RESUMO
We report on efficient single-pass optical parametric generation (OPG) of broadband femtosecond pulses in the mid-infrared at 10â MHz by exploiting group-velocity-matched interaction in a 42-mm-long MgO:PPLN crystal. Using a microchip-started femtosecond amplified Mamyshev oscillator at 1064â nm as the pump, the OPG source can provide tunable femtosecond pulses across 1516-1566â nm in the signal and 3318-3568â nm in the idler, with slope efficiencies of â¼93% and â¼41%, respectively. For 650â mW of average input pump power, signal powers of up to 283â mW at 1524â nm are generated, with more than 200â mW over the entire tuning range. Idler average powers of up to 104â mW at 3450â nm, with more than 80â mW across the full range, are also obtained. For input pump pulses of â¼182â fs, the generated signal pulses have a duration of â¼460â fs at 1516â nm. The idler pulses have a typical bandwidth of ≥100â nm over the entire tuning range, and as wide as 181â nm at 3457â nm. The OPG source exhibits excellent passive power stability, better than 0.5%â rms in the signal and 0.6%â rms in the idler, over 1â h, both in Gaussian TEM00 spatial profile with M2 < 1.5.