Search query: Active terahertz metamaterial devices

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abstract: The development of artificially structured electromagnetic materials, termed metamaterials, has led to the realization of phenomena that cannot be obtained with natural materials. This is especially important for the technologically relevant terahertz (1 THz 1012 Hz) frequency regime; many materials inherently do not respond to THz radiation, and the tools that are necessary to construct devices operating within this range sources, lenses, switches, modulators and detectors largely do not exist. Considerable efforts are underway to fill this 'THz gap' in view of the useful potential applications of THz radiation. Moderate progress has been made in THz generation and detection; THz quantum cascade lasers are a recent example. However, techniques to control and manipulate THz waves are lagging behind. Here we demonstrate an active metamaterial device capable of efficient real time control and manipulation of THz radiation. The device consists of an array of gold electric resonator elements (the metamaterial) fabricated on a semiconductor substrate. The metamaterial array and substrate together effectively form a Schottky diode, which enables modulation of THz transmission by 50 per cent, an order of magnitude improvement over existing devices.
author_names: Hou-Tong Chen

Willie J Padilla

Joshua M O Zide

Arthur C Gossard

Antoinette J Taylor

Richard D Averitt
title: Active terahertz metamaterial devices
venue: Nature
year: 2006

abstract: A wide variety of optical phenomena rely on the near field manipulation and confinement of electromagnetic field in subwavelength metallic and dielectric resonators with applications ranging from the design of micro and nano scale photonic devices to super lenses and ultrasensitive sensors. In this invited paper, we present a discussion on controlling the metamaterial properties by active and passive manipulation of near field coupling in an array of split ring resonators. We show that near field coupling between the meta atoms could lead to resonance tuning, mode splitting, and ultrafast switching in passive and active resonators. The near field coupling schemes discussed here demonstrate the application possibilities of such structures towards the design of active switches, amplitude modulators, frequency agile behaviors, and slow light devices, particularly for the terahertz frequency regime, which still suffers from the shortage of practical devices required to bridge the so called "THz gap"
author_names: Dibakar Roy Chowdhury

Abul Kalam Azad

Weili Zhang

Ranjan Singh
title: Near Field Coupling in Passive and Active Terahertz Metamaterial Devices
venue: IEEE Transactions on Terahertz Science and Technology
year: 2013

abstract: We demonstrate THz metamaterials exhibiting either amplitude control, via carrier injection or depletion in the active semiconductor substrate or frequency control, via photoexcitation of carriers into active semiconducting materials incorporated into the sub wavelength metamaterial structure.
author_names: Hou-Tong Chen

John F O'Hara

Abul Kalam Azad

David Shrekenhamer

Willie J Padilla

Joshua M O Zide

Arthur C Gossard

Richard D Averitt

Antoinette J Taylor
title: Active Terahertz Metamaterial Devices
year: 2008

abstract: In the above named work [ibid, vol. 3, no. 6, pp. 783 790, Nov. 2013] the mention of a funding agency was inadvertently omitted in the Acknowledgment. The omitted text in the Acknowledgement section [1, p. 788] is provided here.
author_names: Dibakar Roy Chowdhury

Abul Kalam Azad

Wensheng Zhang

Rajdeep Singh
title: Corrections to "Near field coupling in passive and active teraHertz metamaterial devices"
year: 2014

author_names: Hou-Tong Chen
title: Active Terahertz metamaterial devices
year: 2010

author_names: Xiaoguang Zhao
title: Active metamaterial devices at terahertz frequencies
year: 2016

abstract: Abstract Arbitrarily controlling the reflection/transmission/absorption state of electromagnetic waves, especially their dynamical manipulation, is on high demand due to the growing development of practical optical devices and application systems. In this work, we present a scheme to dynamically manipulating terahertz wave reflection/transmission/absorption using the active metamaterial composed of a layer of metallic structural and two graphene sandwich structures as well as polymer spacers. By adjusting the Fermi level of graphene, this tunable metamaterial can achieve electronically reconfigurable terahertz reflection, transmission and absorption in a highly efficient manner. Furthermore, it also enables continuous dynamical modulation between any two among the three states. The presented metamaterial is a promising candidate for exploring active terahertz devices for dynamically controlling the state of light matter interactions and have potential applications in optoelectronic devices, wireless communication and frequency selective surface.
author_names: Yin Sheng Zhang

Yijun Feng

Junming Zhao
title: Graphene enabled active metamaterial for dynamical manipulation of terahertz reflection/transmission/absorption
year: 2020

abstract: Within the last years there has been a tremendous thrust into research and technology in the THz spectral region (broadly defined as 0.1 10 THz) mainly driven by the unique potential where this radiation finds applications in, such as imaging, spectroscopy and communication. In all these fields a fast, integrated and versatile platform for modulating light is required. Metamaterial/graphene devices fulfill all these requirements as their subwavelength nature lends itself naturally to strong light matter interaction, and therefore highly efficient and miniaturized devices. Graphene's unique properties, e.g. the large carrier concentration modulation, provide a large degree of compatibility with several architectures which can be exploited in a range of modulation or detection schemes. Finally, metamaterial/graphene devices realize a fast, versatile platform, which can be easily scaled to other frequencies, and adapted into amplitude, frequency, polarization and phase modulators, as well as integrated detectors, for the next generation of wireless communication.
author_names: Riccardo Degl'Innocenti

Stephen J Kindness

Nikita W Almond

Wladislaw Michailow

Philipp Braeuninger-Weimer

Stephan Hofmann

Harvey E Beere

David A Ritchie
title: Metamaterial/graphene active terahertz modulators
venue: 2019 IEEE MTT S International Wireless Symposium (IWS)
year: 2019

abstract: of "Active Metamaterial and Waveguide Devices with Applications in Terahertz Communications" by Nicholas J. Karl, Ph.D. Brown University, May 2018 This work was motivated by the need to demonstrate new capabilities in the terahertz frequency range for modulation, multiplexing and beam steering. Which is driven by the demand for wireless communication networks to operate at terahertz frequencies within the coming decade. A promising candidate to address these challenges is the active terahertz metasurface. This photonic component is based on a metamaterial that is tunable through the application of an external voltage bias. The metasurface is an array of metamaterial elements in a two dimensional grid, patterned on a semiconductor substrate. I present analytic and experimental evidence that these metasurface devices have good performance characteristics as diffractive modulators, which can reach up to 20 dB modulation depth at kilohertz switching speeds. I illustrate that the diffracted radiation has larger bandwidth than the amplitude resonance data predicts, which indicates that a combined amplitude phase modulation leads to broadband operation. To understand this behavior I characterize the metasurface using terahertz ellipsometry. The characterization of the active response of an electrically tunable metamaterial is an open problem worth studying. Having a good understanding of this behavior will help guide active metamaterial device design. I present experimental data and an ellipsometric model involving finiteelement method simulations. I find a relation between the voltage applied to the metamaterial and the epilayer conductivity, a useful result that can be used in device design. Finally I use this result to design a phase modulator device. In addition to metamaterials, I study a parallel plate waveguide based leaky wave antenna, which demonstrates multiplexing capability in the terahertz frequency range. Taking advantage of a phase matching condition in the dispersive TE1 waveguide mode, the leaky wave antenna can multiplex frequencies together, and demultiplex a broadband beam. I provide experimental and numerical evidence showing how the device functions, and demonstrate multiplexing and demultiplexing behavior. I show how this device has a large parameter space, describe a possible design scenario, and develop a strategy for multiplexing 6 channels of 20 GHz bandwidth each. Devices that exhibit these kinds of functionality will play a large role in the architecture of future terahertz wireless networks. Active Metamaterial and Waveguide Devices with Applications in Terahertz Communications By Nicholas Jason Karl A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the School of Engineering at Brown University Providence, Rhode Island May 2018 (c) 2018 by Nicholas J. Karl
author_names: Nicholas Karl
title: Active Metamaterial and Waveguide Devices with Applications in Terahertz Communications
year: 2018

abstract: Active control of terahertz waves is critical to the development of terahertz devices. Two dimensional materials with excellent optical properties provide more choices for opto electrical devices due to the advancement in their preparation technology. We proposed a hybrid structure of a metamaterial/monolayer MoS2/Si and investigated its optical properties in the terahertz range. The plasmon induced transparency (PIT) effect was observed in the transmission spectra, resulting from the near field coupling of two bright modes. According to the simulated results, this phenomenon confirmed its dependency on the length of the cutwire and the distance between DSSRs. Furthermore, an external optical field supported by a 1064 nm laser could exert a switch effect on the sample. The resonances of the PIT metamaterial disappeared when the optical power was further increased, as the excited carriers in the MoS2/Si substrate blocked the coupling effect. In addition, the experimental results indicated that the PIT metamaterial enhanced the interaction of infrared light with the monolayer MoS2/Si substrate.
author_names: Jie Ji

Siyan Zhou

Weijun Wang

Furi Ling

Jianquan Yao
title: Active control of terahertz plasmon induced transparency in the hybrid metamaterial/monolayer MoS2/Si structure.
venue: Nanoscale
year: 2019