Abstract

Fiber lasers can generate an optical pulse train that can be used as a source in optical communication systems. However, the repetition rate of fiber laser is low due to the long length of the cavity of a fiber laser. Recently, many research groups have been reported the possibility to use the fiber laser as the source of more high bit rate communication system.^1,2 These use an actively harmonic mode-locking¹ or a hybrid method, which is consisted of actively mode-locking and passively mode-locking² in order to stabilize the pulse train and equalize the amplitude of each pulse. However, sometimes in a passively mode-locked fiber laser harmonic mode-locked pulse trains were reported as a form of partial harmonic mode-locking, which has a bunch of multiple pulses in a cavity.³ The understanding of mechanism of multi-pulse formation is very important to generate the harmonic mode-locking or in order to understand the dynamics of passive mode-locking. These multi-pulses can build up a perfect harmonic mode-locked pulse train by changing cavity parameters. The passively mode-locked fiber laser has more advantages for the generation of ultra short pulses.

© 2002 Optical Society of America