Simulation Analysis Of Wavelength-tunable DFB Laser Based On GaN In Communication Band

The development of optical network technology puts forward higher requirements on the light source of communication system, especially in the next generation of high speed and large capacity of coherent optical communication system. The use of tunable semiconductor lasers can effectively reduce the redundancy, overhead costs and improve network’s flexibility. The tunable distributed feedback (DFB) laser has become the main development direction because of its good performance of single longitudinal mode. A two-dimensional steady physical model was constructed for a GaN semiconductor DFB laser. The feasibility of the physical model was analyzed, which can be helpful to the design of the tunable laser. Meanwhile, the micro actuator was used to realize in the tuning of the laser wavelength.This paper first described the basic principle of the DFB laser. Combined with the coupled wave theory and medium slab waveguide theory, the key structure parameters of the resonant cavity of the DFB laser and the single mode output condition were calculated. Then through the finite element simulation software Comsol, a two-dimensional model of the resonant cavity of DFB laser was established. The influence on laser resonant peak in 1550nm was discussed when changing the structure parameters, which may provide the data to support the design and preparation of the grating.At last, in order to realize the tuning of the laser wavelength, a periodic tunable structures with the mechanical cantilever beam was presented. The cantilever beam is designed to support suspended photonic gratings. With the simulation of single longitudinal mode laser output in the whole C-band, the structure parameters and the relationship between the applied voltage and lasing wavelength have been obtained. The simulation results can provide data support to realize the tuning of the DFB laser wavelength based on MEMS technology.