Fluctuational electrodynamics for nonlinear materials in and out of thermal equilibrium

Abstract

We develop fluctuational electrodynamics for media with nonlinear optical response in and out of thermal equilibrium. Starting from the stochastic nonlinear Helmholtz equation and using the fluctuation dissipation theorem, we obtain perturbatively a deterministic nonlinear Helmholtz equation for the average field, the physical linear response, as well as the fluctuations and Rytov currents. We show that the effects of nonlinear optics, in or out of thermal equilibrium, can be taken into account with an effective, system-aware dielectric function. We discuss the heat radiation of a planar, nonlinear surface, showing that Kirchhoff's must be applied carefully. We find that the spectral emissivity of a nonlinear nanosphere can in principle be negative, implying the possibility of heat flow reversal for specific frequencies.

References in corpus (6)

• Measurement of the Temperature Dependence of the Casimir-Polder Force
• Fluctuating surface-current formulation of radiative heat transfer for arbitrary geometries
• Many body heat radiation and heat transfer in the presence of a non-absorbing background medium
• Electromagnetic Green's function for layered systems: Applications to nanohole interactions in thin metal films
• Radiative heat transfer in nonlinear Kerr media
• Anharmonic particles: suppressing van der Waals forces by an external field

Cited by in corpus (2)

• Quantum nonlinear mixing of thermal photons to surpass the blackbody limit
• Maxwell Eigenmode approach to the Casimir-Lifshitz Torque