Transient Measurement of Near-field Thermal Radiation between Macroscopic Objects

TL;DR

This paper introduces a rapid, all-optical transient measurement method for near-field thermal radiation between macroscopic objects, achieving high accuracy and broad material applicability, with potential for fundamental and practical insights.

Contribution

The paper presents a novel transient all-optical approach for measuring near-field radiative heat transfer with high speed and accuracy, applicable to various materials and configurations.

Findings

Significant super-Planckian radiation observed due to near-field coupling.

Measurement accuracy within 2.7% discrepancy across temperature range.

Method effective for different object sizes and material systems.

Abstract

The involvement of evanescent waves in the near-field regime could greatly enhance the spontaneous thermal radiation, offering a unique opportunity to study nanoscale photon-phonon interaction. However, accurately characterizing this subtle phenomenon is very challenging. This paper proposes a transient all-optical method for rapidly characterizing near-field radiative heat transfer (NFRHT) between macroscopic objects, using the first law of thermodynamics. Significantly, a full measurement at a fixed gap distance is completed within tens of seconds. By simplifying the configuration, the transient all-optical method achieves high measurement accuracy and reliable reproducibility. The proposed method can effectively analyze the NFRHT in various material systems, including SiO2, SiC, and Si, which involve different phonon or plasmon polaritons. Experimental observations demonstrate significant super-Planckian radiation, which arises from the near-field coupling of bounded surface modes. Furthermore, the method achieves excellent agreement with theory, with a minimal discrepancy of less than 2.7% across a wide temperature range. This wireless method could accurately characterize the NFRHT for objects with different sizes or optical properties, enabling the exploration of both fundamental interests and practical applications.