LD side-pumped high beam quality passive Q-switched and mode-locked Nd:YAG laser based on SESAM

We report a LD side-pumped fundamental-mode (Mx(2) = 1.35 and My(2) = 1.27) passive Q-switched and mode-locked Nd:YAG laser based on a semiconductor saturable absorber mirror (SESAM). At a pump current of 12.5 A, the average output power of 5.68 W with 80 kHz repetition rate and 2 mu s pulse width of the Q-switched envelope was generated. The repetition rate of the mode-locked pulse within the Q-switched envelope of 88 MHz was achieved.

Low heat and high efficiency Nd:GdVO4 laser pumped by 913 nm

A Nd:GdVO4 crystal is pumped directly into its emitting level at 913 nm for the first time to the best of our knowledge. 3.35 W output laser emitting at 1063 nm is achieved in a 1.1 at.% Nd-doped Nd:GdVO4. The crystal absorbs pumping light of 4.30 W at 913 nm and produces a very low quantity of heat with the opto-optic conversion efficiency of 77.2%. The average slope efficiency is 81.2% from 0.21 W, at the threshold, to 4.30 W of absorbed pump power. Because of the very weakly thermal effect, the near-diffraction-limit beam is easily obtained with beam quality factor of M-2 approximate to 1.1.

面向红外、紫外焦平面阵列的读出电路的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T05:22:14Z No. of bitstreams: 1 马文龙.pdf: 4959193 bytes, checksum: 501f2cb82abb2517c6a3442aa5a11a3c (MD5)

Compact four-channel reconfigurable optical add-drop multiplexer using silicon photonic wire (vol 282, pg 3477, 2009)

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-04T06:57:43Z No. of bitstreams: 1 71.pdf: 92858 bytes, checksum: 2a0a4972af8e56b0fced818042dd6dbd (MD5)

Pipeline Architecture and Parallel Computation-Based Real-Time Stereovision Tracking System for Surgical Navigation

This paper studies the development of a real-time stereovision system to track multiple infrared markers attached to a surgical instrument. Multiple stages of pipeline in field-programmable gate array (FPGA) are developed to recognize the targets in both left and right image planes and to give each target a unique label. The pipeline architecture includes a smoothing filter, an adaptive threshold module, a connected component labeling operation, and a centroid extraction process. A parallel distortion correction method is proposed and implemented in a dual-core DSP. A suitable kinematic model is established for the moving targets, and a novel set of parallel and interactive computation mechanisms is proposed to position and track the targets, which are carried out by a cross-computation method in a dual-core DSP. The proposed tracking system can track the 3-D coordinate, velocity, and acceleration of four infrared markers with a delay of 9.18 ms. Furthermore, it is capable of tracking a maximum of 110 infrared markers without frame dropping at a frame rate of 60 f/s. The accuracy of the proposed system can reach the scale of 0.37 mm RMS along the x- and y-directions and 0.45 mm RMS along the depth direction (the depth is from 0.8 to 0.45 m). The performance of the proposed system can meet the requirements of applications such as surgical navigation, which needs high real time and accuracy capability.

基于IEEE802.11n 的MIMO-OFDM 算法研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T05:24:22Z No. of bitstreams: 1 鉴海防.pdf: 4830504 bytes, checksum: e38f23ff06bf16bda48b7ef96b7511ac (MD5)

Dispersion characteristics of nanometer-scaled silicon rib waveguides

We investigate the dispersion properties of nanometer-scaled silicon waveguides with channel and rib cross section around the optical fiber communication wavelength and systematically study their relationship with the key structural parameters of the waveguide. The simulation results show that the introduction of an extra degree of freedom in the rib depth enables the rib waveguide more flexible in engineering the group velocity dispersion (GVD) compared with the channel waveguide. Besides, we get the structural parameters of the waveguides that can realize zero-GVD at 1550 nm.

Investigation on a pressure-gradient fiber laser hydrophone

In this paper, a pressure-gradient fiber laser hydrophone is demonstrated. Two brass diaphragms are installed at the end of a metal cylinder as sensing elements. A distributed feedback fiber laser, fixed at the center of the two diaphragms, is elongated or shortened due to the acoustic wave. There are two orifices at the middle of the cylinder. So this structure can work as a pressure-gradient microphone in the acoustic field. Furthermore, the hydrostatic pressure is self-compensated and an ultra-thin dimension is achieved. Theoretical analysis is given based on the electro-acoustic theory. Field trials are carried out to test the performance of the hydrophone. A sensitivity of 100 nm MPa-1 has been achieved. Due to the small dimensions, no directivity is found in the test.

Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance

For night remote surveillance, we present a method, the range-gated laser stroboscopic imaging(RGLSI), which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser. The time delay integration in this method has no influence on the video frame rate. Compared with the traditional range-gated laser imaging, RGLSI can reduce scintillation and target speckle effects and significantly improve the image signal-to-noise ratio analyzed. Even under low light level and low visibility conditions, the RGLSI system can effectively work. In a preliminary experiment, we have detected and recognized a railway bridge one kilometer away under a visibility of six kilometers, when the effective illuminated energy is 29.5 mu J.

基于可调谐激光光谱吸收的甲烷气体检测系统研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-04-07T05:15:45Z No. of bitstreams: 1 张强博士后出站报告.pdf: 1745036 bytes, checksum: 2c69f3e543f9b443f47180b0f0cf3c80 (MD5)

分布反馈（DFB）光纤激光器的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-02T01:41:39Z No. of bitstreams: 1 博士论文-分布反馈（DFB）光纤激光器的研究-徐团伟.pdf: 5147399 bytes, checksum: 771eaf8d08647ccf92d5315fbe7f6fb4 (MD5)

基于硅基纳米线波导中的四波混频效应实现全光波长转换的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-03T13:55:27Z No. of bitstreams: 1 基于硅基纳米线波导中的四波混频效应实现全光波长转换的研究.pdf: 2790964 bytes, checksum: 4f72214aa4e57015ffaa3d52718930a1 (MD5)

光纤激光传感器PGC解调系统数字化实现的研究

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-08T13:00:21Z No. of bitstreams: 1 毕业论文-王延.pdf: 2077027 bytes, checksum: b57da02bc35cbbd5822aa0a0c5b8928b (MD5)

IEEE-1394b 光总线的弹上应用及可靠性分析

Submitted by 阎军 (yanj@red.semi.ac.cn) on 2010-06-08T13:14:54Z No. of bitstreams: 1 毕业论文－木素真.pdf: 786803 bytes, checksum: a46c35c535d39afde19bbaff8f64a4d2 (MD5)

Magnetic Properties of FePt Nanoparticles Prepared by a Micellar Method

FePt nanoparticles with average size of 9 nm were synthesized using a diblock polymer micellar method combined with plasma treatment. To prevent from oxidation under ambient conditions, immediately after plasma treatment, the FePt nanoparticle arrays were in situ transferred into the film-growth chamber where they were covered by an SiO2 overlayer. A nearly complete transformation of L1(0) FePt was achieved for samples annealed at temperatures above 700 A degrees C. The well control on the FePt stoichiometry and avoidance from surface oxidation largely enhanced the coercivity, and a value as high as 10 kOe was obtained in this study. An evaluation of magnetic interactions was made using the so-called isothermal remanence (IRM) and dc-demagnetization (DCD) remanence curves and Kelly-Henkel plots (Delta M measurement). The Delta M measurement reveals that the resultant FePt nanoparticles exhibit a rather weak interparticle dipolar coupling, and the absence of interparticle exchange interaction suggests no significant particle agglomeration occurred during the post-annealing. Additionally, a slight parallel magnetic anisotropy was also observed. The results indicate the micellar method has a high potential in preparing FePt nanoparticle arrays used for ultrahigh density recording media.