Query: Resonant metamaterial detectors based on THz quantum-cascade structures

Candidate papers:

abstract: We present the design, fabrication and characterisation of an intersubband detector employing a resonant metamaterial coupling structure. The semiconductor heterostructure relies on a conventional THz quantum cascade laser design and is operated at zero bias for the detector operation. The same active region can be used to generate or detect light depending on the bias conditions and the vertical confinement. The metamaterial is processed directly into the top metal contact and is used to couple normal incidence radiation resonantly to the intersubband transitions. The device is capable of detecting light below and above the reststrahlenband of gallium arsenide corresponding to the mid infrared and THz spectral region.
author_names: Alexander Benz

Michael Krall

Stefan Schwarz

Daniel R Dietze

Hermann Detz

A M Andrews

Werner Schrenk

Gottfried Strasser

Karl Unterrainer
title: Resonant metamaterial detectors based on THz quantum cascade structures
venue: Scientific reports
year: 2014

abstract: We present the design, fabrication and characterization of a resonant metamaterial detector based on a THz quantum cascade laser. The same active region can be used to generate and detect the light leading to miniaturized and integrated optical systems in the THz spectral range.
author_names: Alexander Benz

Stefan Schwarz

Michael Krall

Daniel R Dietze

Martin Brandstetter

Christoph Deutsch

Karl Unterrainer

Hermann Detz

Aaron Maxwell Andrews

Werner Schrenk

Gottfried Strasser
title: Resonant Metamaterial Detectors Utilizing THz Quantum Cascade Lasers
year: 2012

abstract: Imaging detector research on terahertz (1 THz=1012Hz) wavelength region is a hot topic in recent years. So far, the terahertz wave has shown considerable application potential in advanced imaging of some special targets1. The terahertz imaging has a relatively high resolution correspondent to common radio frequency imaging. It takes object surface shape and internal structure information2, which can not be captured by current mature optics imaging means or conventional infrared imaging methods. However, for a long time, due to the lack of effective terahertz detection techniques3 as well as most materials in nature inherently do not respond to THz radiation, or demonstrate a very weak response even not be utilized, it limits the development of terahertz theory and related technologies and applications especial in the terahertz detection fields, and thus leading to the progress and applications in THz regime lagging behind the rapid development of other electromagnetic spectrum. To realize the useful potential detecting applications of THz radiation, considerable efforts are underway for filling the 'THz gap' Some new type of materials such as typical metamaterial are really needed for constructing detecting architectures. Metamaterials4, which are artificially structured material, consists of subwavelength metallic resonators within or onto a dielectric or semiconducting substrate. Research and applications5,6 show that they already exhibit attractive electromagnetic properties, which are not available in naturally materials. Therefore, they can be used to enhance the optoelectronic response ability so as to efficiently manipulate, control, and detect electromagnetic radiation by particularly designed metamaterial micro nano structure. In addition, by scaling their size, we can scale their response from radio frequency to optical wavelength region, which means we can design metamaterials detector operated at desired frequency in a very wide frequency range, for example from UV IR Microwave RF, but in THz region is our key topic content in this paper. As demonstrated that metamaterials can be used to remarkably response incident THz radiation with both electric and magnetic resonant mode7, metamaterials micro nano structures are potential for future THz detection. By constructing metamaterials detectors for relatively wide THz wave, we can realize THz sensing and further imaging. In this paper, we design and simulate an electrically resonant terahertz metamaterial sensing unit. This kind of metamaterial micro nano structure can present an obvious response at 0.78 THz with a strong electrical resonant at the split ring resonator(SRR) gap, and thus provides a possibility to obtain the electrical signal so as to achieve THz sensing. By analyzing the simulation results, we summarize the feasibility of terahertz detection, and come out a layout of terahertz detector by scaling the size of metamaterial detector unit, we can obtain unit detector architecture that also resonant at other frequencies and finally lead to realize multispectral imaging.
author_names: Hongwu Ji

Jun Luo

Xinyu Zhang

Hongshi Sang

Changsheng Xie
title: Modeling and simulation of THz detectors based on electrical resonant metamaterial micro nano structures
venue: Other Conferences
year: 2013

abstract: In order to understand the formation of massive young stars, observation of a major coolant of dense interstellar medium, neutral atomic oxygen which has a fine structure line at 4.7448 THz, is an important task. It requires high sensitivity and high resolution spectroscopy systems in the terahertz (THz) frequency range. One of such systems is in the Stratospheric Observatory For Infrared Astronomy (SOFIA) It essentially requires stable local oscillator (LO) source for heterodyne detection. Therefore, we explore a field effect transistor based THz detector (TeraFET) with an integrated resonant patch antenna fabricated in commercially available standard 90 nm CMOS technology. At 4.75 THz, the detector exhibits an area normalized minimal noise equivalent power (NEP) of 404 pW/Hz and a maximum responsivity of 75 V/W where the effective area is 1750 mm2 and directivity reaches 7.4 dBi. These sensitivity and responsivity values contributes to the state of the art for room temperature electronic detectors operating at around 4.7 THz. We demonstrate experimentally, that the TeraFET detector can monitor the intensity of THz QCL radiation using only a small fraction of the beam power with S/N ratio of 40 dB and does not require chopping and could be employed in a heterodyne instrument.
author_names: Kestutis Ikamas

Maris Bauer

Jonas Matukas

Alvydas Lisauskas

Heiko Richter

Viktor Krozer

Heinz-Wilhelm Hubers

Hartmut G Roskos
title: Field Effect Transistor Based Detector for Measuring Power Fluctuations of 4 75 THz Quantum Cascade Laser Generated Radiation
year: 2018

abstract: Heterodyne spectroscopy of molecular rotational lines and atomic fine structure lines is a powerful tool in astronomy and planetary research. It allows for the study of the chemical composition, the evolution, and the dynamical behaviour of astronomical objects such as molecular clouds and star forming regions. For frequencies beyond 2 THz, SOFIA, the Stratospheric Observatory for Infrared Astronomy, is currently the only platform which allows for heterodyne spectroscopy at these frequencies. One example is the OI fine structure line at 4.7 THz, which is a main target to be observed with GREAT, the German Receiver for Astronomy at Terahertz Frequencies, on board of SOFIA. We report on the development of a 4.7 THz local oscillator (LO) for the heterodyne spectrometer GREAT on SOFIA. The LO combines a quantum cascade laser (QCL) with a compact, low input power Stirling cooler. The 4.7 THz QCL is based on a hybrid design and has been developed for continuous wave operation, high output powers, and low electrical pump powers [1] Efficient carrier injection is achieved by resonant longitudinal optical phonon scattering. This design allows for an operating voltage below 6 V. The amount of generated heat complies with the cooling capacity of the Stirling cooler of 7 W at 65 K with 240 W of electrical input power [2] Frequency stabilization is achieved by locking the emission from the QCL to an absorption line of CH3OH using a pyroelectric detector and a PID control loop [3] The design of the LO and its performance in terms of output power, frequency accuracy, frequency stability, and beam profile as well as its implementation in GREAT will be presented. [1] L. Schrottke, M. Wienold, R. Sharma, X. Lu, K. Biermann, R. Hey, A. Tahraoui, H. Richter, H. W. Hubers, H. T. Grahn, Semicond. Sci. Technol. 28, 03511 (2013) [2] H. Richter, M. Greiner Bar, S. G. Pavlov, A. D. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. T. Grahn, and H. W. Hubers, Opt. Express 18, 1017710187 (2010) [3] H. Richter, S. G. Pavlov, A. D. Semenov, L. Mahler, A. Tredicucci, H. E. Beere, D. A. Ritchie, and H. W. Hubers, Appl. Phys. Lett. 96, 071112 (2010)
author_names: Heiko Richter

Alexej D Semenov

M Wienold

Lutz Schrottke

Klaus Biermann

Holger T Grahn

Heinz-Wilhelm Hubers
title: A 4.7 THz quantum cascade laser as local oscillator for the GREAT heterodyne spectrometer on SOFIA
year: 2014

abstract: Abstract The electromagnetic response of the reported metamaterial is usually fixed, which greatly limits practical applications. Microstructural reconfiguration produces a drastic and dynamic controllability in metamaterials response that typically depend on shape, size, and distribution of metaatoms. Periodic rotatable double split resonant rings (DSRRs) structured on an ultrathin dielectric are adopted to design a micromechanical tunable 3 dimensional metamaterial (MT3DM) The powerful tunability quantified by transmissivity is conveniently achieved by mechanically changing location of gap in inner split ring. Modulation of transmissivity amplitude, resonance frequency, and band width reaches 54.41 dB, 0.31 THz, and 0.08 THz, respectively. The microstructure, equivalent circuit model, and reconfiguration mechanism of the proposed MT3DM are deeply discussed. The adjustable resonance can be easily scaled to the entire spectrum by geometrically regulating. Based on the powerful controllability, the proposed MT3DM can by widely applied in biochemical sensing, function materials, and electromagnetic devices including antenna, switch, absorber, and detector.
author_names: Zeng Qu

Yong Zhang

Binzhen Zhang
title: A micromechanical tunable 3D metamaterial based on periodic rotatable double split resonant rings
year: 2018

abstract: We provide an analysis of the electromagnetic modes of three dimensional metamaterial resonators in the THz frequency range. The fundamental resonance of the structures is fully described by an analytical circuit model, which not only reproduces the resonant frequencies but also the coupling of the metamaterial with an incident THz radiation. We also demonstrate the contribution of the propagation effects, and show how they can be reduced by design. In the optimized design, the electric field energy is lumped into ultra subwavelength (l/100) capacitors, where we insert a semiconductor absorber based on the collective electronic excitation in a two dimensional electron gas. The optimized electric field confinement is exhibited by the observation of the ultra strong light matter coupling regime, and opens many possible applications for these structures in detectors, modulators and sources of THz radiation.
author_names: Mathieu Jeannin

Djamal Gacemi

Angela Vasanelli

Lianhe Li

Alexander Giles Davies

Edmund Linfield

Giorgio Biasol

Carlo Sirtori

Yanko Todorov
title: Quasi static and propagating modes in three dimensional THz circuits.
venue: Optics express
year: 2020

abstract: The inherent limitations of metal based metamaterials are the key factors limiting the rapid development of the field of flexible terahertz metamaterials. The advantages of carbon nanotube based materials and devices in terms of weight, cost, and flexibility of free bending, make them of great use for flexible terahertz metamaterials and devices. Here, a flexible terahertz metamaterial sensor, based on a subwavelength periodic array structure of carbon nanotube thin films, is reported. The proposed flexible metamaterial can achieve the surface plasmon resonance to generate local field enhancement phenomenon, resulting in enhanced resonance transmission peaks. We observed that the resonant frequency and amplitude modulation can be continuously adjusted when the device is subjected to a small external strain. In addition, we found that the terahertz transmission spectrum changes significantly when analytes or dielectric layers, with different refractive indices, thicknesses, or carrying pore defects, are added on the surface of the carbon nanotubes film or below the polyimide substrate of the flexible metamaterials sensor in the bent state. Our results show that these materials and designed device strategies will aid in developing new terahertz functional devices, such as strain sensors, biochemical sensors, curved surface defect detectors, and wearable terahertz imagers.
author_names: Suguo Chen
title: Carbon nanotube based flexible metamaterials for THz sensing
year: 2021

abstract: Terahertz (THz) photodetectors have attracted great attention from scientists worldwide for their application in security checking, biomedical treatment and astronomical observation of remote stars and distant galaxies. As a typical THz detector, extrinsic GaAs based photoconductive detector is facing critical technical bottlenecks in the epitaxial growth of sufficiently thick and high quality GaAs absorption layer. In this work, a novel THz photoconductive detector based on metamaterial/GaAs/electrode layer hybrid structure was designed and simulated. By setting the periodic split ring resonator (SRR) structure as 88 mm pitch with 8 mm width, the absorption peaks exist at the wavelength of about 142 and 367 mm, which originate from the resonant cavity and the SRR dipole resonance effect, and the novel device shows a significant enhancement compared with the conventional GaAs photoconductive detector. Thus, the necessary thickness of GaAs absorption layer is largely reduced, and the resonant absorption peak can be modulated by changing the thickness of absorption layer. This work provides a novel device structure which can solve the critical epitaxial growth bottleneck of GaAs photoconductive detector and used for the astronomical observation, security check, etc.
author_names: Yulu Chen

Xiong Yang

Wulin Tong

Bingbing Wang

Chuansheng Zhang

Haoxing Zhang

Yongshan Hu

Ming Pan

Xiaodong Wang
title: The simulation on absorption properties of metamaterial/GaAs/electrode layer hybrid structure based Terahertz photoconductive detector
venue: Optical and Quantum Electronics
year: 2019

abstract: Wide angle polarization insensitive triple band perfect metamaterial absorbers (PMAs) based on single resonators are investigated. Generally speaking, the single resonator can only generate an absorption peak induced by the excitation of a fundamental resonance. Here, the designed absorbers with a single cave ring resonator appear three perfect peaks for different polarization angles at 6.53 THz, 7.09 THz and 7.64 THz. For the case of the transverse electric (TE) mode, the resonant peaks are controlled by the angle of incidence. Compared with previous studies about angular stability, the absorptivity still exceeds 92% around 6.53THz even when the incident angle for the TE mode is up to 80deg. For the case of the transverse magnetic (TM) mode, the absorptance at 7.64 THz is still greater than 92% even up to 70deg. Simulated electric field (Ez) and magnetic field /H/ distributions indicate that perfect absorption arises from the excitation of the multipolar response and surface plasmons. Besides, the complementary structure also displays three absorption peaks. We have demonstrated that simple ultrathin PMA has good absorption stability under an oblique incidence up to 70deg at 2.62 THz, and that the resonance frequency at 2.62 THz is almost unchanged for the incident angle ranging from 0deg to 70deg. These proposed absorbers may be used in many applications, such as THz imaging, sensors, and detectors.
author_names: Xiutao Huang

Conghui Lu

Cancan Rong

Minghai Liu
title: Wide angle perfect metamaterial absorbers based on cave rings and the complementary patterns
year: 2018