Abstract

Frequency combs generated by mode-locked Ti:sapphire lasers have revolutionised optical frequency metrology but are limited by laser gain bandwidth. Broader combs have been generated by coherent combination of combs from spectrally distinct lasers¹ requiring complex synchronization of repetition rates. The Ti:sapphire-pumped femtosecond optical parametric oscillator (OPO) has the advantages of being intrinsically synchronized with its pump and generating multiple tunable sum-frequency mixing (SFM) outputs spanning a very broad spectral range. Previous research has demonstrated relative locking between the pump and OPO output combs, without stabilising the comb interval or absolute position (offset).² We report what we believe is the first OPO-based composite frequency comb, fully stabilised against an external reference.

© 2007 IEEE