Automated laser heterodyne optical/microwave spectrum analyzer

Abstract

The monolithic diode-laser-pumped unidirectional single-mode Nd:YAG ring laser has extraordinary properties of coherence and frequency stability. Reported is the use of a pair of such lasers voltage controlled by a PC-AT computer to frequency scan the laser frequency and the heterodyne frequency between the lasers in an automated fashion. An IEEE-488 bus interface to an HP8566B spectrum analyser is used to provide computerized data acquisition of heterodyne frequency (and, thereby, change in tuned laser frequency) and heterodyne power. This automated heterodyne instrumentation has been applied in a straightforward fashion to the characterization of the absolute frequency response of individual infrared detectors over the DC-to-24-GHz calibrated power range of the spectrum analyzer.<>