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81.
Via a cascaded structure, the peak-to-trough ratio is considerably improved for sampled fiber Bragg gratings (SFBGs) based on multiple-phase-shift (MPS) technique. This cascaded filter is composed of two identical SFBGs which are inserted with the increasing or decreasing arrangement of phase shifts. With this inverse arrangement of MPS in grating design, the phase fluctuation of individual SFBG can be compensated, and as a result an excellent phase matching condition is realized. In this way, the peak-to- trough ratio in reflection spectra is improved from 6 to 12 dB when multiplication factor m = 4, and from 5dBto 10dBwhenm=8. 相似文献
82.
Huang Lingxiong Zhang Ge Huang Chenghui Wei Yong Zhu Haiyong 《Journal of Russian Laser Research》2008,29(6):593-598
We develop a separate 1319 and 1338 nm Nd:YAG laser system with a blazing grating (600 lines/mm). The resonator of this system
has a Littrow grating configuration and a highly reflective mirror, in which the zero-order diffraction of the grating acts
as the laser output. By virtue of the wavelength-dependent reflectivity of the grating, a single-wavelength laser at 1319
nm or 1338 nm can be realized. In view of the laser rate equations and using the distribution of the blazing grating, we analyze
the oscillation conditions providing single-wavelength laser operation in the system. 相似文献
83.
A 1.55-m fiber grating laser (FGL) was fabricated by optically packaging a non-anti-reflection (AR) coated Fabry–Perot (FP) laser to a lensed fiber grating. The FGL demonstrates a single-longitudinal mode operation with a side-mode suppression ratio (SMSR) of up to 40 dB. The SMSR oscillates and diminishes to <30 dB as the increase of injection current above 38 mA, and the tilt of the fiber approaches 5° away from the facet normal of the FP laser. We have performed numerical simulations on the single-longitudinal mode operation for the FGL. The SMSR for the FGL increases over 40 dB as the increase of the fiber grating reflectivity (R
g) above 0.7 with non-AR-coated FP laser facet. Our calculations also show that the strong current-dependent SMSR oscillation is from the mode selection by the fiber grating external cavity and the heating effect in the FP laser. 相似文献
84.
Marek Wichtowski Andrzej Ziółkowski Ewa Weinert-Rączka 《Central European Journal of Physics》2008,6(3):546-554
In our work we propose a novel method of analysis of photorefractive transport equations. The method based on a perturbative
approach can be used in the case of two wave mixing and four wave mixing geometry, i.e. for the samples illuminated by interference
patterns. Presented approach can be employed for a broad range of material and experimental parameters, particularly for arbitrary
depth of light modulation pattern. The approximate analytical solution is compared with results of numerical calculations
and a good agreement practically in every case was found.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Šwinoujście, Poland 相似文献
85.
曝光系统离焦对平面全息光栅衍射波前的影响 总被引:1,自引:0,他引:1
波前像差是衍射光栅的重要技术指标,它直接影响光栅的分辨率。由光致刻蚀剂记录两束相干光干涉条纹是制作全息光栅的关键步骤。为了提高全息光栅曝光系统调整精度、减小离焦、降低光栅的衍射波前像差,从离焦对反射球面准直镜的准直光平行度的影响程度出发,分析了准直光平行度对全息光栅衍射波前像差的影响。理论分析和数值模拟结果表明,准直镜调整误差直接决定全息光栅衍射波前像差大小。以3种不同刻线密度光栅为例,得出了准直镜调整误差的允许变化范围。 相似文献
86.
87.
一种多波长窄线宽环形掺铒光纤激光器 总被引:2,自引:0,他引:2
本文提出了一种利用多个光纤光栅串接来实现环形掺铒光纤多波长,窄线宽激光器的新颖方法,并在实验中验证了这一设计的合理性,得到了稳定的双波长输出。 相似文献
88.
通过化学反应,在三醋酸纤维素睛基的正反两面同时生成具有感光活性的光敏层的方法,获得了一种具有叠层光敏性的全息记录软片:重铬酸盐-三醋酸纤维素酯。由该软片记录的叠层体积全息光栅,具有迄今为止,最高的一级实验衍射效率(54%)。 相似文献
89.
Yande Xu 《Optical Review》2004,11(5):303-307
This paper proposes a new measuring method called two-period interference fringe interferometry, for a step-profile altitude difference measurement. The principle of the method is different from that of the two-wavelength interferometry which is widely known. The two interference fringes with only slight difference between their spatial periods are obtained by turning a binary step-grating, and they produce a synthetic equivalent period much longer than either of the two periods alone. The interference fringes are produced by the ±1st-order beams diffracted from the grating. The intensity distribution of the interference pattern is independent of the wavelength of the laser-diode light source used. The measuring range of this method is much larger than that of the two-wavelength interferometery. Sinusoical phase modulating technique is easily applied to detect the phase distribution of the interference pattern by vibrating the grating sinusoidally. A plane reflector of 3mm thickness is measured to verify this novel method. 相似文献
90.