# Photonic thermal diode enabled by surface polariton coupling in nanostructures

## TL;DR

This paper proposes a near-field photonic thermal diode using surface polariton coupling in nanostructures, achieving high rectification efficiency by tuning resonant modes in silicon carbide components.

## Contribution

It introduces a novel diode design based on surface phonon-polariton coupling in nanostructures with high rectification efficiency in the infrared.

## Key findings

- Achieves 80-87% rectification efficiency over 700-1000 K temperature range.
- High efficiency depends on vacuum gap, substrate dielectric, and film thickness.
- Potential for further enhancement with complex nanostructures.

## Abstract

A novel photonic thermal diode concept operating in the near field and capitalizing on the temperature-dependence of coupled surface polariton modes in nanostructures is proposed. The diode concept utilizes terminals made of the same material supporting surface polariton modes in the infrared, but with dissimilar structures. The specific diode design analyzed in this Letter involves a thin film and a bulk, both made of 3C silicon carbide, separated by a subwavelength vacuum gap. High rectification efficiency is obtained by tuning the antisymmetric resonant modes of the thin film, resulting from surface phonon-polariton coupling, on- and off-resonance with the resonant mode of the bulk as a function of the temperature bias direction. Rectification efficiency is investigated by varying structural parameters, namely the vacuum gap size, the dielectric function of the substrate onto which the film is coated, and the film thickness to gap size ratio. Calculations based on fluctuational electrodynamics reveal that high rectification efficiencies in the 80% to 87% range can be maintained in a wide temperature band (~ 700 K to 1000 K). The rectification efficiency of the proposed diode concept can be potentially further enhanced by investigating more complex nanostructures such as gratings and multilayered media.

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Source: https://tomesphere.com/paper/1703.09862