Intermodulation Distortion in Optical Amplifiers from Carrier-Density Modulation

We present a theoretical model describing the generation of intermodulation products (IMPs) in semiconductor optical amplifiers by signal-induced carrier-density modulation. The IMPs depend strongly on the linewidth-enhancement factor and the ratio of input power to the saturation power of the amplifier. Calculation of the total intermodulation penalty for multichannel amplifier applications is possible using expressions presented.