Chirped pulse amplification of an ultrahigh-repetition-rate Ti:sapphire frequency comb using a tapered semiconductor amplifier.

Abstract

Chirped pulse amplification of a 1.6 GHz Ti:sapphire femtosecond frequency comb was achieved using a GaAs-based tapered semiconductor amplifier. The spectral component of 855-865 nm was coherently amplified up to 379 mW at 2.5 A, corresponding to a peak power of 1.48 kW and an average power of 150 µW per mode. A chirped Bragg grating was used for pulse stretching and compression, resulting in a 150mm×200mm compact amplification system. Competition between the amplified spontaneous emission and the coherent signal was observed at high driving currents. A numerical analysis was presented to account for the observed gain suppression. This amplification method is useful for the realization of high repetition rate frequency combs with a wider spectral range, including the UV and mid-infrared regions.