Fano resonances for high performance sensing in an asymmetric resonator based on hybrid graphene/dielectric metasurfaces

Improving the performance and sensitivity of metallic sensors is challenging because of the Ohmic loss that occurs for traditional metallic materials. In this work, we optimized a refractive index sensor consisting of graphene and a periodic array of asymmetric Si nanorod units. The sensor was formed by etching an asymmetric pair of nanorods and introducing gaps in the dielectric resonant nanostructures. This confined a large portion of electromagnetic energy into nanoscale hot spots within the gaps. The sensitivity of the sensor increased from 430 to 595 nm/RIU, and the figure of merit increased nearly fivefold from 956 to 4577 RIU−1. The results prove that the gapped dielectric metasurface served as an ideal platform for enhancing the interaction between light and the surrounding medium, making it a promising candidate for high-performance optical sensors.