Watt-level multi-gigahertz-repetition-rate femtosecond optical parametric oscillator

A watt-level multi-gigahertz (GHz) repetition-rate femtosecond optical parametric oscillator (OPO) synchronously pumped by a GHz-repetition-rate Kerr-lens mode-locked Yb:CYA laser is demonstrated in this letter. The output signal had a wavelength tuning range from 1.41 to 1.64 μm, a maximum average power of 1.58 W, a minimum pulse duration of 139 fs, and a repetition rate of 1 GHz, while the mid-infrared idler had a wavelength tuning range from 2.8 to 4.0 μm, a maximum average power of 1 W, a minimum pulse duration of 103 fs, and a repetition rate of 1 GHz. Through increasing the cavity length of the OPO by a unit fraction of the cavity length of the pump source, the output signal with repetition rates of 2, 3, and 4 GHz was obtained, respectively, and the output power of each was above 1 W. This work represents the highest, to the best of our knowledge, power of GHz femtosecond OPOs.