Coherent Thermal Emission from Large-Scale Suspended Nanomechanical Membranes

TL;DR

This paper demonstrates a novel method for generating coherent thermal infrared light using large-scale suspended nanomechanical membranes of SiC, avoiding complex lithography and polaritonic excitations, enabling scalable and polarization-insensitive coherent emission.

Contribution

It introduces a simple wave interference approach with unpatterned membranes to produce coherent thermal emission, bypassing previous limitations of polaritonic methods.

Findings

Achieved polarization-insensitive, narrowband coherent emission.

Demonstrated large-scale, lithography-free membranes for thermal light.

Showed antenna-like directivity in thermal emission.

Abstract

Thermal radiation is an abundant form of incoherent light. Generating coherent infrared light through incandescence promises a cheap alternative to the costly and epitaxially complex quantum cascade laser, however it remains a fundamental challenge. Previous approaches leveraged the spatial coherence of polaritonic excitations that occur in the thermal near-field, by diffracting them into the far-field zone via patterned micro- or nano-scatterers. This approach requires high-resolution lithography, is difficult to scale-up, and yields limited outcoupled radiation due to the intrinsically polarized nature of polaritons. We overcome these limitations and report coherent thermal emission through simple wave interference. We show that unpatterned, millimeter-scale, suspended nanomechanical membranes of SiC operate for both linear polarizations and exhibit antenna-like directionality without relying on the excitation of near-field polaritons. The ability to generate polarization-insensitive, narrowband and spatially coherent incandescent light without lithography at large scales paves the way towards democratizing thermal infrared technologies.