Super-Resolved Bulk States of Photonic Crystals With Cathodoluminescence Microscopy

Progress in photonic crystals (PhCs) enables the advanced manipulation of light propagation, leading to strong light-matter interactions and unconventional applications. To explore the physical nature and realize the precise and efficient control of position-dependent light-matter interactions, the direct deep-subwavelength characterization of PhC states is pivotal. Here, the super-resolved visualization of bulk states in the z-direction asymmetric dielectric PhC is realized by characterizing the radiative local density of optical states, including the etched hole area. An accelerating voltage scanning approach is proposed to selectively probe bulk states and substrates, elucidating the electron-matter interactions affected by the electron-beam energy. The bulk state energy is demonstrated to be confined inside structure holes as shown by the cathodoluminescence intensity mappings of PhCs with different geometrical parameters, enabling the design of a silicon-based high-quality cavity in the visible range. This work provides a deep investigation of the depth-dependent interaction between the electron beam and dielectric PhCs, promoting the characterization of PhC delocalized modes. The deep-subwavelength detail of bulk state benefits the future nanoscale manipulation of light-matter interactions and the optimization of quantum emission devices.