Noise equivalent circuit of a two-mode semiconductor laser with the contribution of both the linear and the nonlinear gain

An equivalent circuit model of a semiconductor laser diode and its MDS (microwave and RF design systems) implementation are described that allow a straightforward calculation of the noise characteristics of a laser diode combined with electronic components. This noise equivalent circuit model that is derived from the two-mode rate equations including both the self-saturation and cross-saturation contributions to the nonlinear gain and Langevin noise sources demonstrates the influence of the sl demode on the low-frequency relative intensity noise (RIN) enhancement.