Abstract
In this study we report the first on the terahertz (THz) transmission characteristics of a guided-mode resonance (GMR) filter made of all-dielectric material. Two strong transverse electric (TE) resonance modes, TE0,1 and TE1,1, and one strong transverse magnetic (TM) resonance mode, TM0,1, were detected. The measured resonances can be explained by diffraction from the grating surface of the GMR filter, and by guiding along the inside of the filter (slab waveguide). Because two identical GMR filters were employed to overcome limited grating numbers, the measured Q-factors of the TM0,1, TE1,1, and TM0,1 modes were as high as 62.9, 71.0, and 74.4 respectively. Also, we obtained polarization efficiencies of up to 96.9, 96.3, and 92.9% for the TM0,1, TM1,1, and TM0,1 modes, respectively, when the GMR filter was rotated to 90°. By increasing the incident THz beam angle, one TE resonance can be divided into two TE resonances, and the resonant frequency can be adjusted like a THz tunable resonance filter. Furthermore, when the GMR filters were inserted between Teflon plates, only the TM1,1 mode was perfectly removed. The designed GMR filter has a high Q-factor, tunable filter, good polarizer, and good modulator characteristics. These experimental results were in good agreement with simulation results.
Highlights
The thin metallic or dielectric patterns on a frequency-selective surface (FSS) can reflect and transmit specific electromagnetic fields
The proposed guided-mode resonance (GMR) filter can reduce reflection and attenuation losses because it is made of an all-dielectric material, such as quartz
It can be made from other dielectric materials without metal patterns on the surface, including Teflon, silica, Polyethylene, etc., which have a low refractive index and low absorption coefficient in the THz region
Summary
The thin metallic or dielectric patterns on a frequency-selective surface (FSS) can reflect and transmit specific electromagnetic fields. Metallic THz metamaterials, designed with slits to enhance the THz field, have been introduced for specific frequency band transmission at high THz14,15. Carbon nanotubes and nanowires[21,22], parallel-plate waveguides[23,24] and metamaterials[25] have been used to make polarizers and modulators which operate in the THz region Because these devices are complicated to fabricate and suffer high refraction loss, they have had limited applications. An all-dielectric material such as quartz is efficient for measuring THz transmissions, because it has a lower refractive index and absorption[29] For these reasons, strong TM and TE resonance modes can be detected. The measurement results agreed very well with results from the simulations
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