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arXiv · 2505.03905

Directional Thermal Emission Across Both Polarizations in Planar Photonic Architectures

David E. Abraham·Daniel Cui·Baolai Liang·Jae S. Hwang·Parthiban Santhanam·Linus Kim·Rayen Lin·Aaswath P. Raman
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Abstract

Directional and spectral control of thermal emission is essential for applications in energy conversion, imaging, and sensing. Existing planar, lithography-free epsilon-near-zero (ENZ) films only support transverse-magnetic (TM) control of thermal emission via the Berreman mode and cannot address transverse-electric (TE) waves due to the absence of natural optical magnetism over optical and infrared wavelengths Here, we introduce a hyperbolic metamaterial comprising alternating layers of degenerately-doped and intrinsic InAs that exhibits an epsilon-and-mu-near-zero (EMNZ) response, enabling dual-polarized, directionally and spectrally selective thermal emission. We first theoretically demonstrate that a mu-near-zero (MNZ) film on a perfect magnetic conductor supports a magnetic Berreman mode, absorbing TE-polarized radiation in analogy to the conventional Berreman mode supported in TM polarization. Using genetic and gradient-descent optimization, we design a dual-polarized emitter with independently tunable spectral peaks and emission angles. Parameter retrieval via homogenization confirms simultaneous EMNZ points at the target wavelengths and angles. Finally, experimental measurement of a sample fabricated via molecular beam epitaxy exhibits high absorptivity peaks for both polarizations in close agreement with simulations. This work realizes lithography-free, dual-polarized, spectrally and directionally selective emitters, offering a versatile platform for advanced infrared thermal management and device integration.

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David E. Abraham, Daniel Cui, Baolai Liang, Jae S. Hwang, Parthiban Santhanam, Linus Kim, Rayen Lin, Aaswath P. Raman. 2025-05-06. Directional Thermal Emission Across Both Polarizations in Planar Photonic Architectures. https://arxiv.org/abs/2505.03905

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