Metamaterial-based octave-wide terahertz bandpass filters

We present octave-wide bandpass filters in the terahertz (THz) region based on bilayer-metamaterial (BLMM) structures. The passband region has a super-Gaussian shape with a maximum transmittance approaching 70% and a typical stopband rejection of 20 dB. The design is based on a metasurface consistin...

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Veröffentlicht in:Photonics research (Washington, DC) DC), 2023-04, Vol.11 (4), p.526
Hauptverfasser: Maleki, Ali, Singh, Avinash, Jaber, Ahmed, Cui, Wei, Xin, Yongbao, Sullivan, Brian T., Boyd, Robert W., Ménard, Jean-Michel
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Sprache:eng
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Zusammenfassung:We present octave-wide bandpass filters in the terahertz (THz) region based on bilayer-metamaterial (BLMM) structures. The passband region has a super-Gaussian shape with a maximum transmittance approaching 70% and a typical stopband rejection of 20 dB. The design is based on a metasurface consisting of a metallic square-hole array deposited on a transparent polymer, which is stacked on top of an identical metasurface with a subwavelength separation. The superimposed metasurface structures were designed using finite-difference time-domain (FDTD) simulations and fabricated using a photolithography process. Experimental characterization of these structures between 0.3 and 5.8 THz is performed with a time-domain THz spectroscopy system. Good agreement between experiment and simulation results is observed. We also demonstrated that two superimposed BLMM (2BLMM) devices increase the steepness of the roll-offs to more than 85 dB/octave and enable a superior stopband rejection approaching 40 dB while the maximum transmittance remains above 65%. This work paves the way toward new THz applications, including the detection of THz pulses centered at specific frequencies, and an enhanced time-resolved detection sensitivity toward molecular vibrations that are noise dominated by a strong, off-resonant, driving field.
ISSN:2327-9125
2327-9125
DOI:10.1364/PRJ.472109