We investigate the characteristics of electromagnetic wave reflection and transmission by multilayered structures consisting of a pair of left-handed material (LHM) and dielectric slabs inserted between two semi-infinite dielectric media. The theoretical aspect is based on Maxwell's equations and matching the boundary conditions for the electric and magnetic fields of the incident waves at each layer interface. We calculate the reflected and transmitted powers of the multilayered structure taking into account the widths of the slabs and the frequency dependence of permittivity and permeability of the LHM. The obtained results satisfy the law of conservation of energy. We show that if the semi-infinite dielectric media have the same refractive index and the slabs have the same width, then the reflected (and transmitted) powers can be minimized (and maximized) and the powers-frequency curves show no ripple. On the other hand if the semi-infinite dielectric media have different values of refractive indices and the slabs have different widths, then under certain conditions the situation of minimum and maximum values of the mentioned powers will be reversed.

In this paper, a one-dimensional periodic multilayer is optimized for potential application as thermophotovoltaic (TPV) emitter. The proposed structure was prepared through a magnetron sputtering process. The influence of layers geometric parameters of the proposed structure on the spectral emittance is studied by using the rigorous coupled-wave analysis (RCWA)

In this paper, a one-dimensional multilayer is optimized for potential applications as thermophotovoltaic (TPV) selective emitter. The proposed TPV emitter was fabricated through a magnetron sputtering process by using the radio frequency (RF) magnetron sputtering system. The spectral emittance of the proposed TPV emitter is measured by using spectral transmittance and reflectance measurement system at wavelength from 0.3 μm to 2.5 μm at near-normal incident 8˚. The bidirectional reflectance distribution function BRDF is measured by three axis automated scatterometer (TAAS). The effect of the diffraction orders and plane of incidence on the spectral emittance of the proposed TPV emitter is calculated numerically by using the rigorous coupled-wave analysis (RCWA). The emittance spectrum of the proposed TPV selective emitter shows three close to unity emission peaks which are explained by the surface plasmon polariton (SPP), gap plasmon polariton (GPP) and magnetic polariton (MP) excitation. The results show that the proposed emitter has high emittance value in the spectral range of 0.69 < λ <1.97 μm and low reflectance distribution BRDF•cosθ value. It also has multi-reflection points and it works as a mirror. The measured results are in good agreement with the simulation results. The results show that the proposed TPV emitter, if used as a selective emitter with a low band gap photovoltaic cell (GaSb), would lead to high TPV overall efficiency and high electrical output power.

In this study, a one-dimensional microstructure tungsten grating is optimized for potential application as Thermo Photovoltaic (TPV) emitter. The influence of gratings geometric parameters on the spectral emittance are studied by using the Rigorous Coupled-Wave Analysis (RCWA). The results show that the spectral emittance is affected by the gratings geometrical parameters and insensitive to the direction. The optimum parameters of the proposed structure are grating period 1.4 µm, a filling ratio 0.8 and grating height 0.2 µm. A broad peak of high emittance is obtained at wavelengths between 0.5 and 1.8 µm. A peak emittance close to unity at wavelengths between 0.5 and 2 µm is achieved and it drops below 0.2 at wavelengths above 2 µm. This can be explained by the surface plasmon polaritons excitation coupled with the grating microstructures. At longer wavelengths, the emittance remains low and this is highly desired for thermo photovoltaic applications to reduce the thermal leakage due to low-energy photons that do not produce any photocurrent. The proposed structure can be used as a selective emitter for TPV applications.

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