Dynamic analysis of erbium-doped optically pumped waveguide lasers using a time-domain travelling wave model

Abstract

A simple and straightforward dynamic model of Er³⁺-doped optically pumped waveguide lasers using a time-domain algorithm is developed. The theoretical model is based on (a) time-dependent rate equations of a quasi-two-level system for the population densities and (b) time-dependent travelling wave equations for the pump and signal power which are solved simultaneously in the time domain. In addition, the longitudinal distribution of spontaneous emission noise is also taken into consideration. Using the fast Fourier transform, the spectrum profile of the time-domain signal power is calculated. In this paper, the transient responses of population densities, pump and signal power are investigated for Er³⁺-doped Ti:LiNbO₃ waveguide lasers. To demonstrate the sophistication of this time-domain model, the influence of the cross-coupled effect of the travelling waves due to the optical feedback of an etched grating is also studied. Dynamic response of the waveguide laser with and without a grating are compared.