Abstract

Generation of very high repetition-rate, over 100 GHz, of femtosecond pulses is one of intensively explored targets in the present-day ultrafast optoelectronic research field. Usual passive mode-locking schemes which depend on rather mild saturable absorber actions of such as the NALM (Nonlinear Amplification Loop Mirror) configuration can generate hundred to several-hundred femtosecond pulses, but only at low repetition-rate, say at several-ten MHz. In the NALM configuration, its nonlinear response as a saturable absorber depends on a onetime interference between two mutually counterpropagating waves in the NALM loop. To raise the repetition frequency, enhancing the saturable absorber action might be a great assistance. We proposed before the Q-switching action of coupled non-linear fiber resonators and its application to the mode locking.¹ The saturable absorber action is steepened due to multi-folded field intensity in a resonator configuration and hence the repetitionrate of the formation of solitons inside a resonator can be increased. Here we report the experimental verification of a high repetition-rate capability of the Q-switch mode locking scheme mentioned above.

© 1995 IEEE