We demonstrate numerically a novel passive mode-locking mechanism for semiconductor lasers based on nonlinear directional coupling. In a designed ring cavity a long pulse can be compressed in the bar port of the directional coupler as a result of linear coupling and gain saturation. Meanwhile, a pulse with a shorter pulse width and a higher pulse energy emerges from the cross port. Hence we can use the cross port as the output coupler of the laser system, leading to an output pulse energy that is greater than the intracavity pulse energy.
© 1996 Optical Society of America
Chih-Wei Hsu and C. C. Yang, "Passive mode locking of semiconductor lasers based on nonlinear directional coupling," Opt. Lett. 21, 878-880 (1996)