Generation of ultrabroadband femtosecond pulses in the mid-infrared by optical rectification of 15 fs light pulses at 100 MHz repetition rate

Quasi-single-cycle near-infrared light pulses with a measured spectrum extending from 7 to 15 μm have been generated, opening up new perspectives in IR spectroscopy. The method is based on the rectification of 0.8 μm 10–15 fs light pulses from a 100 MHz oscillator, using the instantaneous second-order polarizability of bulk semiconductors such as GaAs.