Abstract

Laser linewidths have been previously measured using optical fiber circuits where differential fiber paths are much longer than the laser’s coherence length.^1,2 For narrow linewidth lasers, however, these methods require excessively long fiber lengths, and since they yield autocorrelation measurements, they do not provide a direct method for determining whether the laser indeed operates at a single frequency. We demonstrate the use of fiber ring resonators, which may be operated in either a scanning Fabry-Perot mode or a FM discriminator mode, to monitor and measure linewidth characteristics of narrow linewidth single-frequency lasers.

© 1988 Optical Society of America