Generation of 20 GHz, sub-40 fs pulses at 960 nm via repetition-rate multiplication

Optical filtering of a stabilized 1 GHz optical frequency comb produces a 20 GHz comb with similar to 40 nm bandwidth (FWHM) at 960 nm. Use of a low-finesse Fabry-Perot cavity in a double-pass configuration provides a broad cavity coupling bandwidth (Delta lambda/lambda approximate to 10%) and large suppression (50 dB) of unwanted modes. Pulse durations shorter than 40 fs with less than 2% residual amplitude modulation are achieved.