Intensity noise and spontaneous emission coupling in superluminescent light sources

A simple expression for the noise in the photocurrent generated by the detection of light from an ideal superluminescent source is derived using a quantum amplifier model. The excess noise factor X is found to be related to the photocurrent I/sub d/, electronic charge e, spontaneous emission coupling factor K, and full width at half maximum power of the emission spectrum Delta v/sub 1/2/ by the expression X=0.664 I/sub d//eK Delta v/sub 1/2/. Implications of this result for the performance of fiber-optic gyroscopes using superluminescent-diode (SLD) light sources and for the design of low-noise SLDs are discussed.<
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