Feedback-induced noise in index-guided semiconductor lasers and its reduction by modulation

We report a reduction in feedback noise of 15-20 dB by direct modulation of the laser with a 2-5 mA modulation current. The reduction is almost independent of modulation frequency in the frequency range from 50 MHz to 200 MHz, but depends on the external cavity length. The external cavity lengths considered are 5-15 cm. © 1983, The Institution of Electrical Engineers. All rights reserved.