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Strecker K, Otto M, Nagai M, O'Hara JF, Mendis R. Artificial dielectric beam-scanning prism for the terahertz region. Sci Rep 2023; 13:13793. [PMID: 37612366 PMCID: PMC10447526 DOI: 10.1038/s41598-023-41046-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/21/2023] [Indexed: 08/25/2023] Open
Abstract
We design and fabricate an artificial dielectric prism that can steer a terahertz beam in space and experimentally investigate its behavior. The artificial dielectric medium consists of a uniformly spaced stack of metal plates, electromagnetically equivalent to an array of parallel-plate waveguides operating in tandem. At an operating frequency of 0.3 THz, we observe a maximum beam deflection of 29°, limited by the precision of the available spacers. Spring-loading the spacers between the plates allow us to scan the beam continuously and dynamically over a range of 5°. The measured beam intensity maps at the input and output of the device reveal very good Gaussian beam quality and an estimated power efficiency of 71%. As a possible real-world application, we integrate the prism into the path of a free-space terahertz communication link and demonstrate unimpaired performance.
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Affiliation(s)
- Karl Strecker
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Matthew Otto
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Masaya Nagai
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - John F O'Hara
- School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Rajind Mendis
- Riverside Research, Open Innovation Center, Beavercreek, OH, 45431, USA.
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Shrestha R, Fang Z, Guerboukha H, Sen P, Hernandez-Cardoso GG, Castro-Camus E, Jornet JM, Mittleman DM. The effect of angular dispersion on THz data transmission. Sci Rep 2022; 12:10971. [PMID: 35768465 PMCID: PMC9243068 DOI: 10.1038/s41598-022-15191-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 06/20/2022] [Indexed: 11/09/2022] Open
Abstract
One of the key distinctions between legacy low-frequency wireless systems and future THz wireless transmissions is that THz links will require high directionality, to overcome the large free-space path loss. Because of this directionality, optical phenomena become increasingly important as design considerations. A key example lies in the strong dependence of angular radiation patterns on the transmission frequency, which is manifested in many different situations including common diffraction patterns and the emission from leaky-wave apertures. As a result of this effect, the spectral bandwidth at a receiver is nonlinearly dependent on the receiver’s angular position and distance from the transmitter. In this work, we explore the implications of this type of effect by incorporating either a diffraction grating or a leaky wave antenna into a communication link. These general considerations will have significant implications for the robustness of data transmissions at high frequencies.
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Affiliation(s)
- Rabi Shrestha
- School of Engineering, Brown University, Providence, RI, 02912, USA.
| | - Zhaoji Fang
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | | | - Priyangshu Sen
- Department of Electrical and Computer Engineering, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | | | - Enrique Castro-Camus
- Department of Physics, Philipps-Universität Marburg, Renthof 5, 35032, Marburg, Germany
| | - Josep M Jornet
- Department of Electrical and Computer Engineering, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
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Non-Destructive Porosity Measurements of 3D Printed Polymer by Terahertz Time-Domain Spectroscopy. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020927] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The porosity and inhomogeneity of 3D printed polymer samples were examined using terahertz time-domain spectroscopy, and the effects of 3D printer settings were analysed. A set of PETG samples were 3D printed by systematically varying the printer parameters, including layer thickness, nozzle diameter, filament (line) thickness, extrusion, and printing pattern. Their effective refractive indices and loss coefficients were measured and compared with those of solid PETG. Porosity was calculated from the refractive index. A diffraction feature was observed in the loss spectrum of all 3D printed samples and was used as an indication of inhomogeneity. A “sweet spot” of printer settings was found, where porosity and inhomogeneity were minimised.
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Guerboukha H, Amarasinghe Y, Shrestha R, Pizzuto A, Mittleman DM. High-volume rapid prototyping technique for terahertz metallic metasurfaces. OPTICS EXPRESS 2021; 29:13806-13814. [PMID: 33985109 DOI: 10.1364/oe.422991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
Terahertz technology has greatly benefited from the recent development and generalization of prototyping technologies such as 3D printing and laser machining. These techniques can be used to rapidly fabricate optical devices for applications in sensing, imaging and communications. In this paper, we introduce hot stamping, a simple inexpensive and rapid technique to form 2D metallic patterns that are suitable for many terahertz devices. We fabricate several example devices to illustrate the versatility of the technique, including metasurfaces made of arrays of split-ring resonators with resonances up to 550 GHz. We also fabricate a wire-grid polarizer for use as a polarizing beam splitter. The simplicity and low cost of this technique can help in rapid prototyping and realization of future terahertz devices.
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Amarasinghe Y, Mendis R, Shrestha R, Guerboukha H, Taiber J, Koch M, Mittleman DM. Broadband wide-angle terahertz antenna based on the application of transformation optics to a Luneburg lens. Sci Rep 2021; 11:5230. [PMID: 33664394 PMCID: PMC7970861 DOI: 10.1038/s41598-021-84849-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 02/22/2021] [Indexed: 11/18/2022] Open
Abstract
The design of antennas for terahertz systems remains a significant challenge. These antennas must provide very high gain to overcome significant free-space path loss, which limits their ability to broadcast or receive a beam over a wide angular range. To circumvent this limitation, here we describe a new device concept, based on the application of quasi-conformal transformation optics to the traditional Luneburg lens. This device offers the possibility for wide-angle beam steering and beam reception over a broad bandwidth, scalable to any frequency band in the THz range.
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Affiliation(s)
| | - Rajind Mendis
- Riverside Research, 2640 Hibiscus Way, Beavercreek, OH, 45431, USA
| | - Rabi Shrestha
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | | | - Jochen Taiber
- Philipps-Universität Marburg, Renthof 5, 35032, Marburg, Germany
| | - Martin Koch
- Philipps-Universität Marburg, Renthof 5, 35032, Marburg, Germany
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Siemion A. The Magic of Optics-An Overview of Recent Advanced Terahertz Diffractive Optical Elements. SENSORS 2020; 21:s21010100. [PMID: 33375221 PMCID: PMC7795556 DOI: 10.3390/s21010100] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/17/2020] [Accepted: 12/22/2020] [Indexed: 02/05/2023]
Abstract
Diffractive optical elements are well known for being not only flat but also lightweight, and are characterised by low attenuation. In different spectral ranges, they provide better efficiency than commonly used refractive lenses. An overview of the recently invented terahertz optical structures based on diffraction design is presented. The basic concepts of structure design together with various functioning of such elements are described. The methods for structure optimization are analysed and the new approach of using neural network is shown. The paper illustrates the variety of structures created by diffractive design and highlights optimization methods. Each structure has a particular complex transmittance that corresponds to the designed phase map. This precise control over the incident radiation phase changes is limited to the design wavelength. However, there are many ways to overcome this inconvenience allowing for broadband functioning.
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Affiliation(s)
- Agnieszka Siemion
- Faculty of Physics, Warsaw University of Technology, 75 Koszykowa, 00-662 Warsaw, Poland
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