80-MHz difference-frequency generation of femtosecond pulses in the mid-infrared using GaS0.4Se0.6

We employ GaS 0.4 Se 0.6 nonlinear crystal for difference-frequency generation between the signal and idler pulses of a synchronously pumped femtosecond optical parametric oscillator at 80 MHz achieving continuous tuning from 4 μm (>12 mW) to 12 μm (>0.5 mW) with almost bandwidth limited mid-infrared pulses of ∼200 fs full width at half maximum.