1
|
Chiba K, Okatani T, Inomata N, Kanamori Y. Micro-fabricated Si subwavelength grating for frequency-domain THz beam steering covering the 0.3-0.5 THz frequency band. OPTICS EXPRESS 2023; 31:27147-27160. [PMID: 37710795 DOI: 10.1364/oe.492942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/11/2023] [Indexed: 09/16/2023]
Abstract
We designed and fabricated beam steering subwavelength grating (BS-SWG) with high efficiency, wide angles, and broadband beam steering in the terahertz (THz) range. Beam steering technology in the THz range by a fixed structure and frequency sweep has to date lacked a device combining high efficiency and a wide beam steering angle. A subwavelength structure using float zone Si, a low-loss dielectric, could combine both of these aspects, but no experimental demonstration in the THz range has been performed to our knowledge. The BS-SWG was designed with an efficiency of 0.708 at 0.4 THz and beam steering angles of -72.1°--34.8° by sweeping the incident frequency from 0.3 THz to 0.5 THz including the Beyond 5 G/6 G communication bands. An efficiency of 0.354 at 0.400 THz and beam steering angles of -74°--34° were experimentally achieved, demonstrating the potential of high-efficiency, wide-angle beam steering for THz communications, imaging, and radar applications.
Collapse
|
2
|
Seifert JM, Hernandez-Cardoso GG, Koch M, Castro-Camus E. Terahertz beam steering using active diffraction grating fabricated by 3D printing. OPTICS EXPRESS 2020; 28:21737-21744. [PMID: 32752446 DOI: 10.1364/oe.399376] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
In this article, we propose variable-period diffraction gratings for terahertz frequencies. The design, fabrication and characterization of such devices are presented. Our measurements show the possibility to actively shift of the deflection angle for each frequency using this device. We also demonstrated that, when driven by a speaker, these variable gratings can be used for active beam steering with potential application in terahertz communications.
Collapse
|
3
|
Wide Field-of-view and Broadband Terahertz Beam Steering Based on Gap Plasmon Geodesic Antennas. Sci Rep 2017; 7:41642. [PMID: 28134324 PMCID: PMC5278544 DOI: 10.1038/srep41642] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/23/2016] [Indexed: 12/03/2022] Open
Abstract
Despite a plethora of applications ranging from wireless communications to sensing and spectroscopy, the current terahertz beam steering technologies suffer from tremendous insert loss, stringent control of electric bias, limited scanning angle, relatively complicated configuration and narrow operation bandwidth, preventing further practical application. We propose and demonstrate a conceptually new approach for terahertz beam steering by virtue of gap plasmon geodesic antennas. By adjusting the geometric dimension of the gap plasmon geodesic antennas, all gap plasmon modes add coherently along a peculiar direction that depends on the geodesic mean surface. Consequently, high directive beams are generated through the antenna, whose direction could be changed within a wide-angle range spanning ±45° by lateral motion of the feed. Furthermore, an assembled antenna structure consisting of four-element geodesic antennas array is proposed for full 360° beam steering, which can operate in a broadband range from 0.8 THz to 1.2 THz.
Collapse
|
4
|
Wang X, Deng Y, Li Q, Huang Y, Gong Z, B Tom K, Yao J. Excitation and propagation of surface plasmon polaritons on a non-structured surface with a permittivity gradient. LIGHT, SCIENCE & APPLICATIONS 2016; 5:e16179. [PMID: 30167135 PMCID: PMC6059887 DOI: 10.1038/lsa.2016.179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 05/11/2023]
Abstract
Accompanied by the rise of plasmonic materials beyond those based on noble metals and the development of advanced materials processing techniques, it is important to understand the plasmonic behavior of materials with large-scale inhomogeneity (such as gradient permittivity materials) because they cannot be modeled simply as scatterers. In this paper, we theoretically analyze the excitation and propagation of surface plasmon polaritons (SPPs) on a planar interface between a homogeneous dielectric and a material with a gradient of negative permittivity. We demonstrate the following: (i) free-space propagating waves and surface waves can be coupled by a gradient negative-permittivity material and (ii) the coupling can be enhanced if the material permittivity variation is suitably designed. This theory is then verified by numerical simulations. A direct application of this theory, 'rainbow trapping', is also proposed, considering a realistic design based on doped indium antimonide. This theory may lead to various applications, such as ultracompact spectroscopy and dynamically controllable generation of SPPs.
Collapse
Affiliation(s)
- Xi Wang
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Yang Deng
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Qitong Li
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Yijing Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Zilun Gong
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Kyle B Tom
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| |
Collapse
|
5
|
Lee E, Seo IC, Lim SC, Jeong HY, Jun YC. Active switching and tuning of sharp Fano resonances in the mid-infrared spectral region. OPTICS EXPRESS 2016; 24:25684-25696. [PMID: 27828504 DOI: 10.1364/oe.24.025684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We propose and analyze a scheme for active switching and spectral tuning of mid-infrared Fano resonances. We consider dielectric resonators made of semiconductor cylinder arrays and block pairs, and theoretically investigate their optical response change due to carrier generation. Owing to sharp optical resonances in these structures and large dielectric constant variations with carrier densities, the significant spectral tuning of Fano resonances is achievable. Furthermore, selective optical pumping in coupled semiconductor structures can even enable dynamic switching of Fano resonances. This leads to a drastic change in the scattering spectra as well as in the near-field intensity. We also observe a stark difference between Fano resonances in cylinder arrays and block pairs. To understand this unusual behavior, we adopt the two coupled oscillator model, and extract the relevant Fano resonance parameters that explain this difference. Our findings and in-depth analyses can be useful for molecular sensors and switching devices in the technologically important mid-infrared spectral region.
Collapse
|
6
|
Smaali R, Taliercio T, Centeno E. Photo-generated metasurfaces for resonant and high modulation of terahertz signals. OPTICS LETTERS 2016; 41:3900-3903. [PMID: 27519118 DOI: 10.1364/ol.41.003900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We theoretically demonstrate resonant modulation of terahertz (THz) waves with photo-designed metasurfaces. Our approach bypasses the short penetration length issue of the optical pump that prevents photo-generated thick metamaterials. We propose a three-layer semiconductor system of subwavelength thickness that presents 100% modulation of the reflection (or absorption) spectra at around 1 THz when optically actuated. This resonant modulation can be dynamically monitored at high frequency by the optical pump on a broad range of frequencies of Δν/ν=100%. Appropriate 2D photo-printed patterns make the system polarization insensitive and operational for a wide range of incident angles up to 65°.
Collapse
|
7
|
Orazbayev B, Beruete M, Khromova I. Tunable beam steering enabled by graphene metamaterials. OPTICS EXPRESS 2016; 24:8848-8861. [PMID: 27137318 DOI: 10.1364/oe.24.008848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. The effective refractive index of such metamaterials can be manipulated by changing the chemical potential of each graphene layer. This can arbitrarily tailor the spatial distribution of the phase of the transmitted beam, providing mechanisms for active beam steering. Three different beam steerer (BS) designs are discussed: a graded-index (GRIN) graphene-based metamaterial block, an array of metallic waveguides filled with graphene-dielectric metamaterial and an array of planar waveguides created in a graphene-dielectric metamaterial block with a specific spatial profile of graphene sheets doping. The performances of the BSs are numerically analyzed, showing the tunability of the proposed designs for a wide range of output angles (up to approximately 70°). The proposed graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.
Collapse
|