光纤型随机激光调控机理及实现研究

Fiber random lasers (FRL), which research is the hot spots all over the world, have the advantages of simple structure, high efficiency, and strong ability of linewidth narrowing. However, regulating output of FRL remains a challenge of related research. Finding new way and principle to control FRL, is of great significance to enrich random laser theory as well as to take good use of the unique advantages of FRL. In this project, random distributed Bragg gratings or refractive fluctuation are introduced in the core of special fibers, so as to obtain enhanced feedback and to realize low-threshold and high-efficiency FRL. Then principle and operation law of such FRLs will be studied. Based on this, creative and exploratory study will be done, aiming to solve wavelength and mode uncontrollability of FRL. That is to regulate FRL through one-dimensional optical fiber waveguide structure, stable/dynamical spatial perturbation of a control light, and introducing of a functional external cavity. The purpose is to find new optical controlling method to regulate output of FRL flexibly and precisely, so as to gain breakthrough in realization of wide range tuning of wavelength/bandwidth for modeless FRL as well as mode locking and dynamics control of coherent-mode FRL. The study is suitable for different kind of FRLs, which has guiding significance to extend applications of FRLs in the area of information and sensing.

光纤型随机激光器（FRL），具有结构简单、效率高，强线宽压窄能力等特点，是当前国际研究的前沿热点。然而，其输出的调控问题是该领域面临的一个挑战，如何寻求新的调控机理，对丰富随机激光理论，更充分利用其独有优势，开拓新的应用具有重要意义。本课题基于典型的特种光纤，通过在纤芯引入随机分布的光栅或折射变化，获得增强型的反馈机制，实现高效、低阈值的FRL，并研究其激射机理和规律。在此基础上，针对FRL波长不可调和模式不可控的难题，开展创新性探索，研究光纤一维波导结构，控制光空间动/静态微扰以及引入功能外腔对FRL的调控。旨在发现新光学手段，灵活而精确的调控FRL输出特性，实现无模式FRL的大范围波长/带宽可调谐，以及相干模式FRL的模式锁定和动态控制等突破性进展。研究具有较好普适性，对推动FRL在信息、传感等领域的应用具有指导意义。

在本项目的支持下，项目组成员能够按照计划，围绕光纤型随机激光的理论模型、工作机理和规律以及输出优化及调控这一主线开展研究工作，较圆满地完成了计划内容；实现了对光纤随机激光器建立数值分析体系、揭示其物理机理和获得输出特性及其调控指标等预期目标；同时结合获得的随机激光本身的优势开展了光纤随机激光无散斑成像研究，结合无序结构中的激光调控手段研究了新型波导结构中的光子调控方法，在拓展方向上也有一定突破。主要包括. 提出、设计并实现了随机包层结构光纤随机激光器，有效实现了反馈增强，降低了随机激光激射器阈值，利用该激光器的散射敏感特性实现了微小颗粒浓度及定位测量的传感应用。提出了增益和反馈空间调控方法以及基于种子光的注入锁定方法，实现了相干型光纤随机激光输出模式的选择、功率稳定和准模式锁定。提出了利用混合光纤结构引入高非线性和空间退相干机制，实现了随机激光输出带宽和输出空间相干性的调控，为低噪声、超连续谱产生及无散斑成像应用提供了极佳光源。对低维无序光子结构中的光子局域化及调控进行了探索性研究，为激光在无序结构中的形成、传输等提供了理论指导。