Dudley J M, Boussen S M, Cameron D M, Harvey J D
Department of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Appl Opt. 1999 May 20;38(15):3308-15. doi: 10.1364/ao.38.003308.
The intensity and the phase of ultrashort pulses from a self-mode-locked Ti:sapphire laser operating in the vicinity of zero group-delay dispersion (GDD) have been completely characterized by the technique of frequency-resolved optical gating (FROG). For small values of negative GDD, the appearance of a dispersive wave in the pulse spectrum is manifested in the measured FROG trace, and pulse retrieval directly shows its association with a broad leading-edge pedestal. For positive GDD, we confirm previous experimental observations of picosecond pulses with large positive chirp and report a new operating regime in which the output pulses are of picosecond duration but are intensity modulated at 20 THz. The physical origin of this modulation is discussed by analogy with similar effects observed during pulse propagation in optical fibers, and the experimental results are compared with a model of intracavity four-wave mixing about the cavity zero GDD wavelength.
通过频率分辨光学门控（FROG）技术，已全面表征了在零群延迟色散（GDD）附近运行的自锁模钛宝石激光器产生的超短脉冲的强度和相位。对于较小的负GDD值，脉冲光谱中色散波的出现体现在测量的FROG迹线上，并且脉冲检索直接显示了它与宽前沿基座的关联。对于正GDD，我们证实了先前关于具有大正色散的皮秒脉冲的实验观察结果，并报告了一种新的工作模式，其中输出脉冲持续时间为皮秒，但强度以20太赫兹进行调制。通过与在光纤中脉冲传播期间观察到的类似效应进行类比，讨论了这种调制的物理起源，并将实验结果与围绕腔零GDD波长的腔内四波混频模型进行了比较。
