Enhanced infrared transmission through subwavelength hole arrays in a thin gold film mounted with dielectric micro-domes

Abstract

Dielectric micro-domes were mounted on the subwavelength holes of a periodically perforated gold film such that a lens-like micro-dome covers each hole. In comparison to the extraordinary transmission through an array of bare holes in the gold film, this structure showed a further enhanced transmission over a larger range of incident angles with much larger bandwidth at mid-wave infrared wavelengths (m). The structure was fabricated using laser interference lithography, a novel back-exposure with an ultra-violet laser, and lift-off process that left behind the micro-domes of SU-8, covering each of the holes in the gold film. The measured transmittance of these perforated gold films, with and without the micro-domes, was verified by electromagnetic wave simulations. The enhanced transmittance arises from the scattered electromagnetic fields of the micro-domes, which couple the incident light efficiently via the scattered near-fields into the waveguide modes of holes in the plasmonic film. The increased transmittance and the highly enhanced and localized near-fields can be used to enhance the photo-response of infrared detectors over relevant bands, for example, the m band that is used for thermal imaging applications.

Simple trilayer metamaterial absorber associated with Fano-like resonance

“…In case of TE polarization, magnitude of electric remains constant so there is only slight variation in the magnitude of deeps and peaks in the reflectance spectra at different incident angles. In case of TM polarization, magnitude of electric field changes due to which coupling condition for spoof SPPs changes, and hence there is finite variation in the magnitude of deeps and peaks as well as spectral shift in the resonance [55].…”

Interdisk spacing effect on resonant properties of Ge disk lattices on Si substrates

“…Recently, intensive research has been carried out on coatings of metal and/or dielectric particles as an alternative to continuous antireflection films 5 – 9 . Their action is based on the excitation of plasmonic 10 , 11 or electromagnetic (EM) resonances 12 – 15 in metal and dielectric particles, respectively. Compared to continuous films, the capabilities of antireflection coatings made of particles are wider.…”

Broadband Antireflection Coatings Made of Resonant Submicron- and Micron-Sized SiGe Particles Grown on Si Substrates

“…This effect can be enhanced by means of the Rayleigh anomaly introducing a diffraction effect occurring owing to the EM radiation scattering on the hole edges [6]- [8]. It was shown that the placement of dielectric particles into metal film holes can give an additional positive effect based on the excitation of magnetic and electrical resonances in dielectric particles [2], [4], [9]- [11]. Although the use of such hybrid metal-dielectric antireflection coatings provides a significant increase in the efficiency of optoelectronic converters in the mid-IR region, they have the disadvantage of containing metal components that cause the dissipation of EM radiation.…”