New Insight Into Complex Mode Matching Method for Modeling and Simulation of Surface-Emitting Grating Couplers

A complex mode matching method is investigated for modeling and simulation of surface-emitting grating couplers. It is noted that the degree of accuracy for the complex modes obtained numerically plays significant role in determining the overall accuracy of the mode matching method, regardless of the number of modes used in the mode expansion. Furthermore, a reduced two-dimensional (2-D) model by using the effective index method is shown to yield highly accurate results in comparison with the full 3-D model for practical grating couplers, which allows huge saving in computational resources for performance simulation and design optimization. Finally, we employ a robust genetic algorithm (i.e., the particle swarm method) for optimization against grating period for maximum coupling efficiency to a single mode optical fiber and produces results consistent with those reported in literature.