Repetition-rate multiplication in actively mode-locked fiber lasers by higher-order FM mode locking using a high-finesse Fabry–Perot filter

Abstract

We demonstrate an FM mode-locking technique for multiplying the pulse repetition rate of lasers by several times above the modulation frequency. The mode locking of the laser is based on the generation of higher-order FM sidebands by an intracavity phase modulator and the periodic selection of the sidebands by an intracavity high-finesse Fabry–Perot filter at spacings of free spectral range which is a harmonic of the modulation frequency. We show the generation of stable, uniformly spaced, equal amplitude optical pulses from a fiber ring laser with two-, three-, and fourfold enhancement in the repetition rate.