Comparison of a pyroelectric detector with a Tungsten-Carbon point-contact diode. Application to the measurement of temporal coherence of an HCN laser

Abstract

The characteristics of a TGS pyroelectric detector and a tungsten-carbon point-contact diode are compared. In direct detection, at an MF of 450 Hz, their voltage responsivities are 200 VW −1 and 130 VW −1, respectively. Their NEP H are of the order of 10 −10 WHz −1 when they are used in the heterodyne detection scheme with the 337 μm HCN laser radiation, at an IF of 366 kHz and a local oscillator power of 50 mW. By doubling this latter, NEP H down to 10 −12−10 −13 WHz −1 could be obtained. The study of beats between the fundamental modes of two identical waveguide HCN lasers led to a temporal coherence ranging from 2.5 × 10 −5 sec to 10 −4sec, depending on discharge parameters.