Numerical simulation of filamentation induced by waveguide in semiconductor taper amplifiers

The filamentation phenomenon induced by waveguide is analyzed in semiconductor taper amplifiers. The Split-Step Fourier(SSF) method is used for the first time to simulate the optic field propagation character in laser amplifiers, which could obtain waveguide characteristics rapidly. The simulation results show that the SSF method provides highly accurate description for optic field and indicate that waveguide in taper amplifiers would induce extremely filamentation phenomenon if the seed field could not match the taper angle well. Simulation also shows that, for a taper amplifiers, both seed waist width and taper angle should be designed large in order to reduce the filamentation phenomenon induced by waveguide and obtain better beam quality laser output.