Numerical Simulation of Ring Cavity Wavelength-Swept Laser Based on Semiconductor Optical Amplifier

A numerical model of a ring cavity wavelength-swept laser based on semiconductor optical amplifier (SOA) is described. In this model, the SOA is restricted by a carrier density rate equation and set of traveling wave equations, which describe the amplified signal and spontaneous emission photon rates. In addition, fiber Fabry-Perot tunable filter, which is used to select the transmission wavelength, is modeled by a multibeam interference transmission function. Thereafter, a coupler, which outputs and feedbacks the laser is simply described by its splitting ratio. Finally, an isolator is idealized to ensure unidirectional lasing. By numerically solving the model, the spectra evolution, carrier density, signal, and amplified spontaneous emission forward and backward distributions along the transmission direction, the output power versus filtering center wavelength, injection current, and coupling ratio were studied, respectively. The results are used for deeply understanding the kinetic process of such swept laser and predicting the sweep range, the bandwidth, the output power, and the threshold current of the laser.