Numerical simulation of a pulsed laser pumped distributed-feedback waveguided dye laser by coupled-wave theory

A dynamic model of pulsed laser pumped distributed-feedback (DFB) waveguided dye laser based on a coupled-wave theory is described. Due to the periodical distribution of the intensities of pump source and stimulated emission along the waveguide, the rate equations of the population densities are turned into the equations of the Fourier coefficients. Coupled-wave equations of optical fields are used to simulate the laser oscillation. Besides the temporal evolution of the output intensity, the spectra can also be obtained by the Fourier transform of the optical fields. Two different configurations of the waveguided dye laser, prefabricated DFB (mainly index coupling), first- and second-order holographic DFB (dynamic gain-coupling), are considered in the model. The simulation shows that: 1) the temporal waveforms of the holographic DFB consist of sharp spikes; 2) the broadened spectral widths resulted from the possible nonuniformities in propagation constant or grating period are less than 50 pm except for the second-order holographic DFB; and 3) strong parasitic oscillations can be observed in the second-order holographic DFB with terminal reflection. These results and the comparisons of some of them to the experiments are reported.