Abstract
We demonstrated tailored plasmon-induced transparency (PIT) in a metal (Au)–insulator (SiO2)–metal (Ag) (MIM) structure, where the Fano interference between the MIM waveguide mode and the surface plasmon polariton (SPP) resonance mode induced a transparency window in an otherwise opaque wavenumber (k) region. A series of structures with different thicknesses of the Ag layer were prepared and the attenuated total reflection (ATR) response was examined. The height and width of the transparency window, as well as the relevant k-domain dispersion, were controlled by adjusting the Ag layer thickness. To confirm the dependency of PIT on Ag layer thickness, we performed numerical calculations to determine the electric field amplitude inside the layers. The steep k-domain dispersion in the transparency window is capable of creating a lateral beam shift known as the Goos–Hänchen shift, for optical device and sensor applications. We also discuss the Fano interference profiles in a ω − k two-dimensional domain on the basis of Akaike information criteria.
Highlights
The SiO2 layer sustained the MIM waveguide (MIMWG). The thickness of this layer was designed so that the lowest transverse magnetic (TM) mode in the MIMWG appeared at the same incident angle as the surface plasmon polariton (SPP) resonance at the Ag–air interface at the incident wavelength of 632.8 nm
We demonstrated that the height and width of the transparency window of plasmon-induced transparency (PIT) in the metal– insulator–metal (MIM) structure can be tailored through adjustment of the Ag layer thickness
The present system could preserve the sensitivity of SPP sensors, because the final layer sustains SPP and the evanescent field emerges from the final layer
Summary
MIM samples were fabricated on quartz substrates (25 mm × 25 mm × 1 mm) using an electron cyclotron resonance sputtering method. The substrates were attached on a right-angle quartz prism (25 mm × 25 mm × 25 mm) using an index mating oil. For the measurement of the k profiles in the ATR response [Fig. 2(a)], a He-Ne laser was used as the incident light source. For the mapping of Fano interference in the ω − k two-dimensional domain [Fig. 5(b)], we used a halogen lamp as the incident light source. The collimated light beam from the lamp was passed through a monochromator, polarizer, and 1/2 wavelength plate. The angular ATR response was measured using the collimated beam in 10-nm step increments; from this, a ω − k two-dimensional space mapping was constructed
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