Phys.org  February 15, 2024 A team of researchers in the US (US Naval Research Laboratory, Kansas State University) demonstrated how hexagonal boron nitride (hBN) slabs tuned to the correct thickness act as optical waveguides, enabling direct optical coupling of light emission from encapsulated layers into waveguide modes. They integrated molybdenum selenide (MoSe2) and tungsten selenide (WSe2) within hBN-based waveguides and demonstrated direct coupling of photoluminescence emitted by in-plane and out-of-plane transition dipoles (bright and dark excitons) to slab waveguide modes. They demonstrated that dry etched hBN edges are an effective out-coupler of waveguided light without the need for oil-immersion optics. […]