Noise reduction in single longitudinal mode lasers by high-reflectivity coatings

Feedback-induced noise in single longitudinal mode semiconductor lasers was suppressed over a wide range of the amount of the optical feedback light by high-reflectivity facet coatings. A relative intensity noise value was as low as -143 dB/Hz at 3 mW output power under 1 percent of optical feedback in the GaAlAs lasers with high-reflectivity (0.75) facets.