引入随机包层的圆柱波导随机激光研究

发布时间：2018-05-06 01:13

本文选题：随机激光器 + 随机激光　；参考：《电子科技大学》2016年硕士论文

【摘要】：在传统的激光腔中,散射和无序结构是无法避免的,虽然不利于激光的产生,但是却可以实现随机激光。传统随机激光的高激光阈值和无方向性限制了其应用。与传统随机介质相比,光纤的波导结构可限制光径向散射,实现高效的、低阈值的定向随机激光输出；此外,不同的光纤波导可提供便利、丰富的放大(如拉曼泵浦、稀土离子吸收能级泵浦)和反馈机制(如瑞利散射和光栅反射),是我们研究随机激光的极佳平台,也为随机激光的优化和调控提供了灵活手段。基于以上的原因,本论文提出了一种新型的光纤波导结构——引入随机包层的圆柱波导结构,通过在毛细管内表面涂覆无序层,并将增益介质(激光染料)溶液填充在纤芯,实现了低阈值、可调谐的随机激光。增益和散射分离,构成稳定的激光器结构。具体内容如下所述：首先,通过软件仿真设计的新型波导结构完成理论仿真,分析模场和功率特性,完善随机激光特性分析,优化实验参数。证明了引入随机包层的圆柱波导结构支持多模传输。另外,随机散射层的无序度越高,波导结构束缚光子的能力越强。其次,详细介绍了引入随机包层的圆柱波导随机激光器的制作。我们需要制作特殊的光纤。利用现有的空心毛细管和混有散射颗粒的粘合性溶液制成特定的随机谐振腔,作为填充增益介质的载体。选择罗丹明B作为增益介质,设计增益控制装置,完成随机激光的实验系统。然后,引入随机包层的圆柱波导随机激光器激光特性研究。改变泵浦照射的位置或者改变增益介质的浓度,可以实现不同波长的激光输出。移除新型的波导结构中的散射颗粒,只有荧光,没有任何激射现象。在这种光纤型光学结构中,随机包层提供多重散射将大部分光限制在增益区,促进随机激射模的形成。系统提供一个开放的通道,能够灵活选择填充材料和散射机制。最后,光纤型随机激光器的输出功率对微流中散射体浓度敏感,在光传感领域存在潜在的应用。增益介质中散射颗粒浓度影响激光的输出强度,随着增益介质中散射颗粒浓度的增加输出激光强度呈指数下降,提出了一种微小颗粒浓度的探测方法。
[Abstract]:Scattering and disordered structures are unavoidable in conventional laser cavities, which are not conducive to laser generation, but random lasers can be realized. The high laser threshold and directionality of traditional random lasers limit its application. Compared with the conventional random media, the waveguide structure of the fiber can limit the radial scattering of light and achieve high efficiency, low threshold directional random laser output. In addition, different fiber waveguides can provide convenience and rich amplification (such as Raman pumping, etc.) The rare-earth ion absorption level pumping and feedback mechanisms (such as Rayleigh scattering and grating reflection) are excellent platforms for the study of random lasers and provide a flexible means for the optimization and regulation of random lasers. Based on the above reasons, a novel fiber waveguide structure is proposed in this paper, which is the cylindrical waveguide structure with random cladding layer, which is coated with a disordered layer on the inner surface of the capillary tube and filled with the gain medium (laser dye) solution in the fiber core. A low threshold, tunable random laser is achieved. The gain and scattering are separated to form a stable laser structure. The main contents are as follows: firstly, the new waveguide structure designed by software simulation is simulated theoretically, the mode field and power characteristics are analyzed, the random laser characteristic analysis is improved, and the experimental parameters are optimized. It is proved that the cylindrical waveguide structure with random cladding supports multimode propagation. In addition, the higher the disorder of random scattering layer, the stronger the ability of binding photons in waveguide structure. Secondly, the fabrication of cylindrical waveguide random laser with random cladding is introduced in detail. We need to make special fibers. A special random resonator was prepared by using the existing hollow capillary tube and the adhesive solution mixed with scattering particles as the carrier of filling gain medium. Rhodamine B is selected as gain medium and gain control device is designed to complete the experimental system of random laser. Then, the laser characteristics of cylindrical waveguide random laser with random cladding are studied. Laser output at different wavelengths can be achieved by changing the position of the pump irradiation or the concentration of the gain medium. The scattering particles in the new waveguide structure are removed only by fluorescence without any excitatory phenomena. In this type of optical structure, the random cladding provides multiple scattering, limiting most of the light to the gain region, thus facilitating the formation of random stimulated modes. The system provides an open channel for flexible selection of filling materials and scattering mechanisms. Finally, the output power of the fiber random laser is sensitive to the concentration of scatterers in microflow, so it has potential applications in the field of optical sensing. The laser output intensity is affected by the concentration of scattering particles in the gain medium. With the increase of the concentration of the scattering particles in the gain medium, the output laser intensity decreases exponentially. A detection method for the concentration of small particles is proposed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN248

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