[1]红外动目标识别跟踪系统的dsp+fpga实现




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Crystal Fibres


221

Author(s): Geng, D (Geng Dan); Yang, DX (Yang Dong-Xiao); Shen, GF (Shen Guo-Feng); Zhang, XM (Zhang Xian-Min)

Title: Photonic crystal fibre Brillouin laser based on Bragg grating Fabry-Perot cavity

Source: CHINESE PHYSICS B, 17 (3): 1020-1024 MAR 2008

Abstract:

A photonic crystal fibre Brillouin laser based on fibre Bragg grating Fabry-Perot cavity is presented. A highly nonlinear photonic crystal fibre 25m in length is used as Brillouin gain medium and fibre Bragg grating Fabry Perot cavity is chosen in order to enhance the laser conversion efficiency and suppress the higher-order Stokes waves. The laser reaches the threshold at input power of 35 mW, and the experimental laser conversion efficiency achieves 18% of the input power of 140 mW and does not show higher-order Stokes waves. A photonic crystal fibre Brillouin laser with shorter fibre length and lower threshold is experimentally realized.


Addresses: Zhejiang Univ, Dept Informat & Elect Engn, Hangzhou 310027, Peoples R China

Reprint Address: YANG, DX, ZHEJIANG UNIV, DEPT INFORMAT & ELECT ENGN, HANGZHOU 310027, PEOPLES R CHINA

Author's E-mail: yangdx@zju.edu.cn

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222

Author(s): Chen, W (Chen Wei); Li, JY (Li Jin-Yan); Lu, PX (Lu Pei-Xiang); Li, SY (Li Shi-Yu); Ji, LL (Ji Ling-Ling); Jiang, ZW (Jiang Zuo-Wen); Zhang, JH (Zhang Ji-Huang); Peng, JG (Peng Jing-Gang)



Title: All-fibre ytterbium-doped photonic crystal fibre laser with high efficiency

Source: CHINESE PHYSICS LETTERS, 25 (3): 960-962 MAR 2008

Abstract:

A double-cladding ytterbium-doped photonic crystal fibre (PCF) with a 350-mu m(2) effective area is fabricated. The measurement results show that the PCF has high absorption peak at 915 nm. Its fluorescence lifetime is 840 mu s. Laser experiments with all-fibre configurations are carried out with this fibre. A continuous-wave output power of 3.96W is achieved with a 5.2W launched pump power. The central wavelength of the output spectrum is 1080.22 nm. The results show that the PCF laser has a high slope efficiency of 79.6% and light conversion efficiency of 76.2%.


Addresses: Huazhong Univ Sci & Technol, Wuhan Natl Lab Optoelect, Wuhan 430074, Peoples R China

Fiberhome Telecommun Technol Co Ltd, Natl Key Lab Next Generat Fiber Commun Technol &, Wuhan 430074, Peoples R China

Reprint Address: LU, PX, HUAZHONG UNIV SCI & TECHNOL, WUHAN NATL LAB OPTOELECT, WUHAN 430074, PEOPLES R CHINA

Author's E-mail: lupeixiang@mail.hust.edu.cn

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223


Author(s): Zhang, DS (Zhang De-Sheng); Sheng, QQ (Sheng Qiu-Qin); Dong, XY (Dong Xiao-Yi)

Title: Properties of zero dispersion wavelengths in silica strands and photonic crystal fibres

Source: CHINESE PHYSICS LETTERS, 25 (3): 993-995 MAR 2008

Abstract:

To design and calculate the zero-dispersion wavelength is one of the important aspects for highly nonlinear photonic crystal fibres. By using the air filling fraction f defined as f = (6d)/(2 pi Lambda) here for the cladding effective index, and the step effective index model, the relationship between the properties of chromatic dispersion and the two different structures has been analysed. It is pointed that the variation of the zero dispersion wavelength is insensitive to the core diameter change in one range of core diameter D, while keeping the air filling fraction f constant. In the other range of core diameter D, the photonic crystal fibres have the best nearly-zero ultra-flattened dispersion. These properties are significant to the design of chromatic dispersion and zero dispersion wavelength in photonic crystal fibres.
Addresses: Nankai Univ, Inst Phys Sci, Tianjin 300071, Peoples R China

Reprint Address: ZHANG, DS, NANKAI UNIV, INST PHYS SCI, TIANJIN 300071, PEOPLES R CHINA

Author's E-mail: tozds@yahoo.com

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224

Author(s): Zhang, YJ (Zhang, Yanjie); Lu, JJ (Lu, Jinjun)



Title: The transformation of single-crystal calcium phosphate ribbon-like fibres to hydroxyapatite spheres assembled from nanorods - art. no. 155608

Source: NANOTECHNOLOGY, 19 (15): 55608-55608 APR 16 2008

Abstract:

Two precursors of ribbon-like anhydrous dicalcium phosphate ( DCPA) and calcium phosphate fibres were successfully synthesized at 85 degrees C through a simple and mild pathway from Ca(NO3)(2)center dot 4H(2)O and (NH4)(2)HPO4 upon the hydrolysis of urea. Different molar concentrations of urea resulted in different precursors, including precursor I ( DCPA phase) and precursor II (calcium phosphate with DCPA, octacalcium phosphate (OCP) and hydroxyapatite (HAp) phase). By immersing the two precursors in ammonium hydroxide solution (pH = 12), the transformation from precursors to hydroxyapatite could be achieved. X-ray diffraction (XRD) results combined with transmission electron microscopy (TEM) indicated that DCPA fibres (precursor I) were transformed to HAp nanorods in transformation I. In transformation II, dandelion-like spheres assembled by HAp nanorods were obtained from calcium phosphate ( precursor II). The mechanisms of transformations I and II are also proposed and discussed based on the XRD and TEM results.


Addresses: Chinese Acad Sci, Lanzhou Inst Chem Phys, State Key Lab Solid Lubricat, Lanzhou 730000, Peoples R China

Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China

Reprint Address: LU, JJ, CHINESE ACAD SCI, LANZHOU INST CHEM PHYS, STATE KEY LAB SOLID LUBRICAT, LANZHOU 730000, PEOPLES R CHINA

Author's E-mail: jjlu@lzb.ac.cn

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225


Author(s): Li, YZ (Li Yong-Zhong); Qian, LJ (Qian Lie-Jia); Lu, DQ (Lu Da-Quan); Fan, DY (Fan Dian-Yuan); Cheng, GH (Cheng Guang-Hui)

Title: Widely tunable dual-pump parametric amplifiers with photonic crystal fibres

Source: CHINESE PHYSICS B, 17 (1): 205-210 JAN 2008

Abstract:

This paper theoretically studies the double-pumped fibre-optical parametric amplifiers (FOPAs) in photonic crystal fibres. Two distinct working regimes of FOPAs are researched, which depend on the dispersion at the central wavelength of the two pumps. Extremely broad tuning range can be obtained when the central pump wavelength is in the normal dispersion regime and is insensitive to the wavelength separation between the two pumps, while the tuning range is narrow in the anomalous dispersion regime and can be significantly enhanced by increasing the wavelength separation. Impacts of higher-order dispersions and temporal walk-off on the gain spectra are also discussed.
Addresses: Fudan Univ, Dept Opt Sci & Engn, State Key Lab Adv Mat & Dev, Shanghai 200433, Peoples R China

China Elect Technol Grp Corp, Elect Res Inst 23, Shanghai 200437, Peoples R China

Reprint Address: QIAN, LJ, FUDAN UNIV, DEPT OPT SCI & ENGN, STATE KEY LAB ADV MAT & DEV, SHANGHAI 200433, PEOPLES R CHINA

Author's E-mail: ljqian@fudan.edu.cn

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226


Author(s): Xiong, C (Xiong, C.); Wadsworth, WJ (Wadsworth, W. J.)

Title: Polarized supercontinuum in birefringent photonic crystal fibre pumped at 1064 nm and application to tuneable visible/UV generation

Source: OPTICS EXPRESS, 16 (4): 2438-2445 FEB 18 2008

Abstract:

We generate a flat, polarized and single mode supercontinuum (SC) spanning 450-1750 nm in a highly birefringent photonic crystal fibre (PCF) pumped by a 1064 nm microchip laser. More than 99% of the total power is kept in a single linear polarization. The measured power coupling penalty due to the elliptical core is less than 6% (0.25 dB). As one of its applications, we demonstrate tuneable visible/UV generation in the nonlinear crystal BIBO pumped by this polarized SC source. A tuneable range of 400-525 nm is obtained by critical phase matching in BIBO. We also show the results of visible/UV generation in BIBO pumped by the signal wavelength of polarized four-wave mixing (FWM) in PCF. (C) 2008 Optical Society of America.
Addresses: Univ Bath, Dept Phys, Ctr Photon & Photon Mat, Bath BA2 7AY, Avon, England

Reprint Address: XIONG, C, UNIV BATH, DEPT PHYS, CTR PHOTON & PHOTON MAT, BATH BA2 7AY, AVON, ENGLAND

Author's E-mail: w.j.wadsworth@bath.ac.uk

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227

Author(s): Yang, Y (Yang Yong); Tang, YL (Tang Yu-Long); Xu, JQ (Xu Jian-Qiu); Hang, Y (Hang Yin)



Title: Tm-doped fibre laser pumped Cr2+: ZnSe poly-crystal laser

Source: CHINESE PHYSICS LETTERS, 25 (1): 116-118 JAN 2008

Abstract:

Demonstrations of cw lasing in Cr2+:ZnSe poly-crystal are reported. The laser consists of a 1.7-mm-thick Cr2+:ZnSe poly-crystal disc pumped by a Tm-silica double-clad fibre laser at 2050nm. Using a concave high-reflection mirror with a radius of curvature of 500mm as the rear mirror, the laser delivers up to 1030mW of radiation around 2.367 mu m.


Addresses: Chinese Acad Sci, Shanghai Inst Opt & Fine Mech, Shanghai 201800, Peoples R China

Reprint Address: YANG, Y, CHINESE ACAD SCI, SHANGHAI INST OPT & FINE MECH, SHANGHAI 201800, PEOPLES R CHINA

Author's E-mail: xianji@siom.ac.cn

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228

Author(s): Jin, L (Jin Long); Guan, BO (Guan Bai-Ou); Fang, Q (Fang Qiang); Wang, Z (Wang Zhi); Liu, B (Liu Bo); Liu, JG (Liu Jian-Guo); Yue, Y (Yue Yang); Kai, GY (Kai Gui-Yun); Dong, XY (Dong Xiao-Yi)



Title: Bragg gratings written in photonic crystal fibres with a high-index germanosilicate core

Source: CHINESE PHYSICS LETTERS, 25 (1): 160-163 JAN 2008

Abstract:

Bragg gratings are straightforwardly written into a 10-ring photonic crystal fibre ( PCF) with a highly Ge3+-doped core by means of a 193nm ArF excimer laser. The grating inscription efficiency is improved, due to enhanced photosensitivity and the large overlap between the fundamental mode and the photosensitive core. The exposure duration only lasts less than 180 s. In addition, the high-index core changes the modal properties of the PCF and two groups of higher order mode resonance dips are therefore obtained. A strong cladding mode resonance is observed, because the LP02-like mode has a large overlap integral with the fundamental mode.


Addresses: Nankai Univ, Inst Modern Opt, Key Lab Optoelect Informat Sci & Technol, Minist Educ, Tianjin 300071, Peoples R China

Dalian Univ Technol, Sch Phys & Optoelect Technol, Dalian 116024, Peoples R China

Reprint Address: JIN, L, NANKAI UNIV, INST MODERN OPT, KEY LAB OPTOELECT INFORMAT SCI & TECHNOL, MINIST EDUC, TIANJIN 300071, PEOPLES R CHINA

Author's E-mail: kingbay@gmail.com

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229


Author(s): Cascante-Vindas, J (Cascante-Vindas, J.); Diez, A (Diez, A.); Cruz, JL (Cruz, J. L.); Andres, MV (Andres, M. V.); Silvestre, E (Silvestre, E.); Miret, JJ (Miret, J. J.); Ortigosa-Blanch, A (Ortigosa-Blanch, A.)

Title: Tapering photonic crystal fibres for supercontinuum generation with nanosecond pulses at 532 nm

Source: OPTICS COMMUNICATIONS, 281 (3): 433-438 FEB 1 2008

Abstract:

Experimental results on supercontinuum generation in photonic crystal fibre tapers using pump pulses of 7 ns duration at 532 nut are presented. Photonic crystal fibre tapers with the first wavelength of zero dispersion around 532 nm were fabricated. The generation of supercontinuum was investigated in normal and anomalous dispersion regimes. Supercontinuum spectra spanning more than 400 nm in the visible region are reported. (C) 2007 Elsevier B.V. All rights reserved.
Addresses: Univ Valencia, Dept Fis Aplicada, ICMUV, Burjassot 46100, Spain

Univ Valencia, Dept Opt, Burjassot 46100, Spain

Univ Alicante, Dept Opt, Alicante 08080, Spain

Univ Politecn Valencia, ITEAM Res Inst, Opt & Quantum COmmun Grp, Valencia, Spain

Reprint Address: DIEZ, A, UNIV VALENCIA, DEPT FIS APLICADA, ICMUV, DR MOLINER 50, BURJASSOT 46100, SPAIN

Author's E-mail: antonio.diez@uv.es

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230


Author(s): Haxha, S (Haxha, S.); Ademgil, H (Ademgil, H.)

Title: Novel design of photonic crystal fibres with low confinement losses, nearly zero ultra-flatted chromatic dispersion, negative chromatic dispersion and improved effective mode area

Source: OPTICS COMMUNICATIONS, 281 (2): 278-286 JAN 15 2008

Abstract:

A novel photonic crystal fibre (PCF) with a low confinement loss and nearly zero ultra-flatted chromatic dispersion and negative chromatic dispersion at a wide telecommunication window is presented. Important PCF design parameters, such as the effects of air holes and geometrical parameters on the effective index, confinement losses, chromatic dispersion and effective mode area, have been thoroughly investigated by employing the full vectorial finite element method. Significant reduction of the confinement loss and low chromatic dispersion of the PCF, with three rings of air holes, has been obtained by carefully incorporating additional air holes. (c) 2007 Elsevier B.V. All rights reserved.
Addresses: Univ Kent, Dept Elect, Broadband & Wireless Commun Grp, Canterbury CT2 7NT, Kent, England

Reprint Address: HAXHA, S, UNIV KENT, DEPT ELECT, BROADBAND & WIRELESS COMMUN GRP, CANTERBURY CT2 7NT, KENT, ENGLAND

Author's E-mail: S.Haxha@kent.ac.uk

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