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121.
A multilayer dielectric cylindrical mirror (MDCM) based on the one-dimensional omnidirectional reflection of a photonic crystal is presented. In this case, the refractive indices of the two materials are 1.6 (polystyrene) and 4.6 (tellurium), and the corresponding optimized thicknesses are 0.75a and 0.25a. A very high reflectance over a wide frequency range is observed. In this case, a is the lattice constant of the photonic crystal. In this band, the MDCM has good reflection and focal properties. Therefore, it is feasible to use the MDCM for integrated waveguide devices. As an example, an etched diffraction grating demultiplexer based on the MDCM is also proposed. Both the operational principle and design of the device are introduced. This provides a method for designing compact integrated waveguide devices. 相似文献
122.
Simultaneous measurement of curvature and temperature based on PCF-based interferometer and fiber Bragg grating 总被引:2,自引:0,他引:2
Yan Zhou Wenjun Zhou Chi Chiu Chan Li-Yang Shao Xinyong Dong 《Optics Communications》2011,284(24):5669-5672
A sensor head consisting of a photonic crystal fiber (PCF)-based Mach-Zehnder interferometer (MZI) and a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of curvature and temperature. The MZI fabricated by splicing a short length of PCF between two single-mode fibers with the air-hole structure that completely collapsed near the splicing points, is sensitive to fiber bending and surrounding temperature, while the FBG is only sensitive to the later. Simultaneous measurement of curvature and temperature is therefore obtained. Sensitivities of 4.06 nm/m− 1 and 6.30 pm/°C are achieved experimentally for curvature and temperature, respectively. And the corresponding resolutions are 5.2 × 10− 4 m− 1 and 1.25 °C for curvature and temperature, respectively, based on the wavelength measurement resolution of 10 pm. 相似文献
123.
124.
V. V. Azharonok I. I. Filatova I. V. Voshchula V. A. Dlugunovich O. V. Tsaryuk T. N. Gorzhanova 《Journal of Applied Spectroscopy》2007,74(4):465-471
We have used laser Stokes polarimetry to study changes in the structure of paper for offset printing when exposed to a high-frequency
electromagnetic field. We have shown that the effect of a high-frequency electromagnetic field on paper appears as a decrease
in the structural ordering of the material and a change in the shape of the indicatrix of the reflected radiation power from
an He-Ne laser at the wavelength 632.8 nm, a decrease in the bidirectional reflection and transmission coefficients of the
paper. We have established that when the force lines of the magnetic component of the high-frequency electromagnetic field
are oriented perpendicular to the plane of the sheet of paper, we observe a more substantial decrease in the anisotropy in
the surface layer and within the interior (the volume) of the paper than when the lines of force are oriented parallel to
the plane of the paper.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 421–426, July–August, 2007. 相似文献
125.
报道了一种由纤芯直径分别为15 μm和25 μm的大模场光纤组成的全光纤脉冲放大器模块。当注入脉冲宽度为10 ns,重复频率为1 Hz,光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300 μJ。此外,实验研究了该放大器模块输出的时间特性。研究发现:由于受激布里渊散射(SBS)效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值。 相似文献
126.
仿真和实验研究了一种控制Nd:YAG脉冲激光能量通断的光纤直接连接型光开关。建立光纤耦合模型,分析了光纤对准误差中对耦合效率的影响,其中横向偏移的影响最显著。采用微机电系统V型槽固定光纤,微小型凸轮作为制动器,步进电机驱动凸轮旋转,微小型凸轮与移动光纤相切,带动光纤移动,实现两光纤的错开和对准。制造了这种高功率直接连接型光纤光开关原理样机,并进行了主要性能测试。测试结果表明,这种光开关能够满足激光点火系统的大容量、高隔离度的要求。 相似文献
127.
128.
129.
The far infrared transmittances and Faraday rotation effect in one-dimensional photonic crystals that contain magnetic microcavities are calculated with the transfer matrix method. The different stacking sequences of dielectric layers in the magnetic photonic crystal are considered in this paper, and the linewidths of transmission peaks and localised light of the photonic crystals are discussed. The enhancement of Faraday rotation is presented in the magnetic photonic crystals, and the largest rotation angle at the frequency of the transmission peak is 29 °mm−1, which is larger than previous results. 相似文献
130.
In this paper the gain characteristics of two-pump fiber optical parametric amplifiers (FOPA) with two-section highly nonlinear fibers are analyzed numerically and the parameters of the fibers are optimized to reach broad and flat gain spectra using genetic algorithm. Different from the previous methods, here the space between two pump wavelengths and the parameter β4 of the fibers are included as a pivotal factor in the optimization. The numerical simulation shows that using two-section practical high nonlinear fibers, the amplifier may reach 110 nm bandwidth covering 1495–1605 nm with 10.5 dB average gain and gain ripple of 0.17 dB, when the total pump power is 1 W. 相似文献