Gain clamped optical amplifier

摘要

The gain provided by an erbium amplifier (3) is stabilised by spectrally selective optical feedback (4, 5) to make the amplifier lase. The resulting laser emission is extracted from the amplifier output using a Mach Zehnder (8, 9, 10, 11) with matched Bragg reflectors (12, 13) in its two interference arms. The extracted light may be used for supervisory purposes. Part of the laser cavity defining feedback may be provided by the Mach Zehnder by arranging one of its Bragg reflectors to be displaced with respect to the other. <IMAGE>