Abstract
We have observed resonant terahertz transmission peaks in samples comprising perforated periodic hole array in a metal film, covered with a high dielectric substrate. These resonant transmissions arise from the interplay between waveguide modes in dielectric substrate and the periodic hole array in the metal film. Finite difference time domain (FDTD) simulations show good agreement with the data, in support of the proposed mechanism. Inducing additional resonant transmissions using guided modes can lead to the ease in tuning the transmission peak frequencies that are potentially useful to terahertz (THz) bio-sensing.
Highlights
Extraordinary transmission (ET) through a periodically perforated metal plate may be attributed to the electromagnetic (EM) grating resonances that can occur at frequencies where the structure dimensions properly match the relevant wavelength [1]
We explore the relationship between the dispersion relations of the waveguide modes in the dielectric layer and show how they can couple to the perforated hole array in the metal film
The silicon layer supports guided modes with low loss propagation parallel to the metal surface. These tangential propagating waveguide modes are built up by the scattering of the metal hole array, and these guided modes can interact with the hole array that serves as one bounding surface of the waveguide, leading to extraordinary transmissions
Summary
Extraordinary transmission (ET) through a periodically perforated metal plate may be attributed to the electromagnetic (EM) grating resonances that can occur at frequencies where the structure dimensions properly match the relevant wavelength [1]. One of the most important characteristics of ET is the significant increase in the near-field intensity of the transmitted radiation, making them useful for the detection of small amounts of sample [10] For such applications tuning the resonant frequencies can be very important, and it would be desirable to have additional transmission frequencies in the THz regime in addition to the usual cases. The field patterns for the peaks of 1-6, corresponding to the (1, 0) diffraction mode, are exactly the same except the differences in their magnitudes This is shown in the upper panel of Fig. 2(b). The field pattern of peak 7, which corresponds to the (1, 1) diffraction mode, is shown in the lower panel of Fig. 2 (b)
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