Inverse design couplers for the excitation of odd plasmonic pairs in thin semiconducting films

TL;DR

This paper presents an inverse design approach for grating couplers that efficiently excite odd plasmonic pairs in ultrathin doped indium tin oxide films, advancing semiconductor-based plasmonics.

Contribution

It introduces a gradient descent-based inverse design method to optimize grating couplers for exciting odd plasmonic pairs in thin semiconducting films.

Findings

Optimized couplers significantly improve excitation efficiency.

Three models with different optimization levels are compared.

Results are prepared for experimental validation.

Abstract

A set of grating couplers that convert plane waves into odd pairs of plasmons supported by extremely thin layers of doped indium tin oxide is designed. The inverse design approach is implemented to improve the efficiency of ordinary periodical couplers significantly. The optimization code based on the gradient descent method and direct Maxwell solver is designed in Matlab. Three models with different optimization levels are compared and discussed. The results of calculations are prepared for subsequent experimental verification. Considered odd plasmonic pairs represent an example of high quality modes tunable using a field effect. They are potentially applicable for the implementation in various active electro-optical devices and lead the way to fully semiconductor based plasmonics.