Emission bandwidth control on a two-dimensional superlattice microcavity array.

Narrowband thermal emission at high temperatures is required for various thermal energy systems. However, the large lossy energy of refractory metals induces a broad bandwidth emission. Here, we demonstrated a two-dimensional (2D) superlattice microcavity array on refractory metals to control the emission bandwidth.

Multiband infrared emissions limited in the grazing angle from metal-dielectric-metal metamaterials.

Thermal radiation management remains a challenge because of the incoherent and isotropic nature of electromagnetic waves. In this study, a multiband and angular-selective infrared emitter, consisting of a simple one-dimensional (1D) metal-dielectric-metal metamaterial, is demonstrated. Although this structure has been well known as spectrally selective emitters, we analytically reveal that when the dielectric layer thickness is much smaller than the wavelength of interest (< 1/10), directive emission at nearly equal to the grazing angles (> 80°) can be obtained at multiple resonant wavelengths.

Effective photon recycling in solar thermophotovoltaics using a confined cuboid emitter.

For effective photon conversion in solar-thermophotovoltaic (TPV) systems, an enclosed-space confined emitter system is proposed, and its power generation potential is demonstrated. A cuboid monolithic absorber/emitter is applied for higher extraction efficiency without dead areas. An analysis using an enclosed space shows a 4.

Quantitative evaluation of optical properties for defective 2D metamaterials based on diffraction imaging.

Metamaterials are intriguing candidates for energy conversion systems, and contribute to the control of thermal radiation spectra. Large-scale devices are required to provide high energy flux transfer. However, the surface microstructure of large-scale metamaterials suffers from fabrication defects, inducing optical property degradation.

High-current density and high-asymmetry MIIM diode based on oxygen-non-stoichiometry controlled homointerface structure for optical rectenna.

Optical rectennas are expected to be applied as power sources for energy harvesting because they can convert a wide range of electromagnetic waves, from visible light to infrared. The critical element in these systems is a diode, which can respond to the changes in electrical polarity in the optical frequency. By considering trade-off relationship between current density and asymmetry of IV characteristic, we reveal the efficiency limitations of MIM diodes for the optical rectenna and suggest a novel tunnel diode using a double insulator with an oxygen-non-stoichiometry controlled homointerface structure (MO/MO).