Abstract

Subpicosecond pulses at wavelengths above 3 μm have been generated until now mainly by difference-frequency mixing whereby nanojoule energy levels have been achieved using high-power femtosecond amplifiers as pump sources (e.g. Ref. 1). In the past few years traveling-wave optical parametric generators starting from parametric fluorescence have been developed as much simpler near-infrared femtosecond pulse sources^2,3 providing substantially higher energies but their tunability has been limited so far to wavelengths not exceeding 3 pm because of the transparency cutoff of BBO and LBO, which are the only crystals resistant to the high peak powers

© 1996 Optical Society of America