空芯Bragg光纤及其在双波长掺铒光纤激光器中的应用

发布时间：2018-07-04 09:53

本文选题：空芯Bragg光纤 + 低折射率差　；参考：《北京交通大学》2017年硕士论文

【摘要】：高性能的多波长光纤激光器在光通信系统、光传感领域有广阔的应用前景。而要在室温下实现性能好、稳定性高、制作容易的多波长掺铒光纤激光器,需要寻找有效的方法抑制掺铒光纤中的模式竞争。空芯Bragg光纤,不同于传统光纤通过全内反射来导光,而是通过包层的周期性结构所引起的带隙效应来导光,因此具有低损耗、色散可控、非线性系数可调等许多优点,在光纤通信、色散补偿、高功率激光传输领域中有着广泛的应用前景。本文以空芯Bragg光纤为突破口,对其开展了深入的理论和实验研究,并基于实际制作的空芯Bragg光纤,将空芯Bragg光纤用于光纤激光器中,实现了掺铒光纤激光器在室温下稳定的单双波长输出,主要工作如下:1、采用传输矩阵法,建立了周期性平板波导的带隙结构理论仿真模型。在验证了该仿真模型准确性的基础上,采用该模型研究了空芯Bragg光纤的结构参数对带隙位置和带隙宽度的影响,仿真结果表明,随着包层数、折射率差的增大,包层限制光的能力逐渐增加,当介质层厚度满足四分之一波长条件时,将得到位于中心波长附近的最大带隙宽度。该理论结果对空芯Bragg光纤的设计和实际制作具有重要的指导意义。2、从空芯Bragg光纤的实际制作工艺和拓展空芯Bragg光纤的实际应用层面出发,提出并设计了具有低折射率差、大芯径的掺锗空芯Bragg光纤。理论研究结果表明:该空芯Bragg光纤带隙位置位于1550nm波段,最低损耗达4.5dB/m,带隙谱为宽带的梳状谱输出,可用作光纤滤波器对输出激光进行调制。3、通过合理的参数设计,提出并设计了具有超宽带、低损耗特性的空芯Bragg光纤。通过增大光纤尺寸,其带隙范围可覆盖到4000nm,带隙区损耗为10-8dB/m量级。该设计在现有制作工艺和制作材料的基础上,实现了在常用传输窗口上的长距离低损耗传输,在光通信系统中有重要应用前景。4、采用化学气相沉积法成功拉制了低折射率差、大芯径的掺锗空芯Bragg光纤,并对实际拉制的光纤进行了参数仿真,结果表明实际光纤在带隙位置上向短波长方向偏移了 5nm,损耗增加了 1dB/m,符合预期设计。5、将空芯Bragg光纤实际应用于光纤激光器中,实现了一种单双波长可切换和可调谐的掺铒光纤激光器,该激光器结构简单,在室温下可实现、稳定的单双波长输出,且边摸抑制比高达50 dB。激光输出稳定性测试表明,在30分钟内,激光波长漂移量均小于O.1nm,峰值功率波动量均小于2dB。
[Abstract]:High performance multi-wavelength fiber laser has broad application prospect in optical communication system and optical sensing field. In order to achieve good performance, high stability and easy fabrication of multi-wavelength erbium-doped fiber laser at room temperature, we need to find an effective way to suppress mode competition in erbium-doped fiber. The hollow Bragg fiber is different from the traditional fiber in guiding light through total internal reflection, but by the bandgap effect caused by the periodic structure of the cladding, so it has many advantages, such as low loss, controllable dispersion, adjustable nonlinear coefficient, etc. It is widely used in optical fiber communication, dispersion compensation and high power laser transmission. In this paper, the hollow Bragg fiber is used as the breakthrough point, and the theoretical and experimental research is carried out. Based on the practical hollow Bragg fiber, the hollow Bragg fiber is used in the fiber laser. The stable single and double wavelength output of erbium-doped fiber laser at room temperature is realized. The main work is as follows: 1. The theoretical simulation model of bandgap structure of periodic planar waveguide is established by using the transmission matrix method. On the basis of verifying the accuracy of the simulation model, the influence of the structural parameters of hollow Bragg fiber on the band gap position and the band gap width is studied by using the model. The simulation results show that the refractive index difference increases with the number of cladding layers. The ability of limiting light in the cladding increases gradually. When the thickness of the dielectric layer meets the condition of 1/4 wavelength, the maximum bandgap width near the central wavelength will be obtained. The theoretical results have important guiding significance for the design and practical fabrication of hollow Bragg fiber. Based on the practical fabrication technology of hollow Bragg fiber and the expansion of practical application level of hollow Bragg fiber, a low refractive index difference is proposed and designed. Large diameter germanium doped hollow Bragg fiber. The theoretical results show that the band gap of the hollow Bragg fiber is located in the 1550nm band, the minimum loss is 4.5 dB / m, the band gap spectrum is a broadband comb spectrum output, which can be used as a fiber filter to modulate the output laser. A hollow Bragg fiber with ultra-wideband and low loss characteristics is proposed and designed. By increasing the size of the fiber, the band gap can be covered to 4 000 nm, and the band gap loss is 10 ~ (-8) dB / m. Based on the existing fabrication process and materials, the design realizes long distance and low loss transmission on common transmission windows, and has important application prospects in optical communication system. The low refractive index difference is successfully drawn by chemical vapor deposition. The germanium doped hollow Bragg fiber with large core diameter is simulated. The results show that the actual fiber deviates 5 nm to the short wavelength direction in the band gap position, and the loss increases by 1 dB / m, which accords with the expected design. The hollow Bragg fiber is applied to the fiber laser. A single and double wavelength switched and tunable erbium-doped fiber laser is realized. The structure of the laser is simple and can be realized at room temperature. The output of single and double wavelengths is stable and the side touch rejection ratio is up to 50 dB. The laser output stability test shows that the wavelength drift is less than 0.1 nm and the peak power fluctuation is less than 2 dB within 30 minutes.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN253;TN248

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