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

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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.