Separation and amplification of Kelly sidebands and main soliton pulse in a 2-μm ultrafast fiber chirped pulse amplifier

Abstract

We theoretically and experimentally realize the complete separation of Kelly sidebands and main soliton pulse by introducing a spatial filter inside a pair of grating in a 2-μm fiber chirped pulse amplifier (CPA). The separated Kelly sidebands are experimentally demonstrated to be manifested itself as an independent pulse in the time domain. The average power of the Kelly sidebands is further amplified from 8 mW to ∼ 3.7 W in the amplifier. The extracted main soliton pulse is amplified from ∼ 80 mW to > 7 W with the shortest pulse duration of 346 fs after anomalous or normal dispersion stretching. With further shaping the soliton spectrum to suppress the spectral narrowing effect, the pulse duration is further shortened to ∼ 200 fs.