High-repetition-rate near-infrared noncollinear ultrabroadband optical parametric amplification in KTiOPO4

We report efficient noncollinear optical parametric amplification (NOPA) of ultrabroadband near-IR pulses tunable in the 1.1-1.5 μm range at a repetition rate of 250 kHz. Improved generation of smooth near-IR continua (extending over ~1.0-1.6 μm) at 250 kHz was achieved by weakly focusing ~20% of the 1 W driving laser beam into a sapphire plate with longer focal length lenses than previously reported. Using bulk potassium-titanyl phosphate (KTiOPO(4)) pumped at 800 nm, powers as high as 11 mW (14% pump conversion efficiency) and signal pulse durations as short as 23 fs were obtained after a single white-light seeded NOPA stage.