Single-longitudinal mode operation of a semiconductor laser using a metal film reflection filter

Theoretical and experimental results are presented which show that a narrow-band reflection filter can be used for longitudinal mode selection in semiconductor lasers. Single-mode operation of 13 μm InGaAsP semiconductor lasers both under CW and pulsed operation has been demonstrated. CW mode discrimination of >30 dB has been obtained up to an output power of ∼10 mW. These results suggest a new scheme for single-mode injection laser sources.