2.8-MU-M LASER-PUMPED TYPE-I AND TYPE-II TRAVELING-WAVE OPTICAL PARAMETRIC GENERATOR IN GASE

Ultrashort pulses of a mode-locked Er:Cr:YSGG laser (lambda = 2.8 mu m ) were used to pump travelling wave optical parametric generator (OPG) based on GaSe crystal. Type II wave synchronism OPG was achieved for the first time, giving continuous tunability in the range of 3.9-10 mu m and a typical linewidth of 20-30 cm(-1). Type I parametric generati on was characterized by a broader line, especially near degeneracy, wh ere the linewidth reached 650 cm(-1), and broader tunability, in the r ange of 3.5-14 mu m. For a 10 mm long GaSe crystal travelling OPG pump threshold was 4 GW/cm(2).