SURFACE SUM-FREQUENCY MIXING FOR AUTOCORRELATION AND CROSS-CORRELATION OF ULTRASHORT UV AND IR PULSES

Surface sum-frequency mixing is shown to be a valuable tool in determi ning the width and shape of ultrashort ultraviolet and infrared laser pulses. The method is demonstrated to measure LV pulses of 300 fs and IR pulses of about 2.9 ps duration. In cross-correlation set-ups the m ethod is inherently background-free, but background-free arrangements can also be realized for autocorrelation measurements, useful especial ly in the ultraviolet. In the present experiments on GaAs(111) and Pd( 111) a spectral range from 3.3-mu-m to below 200 nm is covered, which certainly can be extended to longer as well as to shorter wavelengths. Due to the small source volume phase-matching is not required.