共查询到20条相似文献,搜索用时 140 毫秒
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介绍利用光纤进行分布应变测量的技术。由于光纤适合用于复合材料,所以制成的装置可用于监测大复合基底的结构。这种双芯光纤传感器装置是一根包含两根间隔很近的串扰波导光学丝。用多波长光源照射单个传感器的输入端,用处理装置分析探测器响应传感器输出端发射的光而产生的信号。对于悬臂梁式的弯曲结构而言,传感器输出的傅里叶变换是加在这种结构上的弯矩分布。在传感器信号中还能识别点负载密度。 相似文献
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首次提出了一种基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术, 利用保偏光纤光栅选频产生两个偏振稳定的激光信号, 采用扰偏器确保激光输出的两个正交偏振态功率的一致性, 最后输入高速光电探测器产生微波/毫米波. 通过对保偏光纤光栅施加不同大小的侧向应力, 可以灵活调谐输出的毫米波频率. 实验制作了基于偏振稳定双波长保偏光纤光栅激光器的可调 谐微波/毫米波产生装置, 通过对保偏光纤光栅施加不同的轴向拉力分别产生了20.407 和22.050 GHz的微波信号. 仿真产生了60 GHz的毫米波信号, 并分析该毫米波在光纤无线通信下行链路的传输性能, 结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端, 解调后仍然得到很好的眼图, 充分证明了本方案的优越传输性能. 相似文献
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为了实现光导开关以MHz重复频率运行,设计了通过延迟产生MHz序列重复频率触发光的分光系统。分光系统由多根类蜂窝状排布的光纤组成并分为数组,各组光纤长度不同以产生时间序列。进行了光纤分光系统的理论计算,设计了分组程序,获得了各根光纤的输出端能量占比,实现了光纤输出端的分组设计优化。计算结果表明:当分光系统半径与激光器焦斑之比增大时,分光系统效率增高,达到一定数值后,分光系统效率趋于稳定;当激光器焦斑大小不变时,光纤层数增大,分光系统效率变小;当触发光脉冲数不变时,在一定范围内,光纤层数增大,输出端激光能量的最大相对误差变小。实验结果表明:四脉冲10 MHz分光系统实现了周期为100 ns的4个光脉冲输出,输出端能量最大相对误差6.80%,系统效率为38.07%。 相似文献
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本文研究了高功率激光束通过国产的低损耗光纤的耦合-传输特性。已研制成由透镜-光纤-透镜组成的光纤光缆。通过2米长的石英光纤光缆已能输出200W的激光光束,其辐合-传输效率达90%。到目前为止,已成功地使用光纤光缆进行了六例肝癌手术、一例肝血管瘤手术和一例口腔癌手术。 相似文献
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对光注入情况下混沌光纤激光器的输出特性进行实验研究.混沌光纤激光器采用环形腔结构,利用光纤的非线性克尔效应产生混沌激光.主激光器产生的混沌激光通过光隔离器和光纤耦合器注入到混沌掺铒光纤激光器实现外光注入.将主激光器产生的不同功率的混沌信号注入从激光器,研究光注入后从激光器混沌信号时序、频谱、自相关以及稳定性与复杂度等特性.结果 表明,光注入后的混沌信号时序随机且幅度频数呈高斯分布,频谱无明显的周期特性,自相关特性优良.光注入掺铒光纤激光器混沌输出在保证混沌源高复杂度的同时提高了混沌源的稳定性. 相似文献
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介绍了利用光波在已知长度差的两段不同长度的光导纤维中传输时间延时差测量光速的基本原理。时钟方波信号通过LED调制电路转变为光信号在一段光导纤维中传输,后经SPD再生电路重新转变为方波再生信号,将原始方波信号与再生方波信号同时输入示波器中测量延时τ1,采用相同的方法测量另一端光导纤维传输延时τ2,通过已知的长度差和延时计算出光导纤维中的光速VZ,最终计算出光速c。 相似文献
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We have theoretically and experimentally investigated polarization insensitive of all optical wavelength conversion for polarization multiplexing signal based on four-wave mixing (FWM) in nonlinear optical fiber. Optical polarization multiplexing technique can be used to double the transmission bit rate by adding data on each of two orthogonal optical states. At the receiver side, the two orthogonal signals can be obtained by direct detection. The eye diagrams of the original signals have been probed and compared with the converted one in this experiment. The characteristics of the converted signal have been fully studied and a little crosstalk which leads a better corresponding eye diagram has been obtained after polarization demultiplexing. 相似文献
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Wei Zhang Changlun Hou Yu Geng Guoguang Yang 《Optical and Quantum Electronics》2009,41(14-15):981-988
Closely packed optical fiber arrays are used to increase the scanning speed in some laser scanning systems, but standard optical fibers are shown to be unsuitable for these systems. In this paper, a closely packing technique of micro optical fiber arrays is presented. The fabrication and properties of micro fibers, whose diameters range from several hundred nanometers to several microns, are introduced. These micro fibers are arranged side by side in V-shaped grooves, which are fabricated by photolithography and etching techniques on silicon substrate. Comparing to standard optical fiber arrays, such closely packed micro optical fiber arrays can eliminate the dark area among output light spots and can solve the problem of high accuracy demand of exposure location. This closely packing technique is also proved to be a feasible method in practical scanning systems. 相似文献
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All-fiber wavemeter and Fourier-transform spectrometer 总被引:1,自引:0,他引:1
An all-fiber Fourier-transform spectrometer is proposed and demonstrated, based on the diffraction of light through the side of a standard optical fiber by a UV-induced fiber grating. The interference pattern, whose Fourier transform yields the optical spectrum, is formed by light diffracted from counterpropagating modes in the fiber. The device is simple and compact and functions as a wavemeter, a fiber-optic network monitor, or a tool for fabrication and testing of long fiber Bragg gratings. 相似文献
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Ultrasonic non-destructive testing systems designed to control huge structures normally use several transducers in the reception stage. To avoid increasing the cost of electronics, a multiplexer is used to send all received signals to the same processing module. Traditionally, transmission of such signals is carried out using copper cables. For special applications (i.e. continuous monitoring of nuclear plants) metallic cables are not suitable because of their high sensitivity to electromagnetic perturbations. Moreover, the multiplexing is made electronically. When the distance between the transducers and the reception unit is large and/or electromagnetic noise is important, signal degradation takes place. The proposed system implements the transmission and multiplexing of ultrasonic electrical signals obtained by means of broadband transducers (up to 1 MHz), using an optical fiber. Optical fibers are made of dielectric materials (silica or plastic) so they are inherently passive to electromagnetic noise. Wavelength division multiplexing is utilized for adding channels to the system by means of fiber optic couplers and different light sources. The wavelengths of the optical signals utilized are located far apart in the optical spectrum in order to avoid serious crosstalk in transmission. The limit to the number of multiplexed channels depends on the optical fiber selected, the spectrum of the light sources and the wavelength division multiplexers or couplers utilized. 相似文献