Phys.org March 17, 2022
In photonic circuits optical isolators are used to prevent light from reentering the system and destabilizing it. But guiding light in one direction often requires large magnets, making these circuits difficult to create on a small scale. By coupling light confined in a nanophotonic waveguide with an atomically thin, two-dimensional semiconductor, a team of researchers in the US (University of Chicago, Argonne National Laboratory) exploited the properties of both the light and the material to guide photons in one direction. They fabricated titanium dioxide waveguides directly on the surface of low-disorder, boron nitride-encapsulated tungsten diselenide (WSe2). Photoluminescence from excitonic states into the waveguide could be electrically switched between balanced and directionally biased emission. The nanophotonic waveguide can function as a near-field source for diffusive exciton fluxes, which display valley and spin polarizations that are inherited from the interface chirality. Such photonic devices could be integrated into future optical computers…read more. TECHNICAL ARTICLE
Chiral nanophotonic–TMDC interface. Credit: Nature Photonics (2022)Â