We theoretically demonstrate a novel, efficient and cost effective thermal emitter using a Mie-resonance metamaterial for thermophotovoltaic (TPV) applications. We propose for the first time the design of a thermal emitter which is based on nanoparticle-embedded thin film. The emitter consists of a thin film of SiO₂ on the top of tungsten layer deposited on a substrate. The thin film is embedded with tungsten nanoparticles which alter the refractive index of the film. This gives rise to desired emissive properties in the wavelength range of 0.4 μm to 2 μm suitable for GaSb and InGaAs based photovoltaics. Effective dielectric properties are calculated using Maxwell-Garnett-Mie theory. Our calculations indicate this would significantly improve the efficiency of TPV cells. We introduce a new parameter to gauge the efficacy of thermal emitters and use it to compare different designs.

Computational and experimental investigations of angle-dependent light transmission through nanometric cross-shaped aperture arrays in thin metal films are presented. It is shown that high-transmission associated with the excitation of localized surface plasmons within the apertures can be tailored to exhibit polarization- and angle-independent performance.

Microscopic thin films have shown wavelength selectivity in the context of radiative heat transfer. We propose a methodology to shift the wavelength selectivity in the desired location. This work deals with the far-field and near-field radiation from thin films embedded with nanoparticles. The calculations of emission spectra are performed using the Fresnel equations in the far-field limit, and using the dyadic Green's function formalism for transmissivity between the closely spaced objects in the near-field regime. For the media doped with nanoparticles, an effective dielectric function using the Maxwell-Garnett-Mie theory is used to calculate emissivity and radiative heat transfer. It has been shown that the wavelength selectivity in the emission spectra can be influenced by varying the size and/or the volume fraction of nanoparticles. We characterize the wavelength selectivity using real and imaginary parts of the effective refractive index. We show that the influence of nanoparticles on wavelength selectivity is different depending on whether the particles are of polar materials or are metallic.

Here localized surface plasmon (LSP) resonances occurring inside cross-shaped apertures arranged in thin metallic films are investigated. It is shown that these resonances can be controlled by altering the geometry of the apertures, whereas surface plasmon polariton excitation and Wood anomalies arising as a consequence of the periodicity distorts the spectrum produced by isolated LSP resonances. Simulations showing the behavior of single apertures versus periodic arrays of apertures are compared with experimental results for periodic arrays.

We show experimental results for the optical transmission of planar metallic films closely coupled to periodic sub-wavelength structures; exceptionally-high transmission levels (up to 39%) are measured for these otherwise-opaque films. The measured dispersion of the transmission maxima agrees well with the theoretical dispersion of surface plasmon polariton (SPP) modes on a planar metal film, which strongly suggests that the excitation of these SPP modes is responsible for the exceptional transmission features. This is further supported by rigorous coupled wave analysis (RCWA) simulations. The overall transmission is a result of the coupling between the incident light and the SPP modes, as well as the localized surface plasmon (LSP) modes within the structure.