Comparison of infrared frequency selective surfaces fabricated by direct-write electron-beam and bilayer nanoimprint lithographies

We report on the fabrication of crossed-dipole resonant filters by direct-write electron-beam and nanoimprint lithographies. Such structures have been used as spectrally selective components at visible, microwave, and infrared wavelengths. Imprinting is accomplished in a modified commercial hot press at 155°C. The replica is then etched in oxygen plasma and developed in chlorobenzene to selectively dissolve the poly͑methylmethacrylate and methacrylic acid͒ and poly͑methylmethacrylate͒ bilayer resist. This step enhances undercut and improves lift-off metalization. Infrared fourier transform spectroscopy was performed to characterize the transmission response of the frequency selective surfaces ͑FSSs͒ fabricated. The resonant behavior for the direct-write FSS was found to be 5.3 m and for the nanoimprinted FSS to be 6 m. The shift towards longer wavelengths is consistent with the dimensions obtained for the FSSs elements in both cases

Comparison of infrared frequency selective surfaces fabricated by direct-write electron-beam and bilayer nanoimprint lithographies

We report on the fabrication of crossed-dipole resonant filters by direct-write electron-beam and nanoimprint lithographies. Such structures have bean used as spectrally selective components at visible, microwave; and infrared wavelengths. Imprinting is accomplished in a modified commercial hot press at 155 degreesC. The replica is then etched in oxygen plasma and developed in chlorobenzene to selectively dissolve the poly(methylmethacrylate and methacrylic acid) and poly(methylmethacrylate) bilayer resist. This step enhances undercut and improves lift-off metalization. Infrared fourier transform spectroscopy was performed to characterize the transmission response of the frequency selective surfaces (FSSs) fabricated. The resonant behavior for the direct-write FSS was found to be 5.3 mum and for the nanoimprinted FSS to be 6 mum. The shift towards longer wavelengths is consistent with the dimensions obtained for the FSSs elements in both cases. (C) 2000 American Vacuum Society. [S0734-211X(00)09706-4]

Resonant Enhancement Of Emission And Absorption Using Frequency Selective Surfaces In The Infrared

We investigate the infrared properties of frequency selective surfaces consisting of aluminum patches on silicon substrates. Resonant behavior is found not only in the transmission and reflection, but also in the absorption and emission of these surfaces. The resonance location is a controllable function of the surface pattern. Simple model calculations reproduce well the qualitative behavior of our samples. © 2002 Elsevier Science B.V. All rights reserved

Refractive-Index And Element-Spacing Effects On The Spectral Behavior Of Infrared Frequency-Selective Surfaces

Transmission and reflection characteristics of inductive-mesh frequency-selective surfaces were measured in the 4-12-µm range. Specific issues investigated include the effect of interelement spacing on the location and width of the resonance and the influence of superstrate and substrate refractive indices on the spectral response of the structure. © 2000 Optical Society of America

Modeling Parameters For The Spectral Behavior Of Infrared Frequency-Selective Surfaces

Comparisons of experiment and theory are presented for transmission spectra over the range 2–15 μm of a set of frequency-selective surfaces consisting of arrays of simple dipole patches of aluminum on or in silicon. The arrays are fabricated by direct-write electron-beam lithography. Important parameters controlling the spectral shape are identified, such as dipole length, spacing, resistance, and dielectric surroundings. The separate influence of these variables is exhibited. Encouraging agreement between simple model calculations and the measurements is found. © 2001 Optical Society of America

Improving solar cell efficiency using photonic band-gap materials

The potential of using photonic crystal structures for realizing highly efficient and reliable solar-cell devices is presented. We show that due their ability to modify the spectral and angular characteristics of thermal radiation, photonic crystals emerge as one of the leading candidates for frequency- and angular-selective radiating elements in thermophotovoltaic devices. We show that employing photonic crystal-based angle- and frequency-selective absorbers facilitates a strong enhancement of the conversion efficiency of solar cell devices without using concentrators. © 2007 Elsevier B.V. All rights reserved