基于新型瑞利散射效应的多波长窄线宽光纤激光器机理研究

This project is proposed based on the practical requirements on multi-wavelength narrow-linewidth laser sources in various fields, including coherent optical communications, optical measurements and sensing, the generatino of microwave or Terahertz wave et al. In the project, the new Rayleigh scattering will be employed as the foundation of two key mechanisms to achieve the narrow linewidth for multiple wavelength lasers simultaneously. .1). The first one is the linewidth narrowing process based on ultr-narrow gain bandwidth of stimulated Rayleigh scattering (STRS) process on the fiber. ①.The basic operation principle is as follows: The multiwavelength light sources with MHz-level linewidth are amplified and then injected into the proper fiber medium.With the STRS's linewidth narrowing effect, the linewidth is compressed to kHz-level. ②. The involved research contents include: the physical mechanisum of STRS's narrow gain bandwidth; the modeling and characteristics analysis of STRS under distributed feedback; the performance study of linewith narrowing under multiwavelength input. .2). The other is the mode selection mechanism based on Rayleigh scattering effect. ①. With the rayleigh-based mode selection mechanism applied in multi-wavelength fiber laser, the single-longitudinal-mode and the consequent linewidth can be obtained. ②. The main research include the physical process of Rayleigh-based side-mode suppression, the modeling of distributed multiple Rayleigh scattering effect, the cooperative characteristics under the Rayleigh-based mode selection and gain competition suppression. .Finally the novelties of this proposal include: New fiber-based Rayleigh scattering effect, its application for implementing kHz-narrow-linewidth fiber laser systems with two or more wavelength output, the potential of providing the candidate scheme of multi-wavelength narrow linewidth light source for various application fields.

本项目以相干光通信、测量与传感、微波/THz波领域对多波长窄线宽光源的需求为立项背景，基于光纤介质上新型瑞利散射效应，提出并研究适合在多波长条件下取得kHz量级窄线宽的关键机理及技术。.1)瑞利散射的线宽压窄机理：①将MHz量级线宽的多波长光注入光纤，在超窄瑞利增益的作用下线宽被压窄至kHz量级，②主要研究光纤介质下瑞利散射增益带宽压窄的内在机理、光分布反馈下的瑞利受激散射模型、多波长条件下线宽压窄性能。.2)瑞利散射的选模机理：①把瑞利散射选模机理引入多波长光纤激光器中，取得单纵模工作及窄线宽性能。②主要研究瑞利窄带增益抑制边模的机理、分布式多重瑞利散射特性与建模、选模机理与增益竞争抑制协同工作特性。.本项目特色在于瑞利散射新机理、基于该机理的多波长但不限于双波长的kHz线宽光纤激光器方案、及该方案在相关领域内的潜在应用前景。

多波长窄线宽激光器在精密测量、光学传感、THz/微波光子学领域有着广阔的应用前景，本项目提出使用光纤媒介散射效应来获得可调谐、多波长、窄线宽的光纤激光器方案，利用瑞利散射作为分布反馈镜，同时辅以多种技术手段（布里渊散射、复合腔、自写入FBG），成功实现可调谐多波长单纵模激光输出。本项目对提出的技术方案进行了理论分析和实验验证，比较系统地研究了所提出激光器技术方案中的影响因素和性能指标，主要完成如下工作内容和成果。1、从理论和实验方面分析光纤媒介布里渊和瑞利散射效应，包括布里渊阈值和增益特性、受激布里渊抑制技术、瑞利散射测量等；2、实验搭建延时自外差法测量激光线宽装置；实验试制了拉锥光纤作为分布反馈介质；3、利用瑞利分布式反馈介质，联合复合腔和基于饱和吸收体，成功实现可切换双波长和单纵模工作激射状态，输出线宽达到项目预期目标，饱和吸收体有助改善输出波长和功率稳定性，复合腔有助于抑制边模，瑞利散射效应可有效压窄输出激光线宽；4、利用拉锥光纤媒介的受激布里渊效应并结合多腔体选模机理实现多达12条多波长激射并实现单纵模工作状态；5. 发表标注基金资助的SCI/EI收录论文14篇，申请中国国家发明专利3项。