A semiconductor optical amplifier with a reduced noise figure
A semiconductor optical amplifier 100 comprises an input for receiving the optical signal 102 and an output for outputting an amplified version of the optical signal. A semiconductor active medium 107 defines an amplification path between the input and the output for amplifying the optical signal as it propagates along the amplification path. A control means co-operable with the active medium selectively controls the amplified spontaneous emission (ASE) of the semiconductor optical amplifier by varying the carrier density along the amplification path. The control means may comprise a laser cavity orthogonal to the amplification path which incorporates only a part of the amplification path near to the output end and and clamps the carrier distribution within the laser cavity to a predetermined gain value, or a resistor network (205; fig 8) for pumping discrete regions of the active medium with current of varying levels.
LANDAIS PASCAL [IE]; SURRE FREDERIC [GB]
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