 219 (2008)
Temperature sensing capacity of fiber Bragg grating at liquid nitrogen temperature
Guoli CAI, and Wei JIAN
According to the temperature sensing model of the fiber Bragg grating (FBG), a theoretical method of temperature sensing capacity of FBG is proposed. Based on the temperature sensing model of FBG, a temperature sensing experiment was completed at liquid nitrogen temperature (2196uC). The theoretical and experimental reAccording to the temperature sensing model of the fiber Bragg grating (FBG), a theoretical method of temperature sensing capacity of FBG is proposed. Based on the temperature sensing model of FBG, a temperature sensing experiment was completed at liquid nitrogen temperature (2196uC). The theoretical and experimental results were compared and analyzed, which show that at liquid nitrogen temperature or in a large-scope temperature sensing, the relationship between thermal variation DT and relative shift of reflected center wavelength DlB/lB of FBG is nonlinear and conic multinomial..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 223 (2008)
A novel weight measurement method based on birefringence in fiber Bragg gratings
Yong ZHAO, Huawei ZHAO, and Jian YANG
Unlike the usual wavelength modulation principle of fiber Bragg grating (FBG) sensors, a novel weight sensor based on birefringence in FBG is proposed in this paper. The creation of the birefringence is based on the different stresses of the two orthogonal directions in the fiber core cross-section. If weight is applieUnlike the usual wavelength modulation principle of fiber Bragg grating (FBG) sensors, a novel weight sensor based on birefringence in FBG is proposed in this paper. The creation of the birefringence is based on the different stresses of the two orthogonal directions in the fiber core cross-section. If weight is applied on an FBG in the radial direction, two reflection spectra with different polarization states which can be observed by an optical spectrum analyzer will occur. An experimental prototype is set up and the measurement principle is described in this paper. Preliminary experimental results indicate that the proposed measurement method is very suitable for the application of heavy weight measurement in the range of 20 tons, especially for vehicle load monitoring in highway charge-by-weight systems. The sensitivity of weight measurement is be estimated to be about 5 kg..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 226 (2008)
Four-core fiber-based bending sensor
Shigang ZHAO, Xue WANG, and Libo YUAN
A novel four-core fiber-based bending sensor has been proposed. The four-core fiber is used as the sensing element, the four cores of the fiber act as a four-beam interferometer, and the far-field interferogram grids with periodical distributions are formed on the fiber output end. Since the phase difference is a functA novel four-core fiber-based bending sensor has been proposed. The four-core fiber is used as the sensing element, the four cores of the fiber act as a four-beam interferometer, and the far-field interferogram grids with periodical distributions are formed on the fiber output end. Since the phase difference is a function of the radius of curvature, the change of the radius of curvature shifts the far-field interferometric grid pattern. A low-coherence laser diode with wavelength of 650 nm is adopted to illuminate the fiber, and the interferogram pattern in the farfield is recorded by a CCD camera. The relationship between the far-field grid pattern intensity distribution and the radius of curvature is established theoretically and confirmed experimentally..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 231 (2008)
Laser detection by electronic instead of optical heterodyne using a two-frequency laser
Lei LI, Changming ZHAO, and Suhui YANG
Alaser ranging system using a two-frequency laser is demonstrated, and the lidar-radar concept is introduced. A laser beamcarrying 100 MHz radio frequency is obtained by a monolithic nonplanar ring single-frequency oscillator and an acousto-optical modulator, which is used as the light source of the two-frequency detecAlaser ranging system using a two-frequency laser is demonstrated, and the lidar-radar concept is introduced. A laser beamcarrying 100 MHz radio frequency is obtained by a monolithic nonplanar ring single-frequency oscillator and an acousto-optical modulator, which is used as the light source of the two-frequency detecting experimental setup. With the optical transmitting and collecting system, the displacement information of a target mounted on a motorized translation stage is achieved. In signal processing, the displacement is obtained by calculating the phase difference between the reference and detection signals executed by a radio-frequency lock-in amplifier. The ranging system turns the optical heterodyne into an electronic demodulation, and the repetition error is less than 3%. The system takes advantage of the signal processing technologies of radar, and meanwhile maintains the advantages of laser detection..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 237 (2008)
Small particle detection method based on laser feedback
Guoqiang SUN, Jihong ZHENG, Gang ZHENG, and Songlin ZHUANG
In order to overcome the shortcomings of traditional particle measurement, a new method for the detection of small and single particles through laser feedback phenomenon is presented. This method is based on the laser feedback caused by radiation scattered back from a moving particle in the external cavity of the laserIn order to overcome the shortcomings of traditional particle measurement, a new method for the detection of small and single particles through laser feedback phenomenon is presented. This method is based on the laser feedback caused by radiation scattered back from a moving particle in the external cavity of the laser. The parameters of the single particle, such as the diameter, velocity, and quantity, can be measured and calculated from the change in output laser power. In the experiment, the confocal external cavity composed of a concave reflector and a positive lens is designed. This device is able to obtain the corresponding variety curve of standard particles passing through the confocal area, and then the parameters of the particles can be measured and calculated by combining the experimental data and standard curves. Experimental results show that this method is an easily operated and reliable way for particle detection. The measurement ranges from 0.2 to 2000 mm, resolution is 0.2 mm, and measurement error is within 2%. This device may have wide application in areas such as atmosphere particle detection and calibration of a single particle producer..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 241 (2008)
Analyses and calculations of noise in optical coherence tomography systems
Xiaonong ZHU, Yanmei LIANG, Youxin MAO, Yaqing JIA, Yiheng LIU, and Guoguang MU
Significant progress has been made in the study of optical coherence tomography (OCT) — a non-invasive, high resolution, and in vivo diagnostic method for medical imaging applications. In this paper, the principles of noise analyses for OCT systems have been described. Comparisons are made of signal-to-noise ratios forSignificant progress has been made in the study of optical coherence tomography (OCT) — a non-invasive, high resolution, and in vivo diagnostic method for medical imaging applications. In this paper, the principles of noise analyses for OCT systems have been described. Comparisons are made of signal-to-noise ratios for both balanced and unbalanced detection schemes under the ideal no-stray light situation as well as the non-ideal situation where residual reflections and scatterings are presented. Numerical examples of noise calculation accompanied by detailed comparison of the main characteristics of both time-domain and frequency-domain OCT systems are also presented. It is shown that a larger dynamic range can be achieved for a Fourier-domain OCT system even under the circumstances of high-speed image acquisition. The main results presented in this paper should be useful for the development of high performance OCT systems..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 247 (2008)
Temperature dependence of photoluminescence of QD arrays
Guoliang LIU, Jianghong YAO, Jingjun XU, and Zhanguo WANG
It is essentially important to understand the temperature dependence of the photoluminescence of multimodal quantum dot (QD) arrays for the realization of efficient photonic devices. In this paper, the dynamics processes of different density multimodal QD arrays were fitted by using the rate equation model. It is shownIt is essentially important to understand the temperature dependence of the photoluminescence of multimodal quantum dot (QD) arrays for the realization of efficient photonic devices. In this paper, the dynamics processes of different density multimodal QD arrays were fitted by using the rate equation model. It is shown that, in high density QD arrays, the intensity of photoluminescence of different QD families has different temperature dependence, and the intensity of photoluminescence is quenched as the temperature increases in low density QD arrays. In high density QD arrays, as the temperature increases, the carriers will be thermally excited into the wetting layer from QDs, and then some of them will be recaptured by the big scale QDs; carrier coupling takes place between the different QD families, while in low density QD arrays, the carrier transfer between different QD families will be limited. Temperature dependence of the maximum of the ratio of photoluminescence intensity of different QD families strongly depends on the difference of thermal activation energies..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 258 (2008)
A genetic algorithm used in a 61-element adaptive optical system
Ping YANG, Bing XU, Wenhan JIANG, and Shanqiu CHEN
To correct the phase aberrations in a wavefront, a wavefront sensorless adaptive optical (AO) system is set up. A real-number encoding Gaussian mutation genetic algorithm (GA) that is adopted to control a 61-element deformable mirror (DM) is presented. This GA uses the light intensity behind a pinhole on the focal planTo correct the phase aberrations in a wavefront, a wavefront sensorless adaptive optical (AO) system is set up. A real-number encoding Gaussian mutation genetic algorithm (GA) that is adopted to control a 61-element deformable mirror (DM) is presented. This GA uses the light intensity behind a pinhole on the focal plane as the objective function to optimize, and therefore to omit the procedure of measuring the phase aberrations in the laser wavefront by a wavefront sensor. Phase aberrations generated by the DM are brought to an ideal incident wavefront. Several correction simulations have been accomplished. The simulation results show that the genetic algorithm is capable of finding the optimum DM shape to correct the phase aberrations. After the phase aberrations of the wavefront have been corrected by GA, the peak light intensity on the focal plane can be improved at most by a factor of 30, and the encircled energy Strehl ratio can be increased ultimately to 0.96 from 0.032. It is also found that the convergence and stability of the 61 voltages on the DM is quite well. The simulation results prove that the genetic algorithm can be used in AO systems effectively..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 263 (2008)
Optical synthetic aperture circle-array optimization based on genetic algorithm
Yuntao HE, Yuesong JIANG, and Guangda LIU
An optimization model of circle array was set up from the basic optical synthetic aperture imaging principle. The circle array was optimized by adopting a genetic algorithm with an improved real coding method coding the location of sub-apertures. The measure function was designed based on maximizing the distances betweAn optimization model of circle array was set up from the basic optical synthetic aperture imaging principle. The circle array was optimized by adopting a genetic algorithm with an improved real coding method coding the location of sub-apertures. The measure function was designed based on maximizing the distances between u-v coverage dots and minimizing the redundant array. The point spread function, optical transfer function and diffractive imaging were analyzed with the circle array synthetic aperture imaging system. The optimized result of 8 to 16 sub-apertures on a circle array was obtained, and they were compared to the results achieved through simulated annealing algorithm. Using the emulator program, the point spread function was analyzed and contrasted to that of a uniform circle array. Results show that the real coding genetic algorithm can resolve the array optimization well, cost less time and get a better optimization compared with the simulated annealing algorithm..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 268 (2008)
Daytime observation technology of a lidar using an atomic filter
Xuewu CHENG, Shunsheng GONG, Faquan LI, Yang DAI, Juan SONG, Jiamin WANG, and Fengyan LI
Based on the dual-wavelength high altitude detecting lidar we developed, daytime observation capability was realized in its sodium fluorescence channel by employing a Na (sodium) atomic filter and other relevant technologies. Because of the very narrow passband and very high out-of-band suppression of the Na atomic filBased on the dual-wavelength high altitude detecting lidar we developed, daytime observation capability was realized in its sodium fluorescence channel by employing a Na (sodium) atomic filter and other relevant technologies. Because of the very narrow passband and very high out-of-band suppression of the Na atomic filter, the lidar echo at an 80-110 km altitude can be obtained even at noontime when background light from the sun is very strong. The capability for a 24-h continuous observation of the lidar system has been demonstrated by the preliminary observation result. This development makes the constant detection and investigation of high altitude atmosphere over the country possible..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 274 (2008)
A portable functional imaging instrument for psychology research based on near-infrared spectroscopy
Xiaohua LV, Yi ZHENG, Ting LI, Zhongxing ZHANG, and Hui GONG
To aid psychology researches on the function of the prefrontal cortex, a 16-channel brain functional imaging instrument based on near-infrared spectroscopy is developed. The probe of the instrument, covering a detection area of 15 cm64.4 cm of the prefrontal cortex, is made flexible and is easy to fix to the forehead. To aid psychology researches on the function of the prefrontal cortex, a 16-channel brain functional imaging instrument based on near-infrared spectroscopy is developed. The probe of the instrument, covering a detection area of 15 cm64.4 cm of the prefrontal cortex, is made flexible and is easy to fix to the forehead. By employing multi-wavelength LEDs as light sources, using integrated detectors and choosing a USB-interface-based data acquisition device, the whole system is portable and convenient to use, which is good for psychological experiments. The system software is developed using Visual C++ 6.0, which controls the imaging process, measurement data plotting and storage. The maximal temporal resolution is about 100 ms. Noise and long-term drift test are given. The Valsalva maneuver experiment is used to validate the reliability of the instrument for monitoring hemodynamic changes..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 279 (2008)
A new automatic exposure algorithm for video cameras using luminance histogram
Haitao YANG, Yilin CHANG, Jing WANG, and Junyan HUO
Automatic exposure (AE) is one of the indispensable functions of modern video cameras. According to the attention mechanism of human visual systems, peak regions in luminance histogram correspond to the region of no interest in an image. Based on this assumption, a new AE algorithm using the luminance histogram of an iAutomatic exposure (AE) is one of the indispensable functions of modern video cameras. According to the attention mechanism of human visual systems, peak regions in luminance histogram correspond to the region of no interest in an image. Based on this assumption, a new AE algorithm using the luminance histogram of an image is proposed in this paper. The algorithm finds the first two largest peak regions in the histogram and calculates the mean weighted luminance (MWL) of the entire image by weighting the luminance of pixels inside the two peak regions. The MWL is then used to control the exposure of video cameras. The weight of pixel luminance is decided by a set of quadratic curves, and the parameters of the quadratic curves are affected by the brightness of the image background. Fuzzy logic is also applied to optimize the practical AE systems. Results show that the proposed algorithm gives efficient exposure control over various scene tests..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 285 (2008)
Progress of super-resolution near-field structure in near-field optical storage technology
Xiaofei YANG, Qian LI, and Xiaomin CHENG
Super-resolution near-field structure (Super-RENS) is one of the most promising near-field optical recording schemes with significant application prospects. The development of Super-RENS from the basic type to the third-generation is introduced. The development of mask material and the application of Super-RENS in diffSuper-resolution near-field structure (Super-RENS) is one of the most promising near-field optical recording schemes with significant application prospects. The development of Super-RENS from the basic type to the third-generation is introduced. The development of mask material and the application of Super-RENS in different recording systems are summarized..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 292 (2008)
Synthesis, optical and electroluminescent properties of novel polyfluorene/carbazole-based conjugated polyelectrolytes and their precursors
Wei CAO, Haixing DONG, Fei HUANG, Huilin SHEN, and Yong CAO
A series of novel aminoalkyl-substituted fluorene/carbazole-based main chain copolymers with benzothiadiazole (BTDZ) of different contents: poly[3,6-(N-(2-ethylhexyl)carbazole)-(9,9-bis(39-(N,N-dimethylamino) propyl)-2,7-fluorene)-4,7-(2,1,3-benzothiadiazole)] (PCzN-BTDZ) were synthesized by Suzuki coupling reaction. TA series of novel aminoalkyl-substituted fluorene/carbazole-based main chain copolymers with benzothiadiazole (BTDZ) of different contents: poly[3,6-(N-(2-ethylhexyl)carbazole)-(9,9-bis(39-(N,N-dimethylamino) propyl)-2,7-fluorene)-4,7-(2,1,3-benzothiadiazole)] (PCzN-BTDZ) were synthesized by Suzuki coupling reaction. Through a postpolymerization treatment on the precursor polymer, a corresponding quaternized ammonium polyelectrolyte derivatives: poly[3,6-(N-(2-ethylhexyl)carbazole)-(9,9-bis(39-((N,N-dimethyl)-Nethylammonium) propyl)-2,7-fluorene)-4,7-(2,1,3-benzothiadiazole)] dibromide (PCzNBr-BTDZ) were obtained. It was found that devices from such polymers with high work-function metal cathode such as Al showed similar device performance to that by using low work-function cathode such as Ba, indicating the excellent electron injection ability of these polymers. The efficient energy transfer from fluorene-carbazole segment to the narrow band gap BTDZ site for both the neutral and the quaternized copolymers was also observed. The addition of BTDZ into the polymer main chain can also improve polymer LED (PLED) device performance. When poly(3,4-ethylenedioxythiophene) (PEDOT)/poly(vinylcarbazole) (PVK) was used as an anode buffer, the external quantum efficiency of the copolymer PCzN-BTDZ1 was 0.99%, which was much higher than the copolymer PCzN without the incorporation of BTDZ in the same device configuration..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 299 (2008)
SiC/Mg multilayer reflective mirror for He-II radiation at 30.4 nm and its thermal stability
Jingtao ZHU, Da XU, Shumin ZHANG, Wenjuan WU, Zhong ZHANG, Fengli WANG, Bei WANG, Cunxia LI, Yao XU, Zhanshan WANG, Lingyan CHEN, Hongjun ZHOU, and Tonglin HUO
In applications of solar physics, extreme ultraviolet imaging of solar corona by selecting the He-II (l530.4 nm) emission line requires high reflectivity multilayer mirrors. Some material combinations were studied to design the mirrors working at a wavelength of 30.4 nm, including SiC/Mg, B4C/Mg, C/Mg, C/Al, Mo/Si, B4CIn applications of solar physics, extreme ultraviolet imaging of solar corona by selecting the He-II (l530.4 nm) emission line requires high reflectivity multilayer mirrors. Some material combinations were studied to design the mirrors working at a wavelength of 30.4 nm, including SiC/Mg, B4C/Mg, C/Mg, C/Al, Mo/Si, B4C/Si, SiC/Si, C/Si, and Sc/Si. Based on optimization of the largest reflectivity and the narrowest width for the multilayer mirror, a SiC/Mg material combination was selected as the mirror and fabricated by a magnetron sputtering system. The layer thicknesses of the SiC/Mg multilayer were measured by an X-ray diffractometer. Reflectivities were then measured on beamline U27 at the National Synchrotron Radiation Laboratory (NSRL) in Hefei, China. At a wavelength of 30.4 nm, the measured reflectivity is as high as 38.0%. Furthermore, a series of annealing experiments were performed to investigate the thermal stability of the SiC/Mg multilayer..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 305 (2008)
Photoresponse of ZnO single crystal films
Ying LI, Shiwei FENG, Ji YANG, Yuezong ZHANG, Xuesong XIE, Changzhi LV, and Yicheng LU
The ohmic contact and photoresponse of a ZnO single crystal film by metalorganic chemical vapor deposition (MOCVD) were investigated. The electrical and photoresponsive changes in the ZnO film due to RF sputter deposition of SiO2 (antireflection coating) were also discussed. The experimental results show that the non-aThe ohmic contact and photoresponse of a ZnO single crystal film by metalorganic chemical vapor deposition (MOCVD) were investigated. The electrical and photoresponsive changes in the ZnO film due to RF sputter deposition of SiO2 (antireflection coating) were also discussed. The experimental results show that the non-alloyed Al/Au metallization scheme forms good ohmic contact on n-type ZnO, RF sputter deposition of SiO2 induces defects which behave as carrier traps and prolong response time, and the photoresponse of ZnO epitaxial film deteriorates with time..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 309 (2008)
AlGaAs/GaAs quantum well infrared photodetector focal plane array based on MOCVD technology
Xianjie LI, Yingbin LIU, Zhen FENG, Fan GUO, Yonglin ZHAO, Run ZHAO, Rui ZHOU, Chen LOU, and Shizu ZHANG
1286128, 1286160 and 2566256 AlGaAs/GaAs quantum well infrared photodetector (QWIP) focal plane arrays (FPA) as well as a large area test device are designed and fabricated. The device with n-doped backilluminated AlGaAs/GaAs quantum structure is achieved by metal organic chemical vapor deposition (MOCVD) epitaxial gro1286128, 1286160 and 2566256 AlGaAs/GaAs quantum well infrared photodetector (QWIP) focal plane arrays (FPA) as well as a large area test device are designed and fabricated. The device with n-doped backilluminated AlGaAs/GaAs quantum structure is achieved by metal organic chemical vapor deposition (MOCVD) epitaxial growth and GaAs integrated circuit processing technology. The test device is valued by its dark current performance and Fourier transform infrared spectroscopy (FTIR) spectra at 77 K. Cut off wavelengths of 9 and 10.9 mm are realized by using different epitaxial structures. The blackbody detectivity DB* is as high as 2.66 109 cm·Hz1/2·W21. The 1286128 FPA is flip-chip bonded on a CMOS readout integrated circuit with indium (In) bumps. The infrared thermal images of some targets under room temperature background have been successfully demonstrated at 80 K operating temperature. In addition, the methods to further improve the image quality are discussed..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 313 (2008)
Investigation on electromagnetically induced transparency and slowdown of group velocity in an Eu3+:Y2SiO5 crystal
Qingchang LIANG, Haihua WANG, and Zhankui JIANG
Electromagnetically induced transparency (EIT) and slowdown of group velocity (SGV) in Eu3+:Y2SiO5 were investigated by using density matrix equations of the interaction between light and matter and their numerical solutions. The relationship of the probe transmission with different probe detuning and coupling Rabi freElectromagnetically induced transparency (EIT) and slowdown of group velocity (SGV) in Eu3+:Y2SiO5 were investigated by using density matrix equations of the interaction between light and matter and their numerical solutions. The relationship of the probe transmission with different probe detuning and coupling Rabi frequency was obtained. The influence of inhomogeneous line width on electromagnetically induced transparency and slowdown of group velocity were analyzed. Such transparency was restrained when inhomogeneous line width increased. The center transmission did not homogeneously change with an increase in ion-doped concentration. There is an optimal concentration which can make the electromagnetically induced transparency significant. It is evident that the group velocity of the probe has a minimum value for a certain level of coupling field strength..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 318 (2008)
Organic electroluminescent characteristics of PS:NPB composite hole transporting layer
Fan SUO, Junsheng YU, Jing DENG, Shuangling LOU, and Yadong JIANG
Green organic light-emitting devices with a structure of indium-tin-oxide (ITO)/polystyrene (PS):N,N9-bis-(3-naphthyl)-N,N9-biphenyl-(1,19-biphenyl)-4,49-diamine (NPB)/tris-(8-hydroxyquinoline)-aluminum (Alq3)/Mg:Ag were fabricated. A doping system consisting of small-molecular hole transporting material NPB and polymeGreen organic light-emitting devices with a structure of indium-tin-oxide (ITO)/polystyrene (PS):N,N9-bis-(3-naphthyl)-N,N9-biphenyl-(1,19-biphenyl)-4,49-diamine (NPB)/tris-(8-hydroxyquinoline)-aluminum (Alq3)/Mg:Ag were fabricated. A doping system consisting of small-molecular hole transporting material NPB and polymeric matrix PS was applied as a composite hole transporting layer (HTL), and the thin film preparation was simplified via spin-coating technique. By adjusting the component ratio of the doping system, several devices with different concentration proportion of PS:NPB are constructed. The electroluminescent characteristics of the devices were investigated and discussed. This study demonstrated that the difference of doping concentration of NPB has a remarkable impact on the optoelectronic performance of both HTL and the devices. Optimum device performance can be obtained by choosing a suitable concentration proportion of PS:NPB at 1:1. This study contributes to the construction of composite functional layers of organic light-emitting diode (OLED) devices and to the technical modification..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 323 (2008)
Theoretical and experimental research on Er-doped and Yb-Er co-doped Al2O3 waveguide amplifiers
Shufeng LI, Chengren LI, and Changlie SONG
The rate equations of Er-doped and Yb-Er codoped systems pumped at 0.98 mm are presented, with consideration for the upconversion mechanisms such as cooperative upconversion, cross relaxation, and excited state absorption. A multi-theoretical model is founded to analyze the gain characteristics of Er-doped and Yb-Er coThe rate equations of Er-doped and Yb-Er codoped systems pumped at 0.98 mm are presented, with consideration for the upconversion mechanisms such as cooperative upconversion, cross relaxation, and excited state absorption. A multi-theoretical model is founded to analyze the gain characteristics of Er-doped and Yb-Er co-doped Al2O3 waveguide amplifiers by using rate equations, a two-dimension waveguide finite element model and propagation equations with forward and backward amplified spontaneous emission. The dependence of the gain on amplifier length, pump power and doping concentration is obtained. The optimum design curve is given for designing waveguide amplifiers. The new theory is used to analyze the gain performance of a practical Yb-Er co-doped Al2O3 waveguide amplifier, and the analyzed results are in accordance with the experimental data..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 329 (2008)
Monolithically integrated long wavelength photoreceiver OEIC based on InP/InGaAs HBT technology
Xianjie LI, Yonglin ZHAO, Daomin CAI, Qingming ZENG, Yunzhang PU, Yana GUO, Zhigong WANG, Rong WANG, Ming QI, Xiaojie CHEN, and Anhuai XU
The epitaxial structure and growth, circuit design, fabrication process and characterization are described for the photoreceiver opto-electronic integrated circuit (OEIC) based on the InP/InGaAs HBT/PIN photodetector integration scheme. A 1.55 mm wavelength monolithically integrated photoreceiver OEIC is demonstrated wThe epitaxial structure and growth, circuit design, fabrication process and characterization are described for the photoreceiver opto-electronic integrated circuit (OEIC) based on the InP/InGaAs HBT/PIN photodetector integration scheme. A 1.55 mm wavelength monolithically integrated photoreceiver OEIC is demonstrated with self-aligned InP/InGaAs heterojunction bipolar transistor (HBT) process. The InP/InGaAs HBT with a 2 mm×8 mm emitter showed a DC gain of 40, a DC gain cutoff frequency of 45 GHz and a maximum frequency of oscillation of 54 GHz. The integrated InGaAs photodetector exhibited a responsivity of 0.45 A/W at l51.55 mm, a dark current less than 10 nA at a bias of 25 V and a 23 dB bandwidth of 10.6 GHz. Clear and opening eye diagrams were obtained for an NRZ 22321 pseudorandom code at both 2.5 and 3.0 Gbit/s. The sensitivity for a bit error ratio of 1029 at 2.5 Gbit/s is less than 215.2 dBm..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 336 (2008)
Optical properties of InN films grown by MOCVD
Jieying KONG, Bin LIU, Rong ZHANG, Zili XIE, Yong ZHANG, Xiangqian XIU, and Youdou ZHENG
By means of optical absorption, photoluminescence (PL), Raman scattering and ellipsometry, optical properties of indium nitride (InN) films grown by metal organic chemical vapor deposition (MOCVD) are investigated. Through absorption and PL measurements, it is proven that the band gap of high quality InN is 0.68 eV, whBy means of optical absorption, photoluminescence (PL), Raman scattering and ellipsometry, optical properties of indium nitride (InN) films grown by metal organic chemical vapor deposition (MOCVD) are investigated. Through absorption and PL measurements, it is proven that the band gap of high quality InN is 0.68 eV, which agrees with the recently reported value, 0.7 eV. By analysis of the Raman scattering spectrum, the comparatively low background concentration of electron results in a smaller band gap value. The transition energy of wurtzite InN at critical point is determined by ellipsometric spectra. In addition, the complex refractive index of InN at energy ranging from 0.65 to 4.0 eV is obtained for the first time..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 341 (2008)
Fringe-contoured-window sine/cosine filter for saw-tooth phase maps in ESPI
Sihua FU, Xuejun LONG, Hui LIN, and Qifeng YU
In electronic speckle pattern interferometry (ESPI), because saw-tooth phase map obtained by phaseshifting is inherently full of speckle noise, noise reduction should be carried out to suppress high-level noise before it is unwrapped. In accordance with the feature of the saw-tooth phase map, an adaptive filter method In electronic speckle pattern interferometry (ESPI), because saw-tooth phase map obtained by phaseshifting is inherently full of speckle noise, noise reduction should be carried out to suppress high-level noise before it is unwrapped. In accordance with the feature of the saw-tooth phase map, an adaptive filter method combining the classical sine/cosine filter and the fringe orientation information of the phase map is developed. A fringe orientation map is first generated from the saw-tooth phase map, and then a fringe-contoured window is derived accordingly. Finally, filtering is carried out within the window. Compared with existing filters, it has a better performance on phase jump information preservation without any blurring effect on phase distribution provided that filtering is implemented on the equal-phase window. Moreover, its capability for noise reduction is more powerful. The effectiveness and advantages of the novel filter have been also verified by both simulated and real saw-tooth phase maps..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 3, 345 (2008)
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