Compression of tunable broadband mid-IR pulses with a deformable mirror pulse shaper

To improve the utility of ultrafast infrared spectroscopy experiments, we have developed and actively compressed a tunable broadband mid-IR (BBIR) source. The octave-spanning BBIR source is generated by a filamentation process of 800 and 400 nm pulses in a pressurized gas cell. To correct the higher-order dispersion effects in BBIR pulses, we have introduced a deformable mirror grating compressor, which uses an iterative genetic algorithm with optical feedback. Compression yields nearly transform-limited BBIR pulses of 21 fs, or ∼1.4 optical cycles at the center frequency, as measured by cross-correlation frequency resolved optical gating.