Abstract

In the past few years techniques of passive mode locking by intracavity optical Kerr effects have rapidly advanced. They are now important methods for generating ultrafast laser pulses. Because in these methods the pulse shortening effect is proportional to the peak intensity, the mode locking process accelerates once an initial pulse of significant peak intensity is formed. On the other hand, mode locking may not selfstart from a cw state because initially the pulse shortening effect is extremely weak, and in cw lasers there are intrinsic pulse broadening effects which maintain the amplitude stability. Understanding the selfstarting conditions for passive mode locking is not only scientifically interesting, but also of practical value for future development of passive mode locking lasers.

© 1994 Optical Society of America