Abstract
Novel spoof surface plasmon based terahertz (THz) antennas are realized using a few number of rectangular grooves perforated in ultrathin metal stripes and the properties of them, including both scattering cross sections and field enhancement, are numerically analyzed. The dependence of these properties on the incident angle and groove number is discussed and the results show that sharp resonances in scattering cross section spectra associated with strong local field enhancement can be achieved. These resonances are due to the formation of Fabry-Perot resonances of the spoof surface plasmon mode and it is found that the order of resonance exhibiting strongest field enhancements is found to coincide with the number of grooves at normal incidence, due to hybridization of the antenna resonance with the individual groove resonance. The terahertz hotspots within the grooves at resonances due to the local field enhancement may open up new possibilities for the investigation of terahertz-matter interactions and boost a variety of THz applications including novel sensing and THz detections. The planar stripe antennas with sharper resonances than dipolar-like resonances, together with their ease of fabrication may also promise new design methodology for metamaterials.
Highlights
Novel spoof surface plasmon based terahertz (THz) antennas are realized using a few number of rectangular grooves perforated in ultrathin metal stripes and the properties of them, including both scattering cross sections and field enhancement, are numerically analyzed
Many chemicals and molecules have their vibrational and rotational resonance frequencies located in the THz regime, resulting in unique absorption spectral features, which can be used for fingerprint detection of specific chemicals
Due to the low efficiency of the optical-THz conversion in photoconductive antennas or the low efficiency in the nonlinear optical processes involved in the optical generation of THz pulses, the resulted THz signal is usually not strong enough in terms of spectral power density over a large bandwidth and the spectral information obtained with THz time-domain spectroscopy (THz-TDS) can be blurred by the environmental turbulence
Summary
Novel spoof surface plasmon based terahertz (THz) antennas are realized using a few number of rectangular grooves perforated in ultrathin metal stripes and the properties of them, including both scattering cross sections and field enhancement, are numerically analyzed. One of the effective and practical ways of realizing local field enhancement is to use metallic structures whose dielectric functions are negative to support the excitation of surface plasmon (SP) modes[6].
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