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Nadell C, Fan K, Padilla W. Resonance-domain diffractive lens for the terahertz region. OPTICS LETTERS 2018; 43:2384-2387. [PMID: 29762598 DOI: 10.1364/ol.43.002384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 04/15/2018] [Indexed: 06/08/2023]
Abstract
Diffractive optics has long served as the basis of spectroscopic measurements of materials. Operation in the resonance domain further allows these elements to achieve high efficiency and polarization control. An effective grating theory is a practical tool for modeling such optics, and here we extend use of this theory to the terahertz region, experimentally demonstrating an all-dielectric binary off-axis diffractive lens. We achieve a high-efficiency, polarization-independent optic that both focuses and disperses terahertz light, suggesting potential applications in pharmaceutical, security, and semiconductor imaging.
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Jia D, Tian Y, Ma W, Gong X, Yu J, Zhao G, Yu X. Transmissive terahertz metalens with full phase control based on a dielectric metasurface. OPTICS LETTERS 2017; 42:4494-4497. [PMID: 29088196 DOI: 10.1364/ol.42.004494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/03/2017] [Indexed: 06/07/2023]
Abstract
In this paper, we report a transmissive terahertz (THz) metalens based on a dielectric metasurface that consists of periodically arranged sub-wavelength silicon cross resonators with a spatially hyperboloidal phase profile. By varying arm lengths of the cross resonators, we obtained a full 2π phase coverage with high transmission at target frequency. The fabricated metalens was experimentally demonstrated to focus a continuous THz beam to a spot with a full width at half-maximum of 630 μm at a focal length of 28 mm, which agrees well with the theoretical calculation. This device has potential for applications in THz imaging and communications, and our work can also easily be extended in the design of other planar THz components, such as beam deflectors or vortex plates.
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Szkudlarek K, Sypek M, Cywiński G, Suszek J, Zagrajek P, Feduniewicz-Żmuda A, Yahniuk I, Yatsunenko S, Nowakowska-Siwińska A, Coquillat D, But DB, Rachoń M, Węgrzyńska K, Skierbiszewski C, Knap W. Terahertz 3D printed diffractive lens matrices for field-effect transistor detector focal plane arrays. OPTICS EXPRESS 2016; 24:20119-20131. [PMID: 27607620 DOI: 10.1364/oe.24.020119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present the concept, the fabrication processes and the experimental results for materials and optics that can be used for terahertz field-effect transistor detector focal plane arrays. More specifically, we propose 3D printed arrays of a new type - diffractive multi-zone lenses of which the performance is superior to that of previously used mono-zone diffractive or refractive elements and evaluate them with GaN/AlGaN field-effect transistor terahertz detectors. Experiments performed in the 300-GHz atmospheric window show that the lens arrays offer both a good efficiency and good uniformity, and may improve the signal-to-noise ratio of the terahertz field-effect transistor detectors by more than one order of magnitude. In practice, we tested 3 × 12 lens linear arrays with printed circuit board THz detector arrays used in postal security scanners and observed significant signal-to-noise improvements. Our results clearly show that the proposed technology provides a way to produce cost-effective, reproducible, flat optics for large-size field-effect transistor THz-detector focal plane arrays.
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Suszek J, Siemion AM, Błocki N, Makowski M, Czerwiński A, Bomba J, Kowalczyk A, Ducin I, Kakarenko K, Pałka N, Zagrajek P, Kowalski M, Czerwińska E, Jastrzebski C, Świtkowski K, Coutaz JL, Kolodziejczyk A, Sypek M. High order kinoforms as a broadband achromatic diffractive optics for terahertz beams. OPTICS EXPRESS 2014; 22:3137-3144. [PMID: 24663604 DOI: 10.1364/oe.22.003137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We discuss thin optical structures that allow chromatic aberrations to be avoided in the THz domain. The paper contains the theoretical considerations, computer modeling and experimental evaluation of the high order kinoform diffractive elements in the THz range. According to the obtained results application of the high order kinoforms enables broadband operation in the THz range.
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Imakita K, Kamada T, Fujii M, Aoki K, Mizuhata M, Hayashi S. Terahertz wire grid polarizer fabricated by imprinting porous silicon. OPTICS LETTERS 2013; 38:5067-5070. [PMID: 24281511 DOI: 10.1364/ol.38.005067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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.
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Sypek M, Makowski M, Hérault E, Siemion A, Siemion A, Suszek J, Garet F, Coutaz JL. Highly efficient broadband double-sided Fresnel lens for THz range. OPTICS LETTERS 2012; 37:2214-2216. [PMID: 22739859 DOI: 10.1364/ol.37.002214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Modern passive THz setups require effective optical elements with a large numerical aperture. Here we propose a new type of the optical element for THz applications, which is a broadband double-sided Fresnel-like lens with an optimized thickness. The optimization is performed to obtain a very low attenuation, low material cost, and small weight in the element media. It also provides achromatic properties for the assumed wavelength range. The experimental evaluation of the proposed diffractive lens by means of time-domain spectroscopy is presented and discussed.
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Affiliation(s)
- Maciej Sypek
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00 662 Warsaw, Poland
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Busch S, Scherger B, Scheller M, Koch M. Optically controlled terahertz beam steering and imaging. OPTICS LETTERS 2012; 37:1391-1393. [PMID: 22513696 DOI: 10.1364/ol.37.001391] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We propose a spatial modulator for terahertz waves based on light induced electron plasma in photo-active semiconductors. A two-dimensional array of computer controlled light is used to create free carries in bulk silicon, which results in a spatial modulation of the transmission at terahertz frequencies. This method not only exhibits a remarkable modulation depth over a broad frequency range but also allows for an optically controlled beam steering of terahertz waves by inducing virtual grating structures. In addition, we analyze the possibility of all-optically controlled terahertz imaging.
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Affiliation(s)
- Stefan Busch
- Fachbereich Physik, Philipps-Universität Marburg, Renthof 5, 35032, Marburg, Germany. ‑marburg.de
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Siemion A, Siemion A, Makowski M, Sypek M, Hérault E, Garet F, Coutaz JL. Off-axis metallic diffractive lens for terahertz beams. OPTICS LETTERS 2011; 36:1960-1962. [PMID: 21633415 DOI: 10.1364/ol.36.001960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A diffractive optical element for off-axis focusing of terahertz radiation is presented. It was designed in a nonparaxial regime and manufactured in a metal slab by laser cutting of curved stripes. The optical function of the structure includes focusing and deflecting the illuminating beam of a chosen frequency in a particular place. Therefore, the element acts as both a spatial and a spectral filter; hence it is especially suitable for separating the terahertz signal from a broadband thermal load in passive detection devices. The experimental evaluation of the proposed diffractive lens by means of time-domain spectroscopy is presented and discussed.
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Affiliation(s)
- Agnieszka Siemion
- Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00 662 Warsaw, Poland
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Heimbeck MS, Reardon PJ, Callahan J, Everitt HO. Transmissive quasi-optical Ronchi phase grating for terahertz frequencies. OPTICS LETTERS 2010; 35:3658-3660. [PMID: 21042382 DOI: 10.1364/ol.35.003658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A transmissive, square-wave Ronchi phase grating has been fabricated from the dielectric polytetrafluoroethylene to diffract an ~0.7 THz beam quasi-optically. When illuminated by a coherent, cw terahertz (THz) source, the spot separation of the ±1 diffractive orders and the diffraction efficiency were measured as a function of THz frequency and rotation angle. The grating performance depends sensitively on the refractive index, whose value can be measured with an accuracy limited by the fabrication precision. The use of these gratings for polarization-insensitive quasi-optical imaging and phased arrays is discussed.
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Affiliation(s)
- Martin S Heimbeck
- Army Aviation and Missile RD&E Center, Weapon Sciences Directorate, Redstone Arsenal, Alabama 35898, USA.
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Vedernikov VM, Dutov PM, Kokarev AI, Kir’yanov VP, Knyazev BA, Nikitin VG, Pal’chikova IG, Sametov AR, Stupak MF, Chugui YV, Chukanov VV. Diffractive elements for a free electron laser. ACTA ACUST UNITED AC 2010. [DOI: 10.3103/s8756699010040102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Saha SC, Ma Y, Grant JP, Khalid A, Cumming DRS. Imprinted terahertz artificial dielectric quarter wave plates. OPTICS EXPRESS 2010; 18:12168-12175. [PMID: 20588340 DOI: 10.1364/oe.18.012168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have developed low-loss polymer artificial dielectric quarter wave plates (QWP) operating at 2.6, 3.2 and 3.8 THz. The QWPs are imprinted on high density polyethylene (HDPE) using silicon masters. The grating period for the quarter wave plates is 60 microm. 330 microm, 280 microm and 230 microm deep gratings are used to obtain a pi/2 phase retardance between TE and TM polarization propagating through the QWPs. High frequency structure simulator (HFSS) was used to optimize the grating depth. Since the required grating depth is high, two plates, fixed in a back-to-back configuration were used for each QWP. A maximum aspect ratio (grating height/grating width) of 6.6 was used.
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Affiliation(s)
- Shimul C Saha
- Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G12 8LT, UK
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