title: Diffractive broadband coupling into high-Q resonant cavities.
abstract: Optical resonators with high-quality factors (Q-factor) constitute the main building block for many photonic devices capitalizing on light-matter interactions, ranging from light emitters to biochemical sensors. While a high Q-factor enhances light-matter interactions, it also limits the device operation bandwidth. Here we propose and numerically analyze a generic coupling scheme to overcome the apparent trade-off. By using an orthogonal grating, broadband optical coupling into high-Q cavities of diverse geometric configurations can be achieved. As an example, the approach is applied to demonstrate over a 28-fold optical absorption enhancement across a 150 nm band around 900 nm wavelength in single-layer graphene embedded inside a Fabry-Perot cavity.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Lin
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Sun
authors.forename: Jifeng
authors.initials: J
authors.lastname: Liu
authors.forename: Juejun
authors.initials: J
authors.lastname: Hu