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750~900 nm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.