QPM超连续谱激光光源的研究

This project is based on our previous results supported by "863" project, aims to realize high efficient solid-state near/mid infrared (1.35-5 micro) super-continuous laser by adopting quasi-phase matching technique and optical parametric oscillations. This laser will be implemented by utilizing Mg-doped SLT as the nonlinear crystal with fan-shaped periodic domain structure, shaping the 1064nm pumping laser beam into a flat one, or directly taking usage of slab laser, to achieve the continuous laser output from near to middle IR with the aid of gradual periods of the fan-shaped domain. This scheme combines the advantageous of matched lateral width of OPM supperlattice and the required output beam shape, which is helpful to realize the high power and super-continuous spectrum of the output. This scheme further overcome the shortcoming of the low modulation speed of traditional QPM process, and maximizes the use of the cross-section area of the supperlattice. This laser suggests broad application potentials in both the civilian areas, such as the linear and nonlinear spectroscopy, biomedical, confocal microscopy, high-precision optical measurement, atmosphere detection, and the military area, such as spatial laser confrontation, broadband spectroscopy, and laser radar.

本课题是在 "863"研究成果和所形成的知识产权基础上，采用准相位匹配技术，通过光学参量振荡过程，实现高效全固态近、中红外（1.35-5 微米）超连续谱输出激光器。该激光器以掺镁化学计量比钽酸锂光学超晶格为非线性变频晶体，采用1064纳米激光器为泵浦光源，变频晶体设计为扇形周期结构，将泵浦光整形为扁平形截面，或直接使用板条激光器直接泵浦，利用扇形结构中的渐变周期实现从近红外到中红外的超连续谱同时输出。该方案充分利用了QPM超晶格材料横向宽度，又利用板条激光器输出光斑特点，可实现大功率红外输出；采用扇形周期结构可实现超连续谱输出。该方案克服了QPM调谐速度慢的缺点，最大限度利用了超晶格材料的截面积，具有大功率和超连续谱输出的优点，该激光器在线性和非线性光谱学研究、生物医学、共聚焦显微分析、高精密光学测量、大气环境监测等民用领域和空间激光对抗、宽谱光探测与激光雷达等军用领域具有广阔市场前景。

超连续谱（ｓｕｐｅｒｃｏｎｔｉｎｕｕｍ，ＳＣ）是激光领域最活跃和最富创造性的分支　之一，超连续谱光脉冲以其光谱覆盖范围宽、应用灵活使得许多研究都以其作为重要工具，带动了许多相关学科的发展和进步，促使许多交叉边缘科学的产生，是当今光电子技术研究领域中最前沿的研究课题之一。本项目通过设计研制扇形MGO:SLT光学超晶格，通过皮秒同步泵浦技术，获得了高功率、超短脉冲的皮秒中红外激光，可用于激发光纤、石英等材料获得SC谱；通过光纤激光器泵浦扇形超晶格，获得了宽调谐（1.5um-4um）的中红外光源，并观察到了频率梳现象；通过高功率板条激光器泵浦扇形超晶格构成的光参量振荡器，获得了在中红外波段（1.5um-4um)超过1000nm的SC超连续谱。本项目为新型超宽带、中红外、高功率SC谱的产生奠定了坚实的基础，产生的中红外频率梳、SC谱可用于进行气体分析、谱线标定等应用。