Amplified spontaneous emission spectrum at the output of a diode amplifier saturated by an input monochromatic wave

Expressions for the amplitudes of amplified spontaneous emission waves in a diode amplifier near the frequency ω₀ of a 'strong' input monochromatic wave have been derived in terms of a random function of a stationary Gaussian process. We have found expressions for the spectral density of the amplitudes and shown that, on the red side of the spectrum with respect to frequency ω₀, spontaneous emission waves obtain additional nonlinear gain, induced by the strong wave, whereas on the blue side of the spectrum an additional loss is induced. Such behaviour of the amplitudes of amplified waves agrees with previous results.