Picosecond resolution, real-time linear detection system for 10-μm radiation

Abstract

A 10-μm detection system based on up-conversion in proustite has been developed for the measurement of subnanosecond pulses of CO2 laser radiation. This has involved the development of a ’’stretched-pulse’’ Q-switched Nd:YAG oscillator which can be synchronized with the output of a transverse discharge CO2 laser. The 1.06-μm radiation generated by this oscillator and the incoming 10-μm radiation pass collinearly through a 0.6-cm-long proustite crystal which is oriented for type II phase matching. An investigation of the bandwidth of the up-conversion process has shown that it should be possible to resolve 10-μm pulses with durations of ∼5 psec. Using an image converter streak camera to record the 0.96-μm sum frequency, the overall performance of the system has been investigated with the aid of a mode-locked CO2 laser operating at a pressure of 12 atm. The results have demonstrated that mode-locked CO2 pulses as short as ∼75 psec can be generated and that the temporal resolution of the complete detection system corresponds to that of the streak camera.