Distributed feedback laser simulations based on GaInNAs-GaAs single-quantum-well

First and second order DFB-lasers are simulated. For the second order DFB, thin layer theory is applied, i.e. the grating layer is thinner than the wavelength. The theory is based on coupled wave equations and incorporates the Green function method for the calculation of radiating wave. The DFB laser consists of a single quantum well (6-nm Ga_0.66In_0.34N_0.016As_0.984/GaAs) with 150-nm undoped GaAs waveguide layer on both sides of quantum well and an additional grating layer of first or second order. Further, p/n-doped Al_0.3Ga_0.7As cladding layers of 1.5-μm are added. These two DFB lasers have been studied by simulating optical power versus current, delta density and surface wave intensity. Due to increased photon density in the cavity caused by high reflectivity, the spectrum gets broadened in an inhomogeneous manner and causes multimode amplification rendering a spatial hole burning-like effect. The optical distribution and wave intensity are also simulated at different cross-sections. The optical gain is evidently the key feature for this material and its effect on the real index and spectrum is also computed for different N compositions in Ga_xIn_1-xN_1-yAs_y/GaAs. The spectral features at different threshold current levels and reflectivity are simulated. An attempt is also made to compute the temporal properties of the structure.