A far-infrared broadband (8.5-37 mu m) autocorrelator with sub-picosecond time resolution based on cadmium telluride

A background-free autocorrelator has been developed for measuring the durat ion of far-infrared laser pulses in the spectral range from 8.5 to 37 mum b y using an 840-mum-long wedged cadmium telluride crystal as the second-harm onic generator. Typical intensity second-harmonic autocorrelation traces ar e given for the wavelengths of 19.7 and 37 mum, indicating FWHM pulse durat ion of 0.90 and 1.5 ps respectively. An interferometric autocorrelation tra ce at 18.2 mum has been measured for the first time, and the distortion of autocorrelation traces due to the absorption and re-emission of ambient wat er vapor is shown at 28 mum. (C) 2001 Elsevier Science BN. All rights reser ved.