Accessing Rapidly Scanning Swept Laser Source Instantaneous Spectral Width Using a Multimode Rate Equation Model

In this paper, we present a multimode rate equation model for rapidly scanning swept laser source. The model accounts for the dynamics of a semiconductor-based swept laser source in a ring configuration. The instantaneous spectral width of the laser during sweeping is calculated through wavelength- and time-dependent cavity loss model. The various factors affecting the instantaneous spectral width are studied including the effect of the semiconductor optical amplifier gain spectrum and the filter scanning speed. The model also allows monitoring the evolution of the cavity modes in the time domain as the filter scans. It shows that the instantaneous spectral width is a multifolded property affected by the filter scanning speed and spectral width, the SOA gain spectrum, and other parameters.