T Operator Bounds on Angle-Integrated Absorption and Thermal Radiation for Arbitrary Objects

Sean Molesky; Weiliang Jin; Prashanth S Venkataram; Alejandro W Rodriguez

doi:10.1103/PhysRevLett.123.257401

T Operator Bounds on Angle-Integrated Absorption and Thermal Radiation for Arbitrary Objects

Phys Rev Lett. 2019 Dec 20;123(25):257401. doi: 10.1103/PhysRevLett.123.257401.

Authors

Sean Molesky¹, Weiliang Jin², Prashanth S Venkataram¹, Alejandro W Rodriguez¹

Affiliations

¹ Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
² Department of Electrical Engineering, Standford University, Stanford, California 94305, USA.

PMID: 31922767
DOI: 10.1103/PhysRevLett.123.257401

Abstract

We derive fundamental per-channel bounds on angle-integrated absorption and thermal radiation for arbitrarily structured bodies-for any given material susceptibility and bounding region-that simultaneously encode both the per-volume limit on polarization set by passivity and geometric constraints on radiative efficiencies set by finite object sizes through the scattering T operator. We then analyze these bounds in two practical settings, comparing against prior limits as well as near optimal structures discovered through topology optimization. Principally, we show that the bounds properly capture the physically observed transition from the volume scaling of absorptivity seen in deeply subwavelength objects (nanoparticle radius or thin film thickness) to the area scaling of absorptivity seen in ray optics (blackbody limits).