Nonlinear circuit model of laser diodes for large-signal microwave photonic CAD

The laser diode nonlinear equivalent circuit model is developed to be integrated as part of a microwave computer-aided design (CAD) software. Single-mode rate equations are numerically solved using a harmonic balance (HB) simulator to predict performance of laser diodes. The laser diode physical parameters are first extracted by fitting these parameters to the measured I-V, L-I and frequency response curves. Analytically calculated photon densities are employed in the CAD simulation model as seed values for a faster convergence time. The laser diode CAD simulation results compare very well with the large-signal modulation measurements for a DH InGaAsP laser diode. Moreover, the simulated nonlinear behavior of a AlGaAs laser diode is compared against the published measured and SPICE predicted results to assess accuracy of this simulation package. Also, this laser diode CAD simulation achieves a faster convergence speed than other approaches using harmonic balance simulators.