Grating couplers for guided Bloch surface waves

Abstract

Photonic crystal ridge waveguides supporting guided Bloch surface waves (GBSWs) are a valuable and flexible platform for the development of integrated optical devices. However, coupling light into a GBSW from a single-mode optical fiber remains challenging. In this work, we study the main issues preventing the efficient excitation of GBSWs using grating couplers, and we present some solutions to increase the coupling efficiency. Our approaches do not require any additional fabrication step and can lead to a significant improvement compared to previous implementations. Further optimization along the lines illustrated in this work may allow one to achieve even larger coupling efficiency.