Abstract
A planar terahertz metamaterial sensor consisting of a corrugated metal stripe perforated by three rectangular grooves is proposed and investigated numerically. Due to the formation of Fabry-Perot resonance of the spoof surface plasmons mode on the corrugated metal stripe, the extremely sharp resonance in transmission spectrum associated with strong local field enhancement and high quality factor can be realized and exploited for ultrasensitive sensing. Since the intense interaction between electromagnetic waves and analyte materials, the frequency sensitivity of 1.966 THz per refractive index unit and the figure of merit of 19.86 can be achieved. Meanwhile, the film thickness sensitivity of this metamaterial sensor is higher than 52.5 GHz/μm when the analyte thickness is thinner than 4 μm. More interestingly, we find that the metal thickness has a great effect on the sensor performance. These findings open up opportunities for planar metamaterial structures to be developed into practical sensors in terahertz regime.
Highlights
Metamaterials (MMs) are periodic arrangement of artificially structured materials, in which the dimension of the unit cell is much smaller than the incident wavelength, have attracted much attention in the past decades[1, 2]
More THz electric fields are confined within the grooves at this sharp resonance frequency than that of the broad one, indicating the stronger interaction between THz waves and the analyte at the sharp frequency
We have theoretically demonstrated an ultrasensitive metamaterials sensor, in which the unit cell is composed of a corrugated metallic stripe perforated by three rectangle grooves
Summary
Metamaterials (MMs) are periodic arrangement of artificially structured materials, in which the dimension of the unit cell is much smaller than the incident wavelength, have attracted much attention in the past decades[1, 2]. With the strongly confined electromagnetic field and sharp spectral resonance features, MMs structures can strengthen field-matter interaction and improve Q factor, which is similar to surface plasmon polaritons (SPPs) sensing at visible wavelengths[19, 20]. For the first time to the best of our knowledge, we propose an ultrasensitive THz planar MMs sensor based on the excitation of the sharp SSPs resonance mode. The wave vector of the SSP modes deviates from the black straight line with the frequency increasing, and the dispersion curves becomes flat when the frequency asymptotes to a certain value. The dispersion curve moves to the right when the groove height increases, showing the tighter modal confinement tendency
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