2024/12/23 by Jae Sung Hwang, Jae S. Hwang, Hwang, Jae S. +4 · 1 voice
Engineering · Physics and Astronomy · #Applied Physics (physics.app-ph) #Calibration and Measurement Techniques #FOS: Physical sciences #Optical and Acousto-Optic Technologies #Optics (physics.optics) #Thermography and Photoacoustic Techniques #physics.app-ph #physics.optics
paper · pdf · doi:10.48550/arxiv.2412.17659
openalex publication_date 2024/12/23 · arxiv published 2024/12/23 · arxiv updated 2024/12/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Tuning the spatial extent of directional thermal emission across an arbitrary, and fixed spectral bandwidth is a fundamentally enabling capability for a range of emerging applications such as thermophotovoltaics, thermal imaging, and radiative cooling. However, previous experimental demonstrations were limited to narrow bandwidths, and the resonance frequency itself changed significantly as a function of the reconfigured directional response. Here, we demonstrate thermo-optic tuning of directional infrared emissivity using InAs-based gradient ENZ materials functioning as broadband directional thermal emitters whose angular selectivity can be modified via thermal free-carrier effects. We experimentally demonstrate two emitters achieving a 5° and 10° increase in the angular extent of their directional emissivity in the p-polarization across a prescribed, broad wavelength range of operation (12.5 to 15μm), for moderate temperatures below 400 K. Temperature-driven control of directional emissivity offers a new mode of post-fabrication control of radiative heat transfer that may in turn enable novel device functionalities.