Terahertz wire-grid polarizers with micrometer-pitch Al gratings.
ABSTRACT We fabricated a terahertz wire-grid polarizer consisting of a micrometer-pitch Al grating on a Si substrate by photolithography and wet etching. The ratio of TM and TE transmittances (extinction ratio) was over 35 dB at 0.5 THz. At the Brewster angle of the Si substrate, the polarization transmittance of a TM wave through the fabricated polarizer exceeded 95% and the extinction ratio was over 45 dB at approximately 1 THz. The fabricated polarizer has a higher extinction ratio than conventional free-standing terahertz wire-grid polarizers.
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ABSTRACT: In this paper, a chiral metamaterial (CMM) with triple-layer twisted split-ring resonators structure was proposed, which could exhibit a linear polarization conversion as well as asymmetric transmission only for forward and backward propagating linearly polarized waves in a broadband frequency range. The polariza- tion of broadband linearly polarized electromagnetic waves can be rotated in a speciﬁc direction by passing it through such a CMM slab with a thickness of about one-twelfth the operational center wavelength. Experiment and simulation calcula- tions are in good agreement, and the polarization conversion rate is above 90% in the frequency range of 5.5–11.1GHz. The physical mechanism of the broadband linear polarization conversion effect could be further illustrated by simulated electrical ﬁeld and surface current distributions.Journal of Electromagnetic Waves and Applications 08/2013; 27(14):1850. · 1.40 Impact Factor
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ABSTRACT: A terahertz (THz) wire-grid polarizer is fabricated by imprinting porous Si followed by oblique evaporation of Ag. We demonstrate that it works in a wide frequency region covering from 5 to 18 THz with the extinction ratio of 10 dB. The frequency region is much wider than that of THz wire-grid polarizers fabricated by conventional imprint lithography using organic materials. The result suggests that imprinting of porous Si is a promising fabrication technique to realize low-cost wire-grid polarizers working in the THz region.Optics Letters 12/2013; 38(23):5067-70. · 3.39 Impact Factor
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ABSTRACT: As investigations into potential applications of terahertz technology grow, there is an increasing need for improved terahertz optical components such as polarizers. To determine the optical properties of a sample accurately, the polarization properties of the light must also be known accurately. Many terahertz emitters will have both horizontal and vertical polarization components and often assumptions are made about device characteristics without measuring them-even the position of excitation beam on the photoconductive emitter can affect the resulting terahertz electric field and so the exact optical properties of a given device will vary depending on how they are configured. Polarizers operating at terahertz frequencies can be used to characterize the electric field accurately or remove unwanted components as long as the polarizer is of sufficiently high performance. In this paper we review the key properties of polarizers and look at recent advances in their design and development at terahertz frequenciesJournal of infrared, millimeter and terahertz waves 09/2013; 34(9):489-499. · 1.12 Impact Factor