Nonlinear polaritons in a monolayer semiconductor coupled to optical bound states in the continuum

摘要

Schematic of a photonic crystal slab (PCS) sample, with Ta O bars on a SiO /Si substrate, illuminated with TE-polarized light near normal incidence. SEM image of the PCS sample. Calculated TE-mode electric field distribution at /  = 0.024. Schematic of the photonic band structure for TE modes, with the at-Γ optical BIC position indicated with an . Experimental differential angle-resolved reflectance spectra showing one symmetric and two antisymmetric modes. Wavevector-dependent peak position (black) and amplitude (red) extracted using Fano-like fits for the antisymmetric mode near the BIC location; blue squares show the peak positions shifted owing to a 9 nm hexagonal boron nitride (hBN) layer. Extracted wavevector-dependent linewidth (black) and -factor (red), together with the corresponding simulation results (dashed lines) corrected for experimental resolution and scattering losses