Abstract

Although semiconductor lasers are inherently large-linewidth and low-power devices, these limitations can be overcome by coupling their output to another laser or resonator. A coupling delay, however, is known to cause an extreme loss of coherence for a self-coupled diode laser above a critical coupling level.¹ Unstable operation has also been observed recently in a system of two semiconductor lasers mutually coupled at a distance,² a phenomenon referred to as overcoupling. In this paper, systematic spectral and coherence measurements are described for a single, self-coupled diode laser and two mutually coupled lasers, demonstrating extreme dynamic instability at moderate coupling levels.

© 1992 Optical Society of America