Abstract

An effective pulse formation in solid-state lasers is available through the wide variety of resonant and non-resonant optical nonlinearities, e. g. self-phase modulation, nonlinear optical Ken effect and self-focusing. An extremely short pulses have been achieved due to the femtosecond response of these third-order nonlinearities. It was shown that the start of ultra-short pulse generation may be provided by external disturbances of a laser system, for example, by modulation of cavity period, also without the traditional amplitude modulation. It seems that mode locking can be obtained "easier" than one used to think before. Here we have shown that the laser system, with self-phase modulation and energy saturation of losses, potentially possesses a nonlinear mode which can be excited under certain conditions, that results in generation of ultra-short pulse train without usual passive mode locking. This technique is very attractive for use of passive crystalline shutters (such as YAG, GSAG and firsterite) aimed to ultrashort pulse generation in all-solid-state lasers.

© 1996 IEEE