Chirped Pulse Amplification of 1.6 GHz Ti:Sapphire Frequency Comb Using a Tapered Semiconductor Amplifier

Optical frequency combs using GHz mode-locked oscillators have unique advantages compared with typical combs with repetition rates of tens of MHz. The higher optical power per mode makes it possible to measure the optical frequency with a high signal-to-noise ratio. The more widely separated comb teeth enable us to directly resolve the frequency of Doppler-broadened transitions. The compactness is beneficial in practical applications such as astronomical observations. However, the low pulse energy results in less conversion efficiency to the UV region where important electric transitions of nonmetal atoms exist. Coherent amplification of a frequency comb without reducing its repetition rate is necessary to obtain a high conversion efficiency.