A 10.6-MU OPTICAL HETERODYNE COMMUNICATION SYSTEM

A 10.6-µ optical heterodyne communication system is described that uses two stable single mode and single frequency CO2 lasers of high frequency stability. Wavelength control on both lasers allows the use of one and the same transition of the rotation-vibration band of CO2 around 10.6 p. The system has a bandwidth of 1 MHz, and simultaneous operation in baseband and on a 50-kHz carrier has been achieved. Heterodyne detection with mercury cadmium telluride detectors yielded signal-to-noise ratios within 3 dB of the coherent photon noise limit. © 1969 Optical Society of America.