High-power self-similar amplification seeded by a 1GHz harmonically mode-locked Yb-fiber laser

We demonstrate 1 GHz, 75W, 65 fs pulse generation through chirped-pulse and self-similar amplification of a second-harmonic mode-locked Yb fiber oscillator. To confirm the experimental results of a chirped-pulse pre-amplifier, a theoretically calculative model is designed to simulate gain narrowing in the amplification. Specifically, the Kelly sidebands generated by a seed laser experience similar evolution under both conditions. The grism-based self-similar amplifier together with a high-efficiency grating compressor contribute to high-power ultrashort pulses whose spectra are efficiently broadened to a maximum 10 dB bandwidth of 56nm with a center wavelength of 1032.2nm owing to self-phase modulation in a gain fiber.