Abstract

The development of coherent optical communications and high precision interferometry requires ultra-narrow linewidth laser sources, and as a result, laser linewidths down to a few kHz have been reported in recent years. The various methods used^1–6 to determine the linewidths of these lasers are all based on the delayed self-heterodyne or self-homodyne technique, originally proposed by Okoshi et al.,¹ in the form of a Mach-Zehnder interferometer. In this form the self-homodyne system requires two fiber couplers and a polarization controller to form the interferometer.

© 1991 Optical Society of America