Enhancement of high-harmonic generation from 2D materials by distributed Bragg reflector

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have the advantages of strong optical nonlinear response, negligible harmonic absorption, and easy fulfillment of the phase-matching condition and are considered as attractive materials for high-harmonic generation (HHG). However, the high-harmonic yield is limited by the short light–matter interaction length. Here, we demonstrate the enhancement of HHG in 2D TMDs by a semi-open structure that couples the 2D TMDs with a distributed Bragg reflector (DBR). By using this scheme, the electric field of the driving laser pulse can be enhanced in the full area of the light–TMD interaction. The semi-open-cavity structure avoids the absorption of harmonics by the cavity. Experimental results show that the HHG of TMDs on the DBR structure is enhanced by more than two orders of magnitude compared with that of TMDs on the normal substrate. Our work paves the way for optimizing nanoscale solid-state HHG light sources.