Optimal Design for the Grating Coupler of Surface Plasmons

Y. Huang

Mathematics Department, University of California, Los Angeles, CA, USA

We present an optimization procedure to optimize the maximum coupling of free space optical wave to surface plasmon. Shape derivative from shape sensitivity analysis is calculated, and the corresponding partial derivatives of the objective functional with respect to finite number of design variables are derived.

An optimal design of the gratings to couple maximum amount of free space photon into surface plasmon wave is implemented by using COMSOL Multiphysics RF Module. The optimization procedure is much better than those traditional ones, because the gradients can be calculated much more accurately. Using a gradient ascent approach, the method converges fast to a local optimal design.