PHOTOMIXING AT 10.6μ WITH STRONTIUM BARIUM NIOBATE PYROELECTRIC DETECTORS

Abstract

Theoretical limitations of optical heterodyne detection with pyroelectric detectors are discussed. It is shown that the minimum detectable power P_m of Sr_1−xBa_xNb₂O₆ pyroelectric detectors at 10.6μ, with an intermediate frequency of 1 MHz and a local oscillator power P_L = 1 W is P_m = 8×10⁻¹⁶ W/Hz. An experimental heterodyne receiver with the above conditions is shown to have a value P_m = 1.5×10⁻¹¹ W/Hz where amplifier noise is much larger than detector noise. The theoretical and experimental dependence of P_m on P_L are compared in the amplifier noise limit.