基于受激瑞利的激光线宽压缩机制及超窄线宽光纤激光器研究

Stimulated Rayleigh scattering is one of the most important scattering phenomena in the scattering field. It attracted many attentions because of its good characteristics of the frequency and bandwidth since the 1960s. It is possible to research the stimulated Rayleigh scattering and the related applications in advance with the progress of the experimental material and research methods. Based on our previous research results, we propose to realize special optical fiber with the lower threshold value and the larger gain efficient of the stimulated Rayleigh, in which the stimulated Brillouin scattering should be largely suppressed. The enhanced stimulated Rayleigh scattering will have potential applications because of the strong accumulated effect of nonlinear in optical fibers. Because the gain bandwidth of stimulated Rayleigh scattering only depends on the material and the linewidth of pump laser, and is less than that of stimulated Brillouin scattering at least one order, stimulated Rayleigh scattering is one of new mechanism to form optical fiber laser with ultra-narrow linewidth. We propose to study the fabrication and optimize method of ultra-narrow linewidth fiber laser after the laser linewidth compressing mechanism of stimulated Rayleigh scattering is finished.

受激瑞利因其独特的带宽频率特性自20世纪60年代以来得到了国内外学者的广泛关注，但体材料（大体积固体、液体或气体）中因受激瑞利的累积效应较弱而一直得不到较好的发展。因为光纤具有超强的非线性增强和累积效应，申请人提出通过光纤改性和特殊光纤波导结构设计制作来增强光纤的瑞利散射系数和压制受激布里渊散射效应，通过系统研究受激瑞利在特殊光纤波导条件下的增强机制和实验实现条件来制作这种特殊光纤结构，从而使受激瑞利达到可利用的程度。由于受激瑞利的增益带宽比受激布里渊的线宽要低至少一个数量级，而受激瑞利的带宽又只跟材料和泵浦的带宽相关，因此受激瑞利是一种激光线宽压缩方式，即是形成超窄激光的一种新机制。我们将在探索受激瑞利激光线宽压缩机制的基础上，研究一种新的超窄光纤激光器的制作原理及方法。因此通过本项目的研究能为受激瑞利和超窄线宽激光器研究提供新内容，申请人认为该项目的研究具有重要的学术意义和应用价值。

窄线宽激光器由于其极低的相位噪声以及超长相干距离而在长距离传感领域，高精度探测领域等有着重要作用。常规条件下很难将激光器的线宽压缩到百Hz及以下量级。经过4年的研究完成了如下三个任务：(1). 提出基于瑞利散射的激光线宽压缩机制，初步建立了瑞利散射线宽压缩模型；(2). 设计制作基于瑞利窄线宽压缩激光的核心光纤器件（核心器件还需要深入研究其稳定性和可靠性）；(3). 将瑞利散射压窄机制及器件应用于激光器中实现了激光线宽的压缩，并成功将激光器样机应用于分布式传感中。发表SCI收录论文7篇，申请发明专利9项。培养了4名博士生，5名硕士研究生。全面完成了该项目的预期目标，同时课题组也刚申请到了基金委的一个重点基金项目，继续深入开展这方面的研究工作。