Abstract

Despite their relatively long cavity length, fibre lasers can produce pulses at gigahertz rates if they are harmonically mode-locked. Recently, a novel harmonically mode-locked laser that utilizes an asynchronous phase modulator for pulse timing stabilization was reported¹. Significant improvement in repetition rate control was obtained with no need for modulator drive frequency stabilization. Recent reports, on frequency shifted feedback (FSF) lasers, have demonstrated stable pulse operation at fundamental cavity frequency². Such lasers also supported higher-order stable pulses with a repetition rate that in general is asynchronous with the cavity round-trip rime². Here we demonstrate the modified concept of asynchronous pulse timing control in FSF lasers that combines continuous sliding of the laser frequency with pulse trapping by the periodic spectral filter.

© 2000 IEEE