Finite-Difference Time-Domain Simulations of Surface Bragg Gratings

Bragg gratings are an essential component of semiconductor lasers. One of the most precise methods to calculate an optical response of such a component is the 3D FDTD method. However, due to its computational effort, it is usually not used for the simulation of large structures. Here, we investigate the performance of 2D and 3D Finite-Difference Time-Domain (FDTD) methods for Bragg grating simulations. We demonstrate, that the 2D FDTD method can be used for grating structures of interest, while the 3D FDTD can only be used for short structures up to 500 μm. We show that the 2D simulation results can be utilized to set up an efficient 3D FDTD simulation. We demonstrate that the combination of the 3D FDTD method and the coupled mode theory provides an efficient way of predicting the reflectance of longer Bragg gratings.