Cr∶LiSAF飞秒激光器中Gires-Tournois镜的设计  

Design of Gires-Tournois Mirrors Used for Dispersion Compensation in Cr∶LiSAF Laser

作　　者：廖春艳[1] 范正修[2] 邵建达[2] 

机构地区：[1]西北大学物理学系国家级光电技术与功能材料及应用国际科技合作基地,西安710069 [2]中国科学院上海光学精密机械研究所,上海201800

出　　处：《光子学报》2011年第8期1177-1180,共4页Acta Photonica Sinica

基　　金：国家自然科学基金(No.60378005)资助

摘　　要：飞秒激光脉冲的产生主要依赖于激光腔内净的负群延迟色散.但是在固体激光器中,增益介质和其它光学元件却引入了正色散,因此需引入相应的色散补偿机制.布儒斯特角棱镜对曾是激光腔中色散补偿的主要办法,但是它在进行群延迟色散补偿的同时还会引入高阶色散,使激光器操作困难并影响激光器的尺寸和重复频率.Gires-Tournois镜是一种新型的色散补偿元件,可以克服这些缺点.本文介绍了Gires-Tournois镜的基本结构,分析了影响Gires-Tournois镜的群延迟时间、群延迟色散和三阶色散的量,给出了Gires-Tournois镜的设计原则并根据Cr∶LiSAF飞秒激光器中的色散补偿要求设计了性能优良的Gires-Tournois镜.该Gires-Tournois镜在750～900nm的波长范围内具有高于99.9%的反射率和-35±8fs2的群延迟色散.用这样的Gires-Tournois镜经过4次反射后可以补偿3mm的Cr∶LiSAF晶体的绝大部分群延迟色散.Femtosecond-pulse generation relies on net negative intracavity group-delay dispersion.Solid-state gain media and other optical components always introduce a certain amount of frequency-dependant positive dispersion in the cavity,which must be balanced as well.Brewster-angled prism pairs were popular choices in the last years.However,in prism-pair-controlled lasers,higher-order dispersion of the prism pair will be introduced,which increases the sensitivity and affects the size and repetition rate of femtosecond-pulse solid-state laser oscillators of the pulse width to the cavity and prism alignment.Gires-Tournois mirrors may not introduce above defects and can exhibit high reflectivity and precise control of the frequency-dependent group delay over a large bandwidth.They have played and will continue to play an important role in ultrashort pulse laser systems.Basic structure、dispersion performance and principle of design of Gires-Tournois mirrors are discussed.The optimized multilayer mirror used in a Cr∶LiSAF laser is reported.This mirror exhibit high reflectance（〉99.9%） and smooth group delay dispersion（-35±8 fs2） from 750 nm to 900 nm.Most group delay dispersion of a 3 mm Cr∶LiSAF crystal can be compensated by four bounces.

关 键 词：光学薄膜 Gires-Tournois镜 群延迟色散 色散补偿 CR:LISAF激光器 

分 类 号：O484[理学—固体物理]