Abstract-Terahertz luminescence and photoconductivity associated with the impurity electron transitions in GaAs/AlGaAs quantum wells

A D Kurnosova, I S Makhov,  D A Firsov, 

https://iopscience.iop.org/article/10.1088/1742-6596/1482/1/012019

The photoconductivity and photoluminescence spectra of GaAs/AlGaAs quantum wells doped with shallow donors are studied at low lattice temperatures. The optical electron transitions between the first electron subband and donor ground states, as well as between the excited and ground donor states, are revealed in the terahertz photoluminescence and photoconductivity spectra. The temperature evolution of the impurity-related photocurrent in the terahertz spectral range is also studied.

Abstract-Terahertz Detection with Perfectly-Absorbing Photoconductive Metasurface

Thomas Siday,  Polina Vabishchevich, Lucy Hale, Charles Harris, Shan Ting Shan, John Reno, Igal Brener, Oleg Mitrofanov,

https://www.osti.gov/pages/biblio/1515200

Terahertz (THz) photoconductive devices are utilized for generation, detection, and modulation of THz waves, and they rely on the ability to switch electrical conductivity on a subpicosecond time scale using optical pulses. Yet, fast and efficient conductivity switching with high contrast has been a challenge, because the majority of photoexcited charge carriers in the switch do not contribute to the photocurrent due to fast recombination. Here, we improve efficiency of electrical conductivity switching using a network of electrically connected nanoscale GaAs resonators, which form a perfectly absorbing photoconductive metasurface. We achieve perfect absorption without incorporating metallic elements, by breaking the symmetry of cubic Mie resonators. As a result, the metasurface can be switched between conductive and resistive states with extremely high contrast using an unprecedentedly low level of optical excitation. We integrate this metasurface with a THz antenna to produce an efficient photoconductive THz detector. The perfectly absorbing photoconductive metasurface opens paths for developing a wide range of efficient optoelectronic devices, where required optical and electronic properties are achieved through nanostructuring the resonator network.

Abstract-Room Temperature Amplification of Terahertz Radiation by Grating-Gate Graphene Structures

Stephane Boubanga-Tombet, Wojciech Knap, Deepika Yadav, Akira Satou, Dmytro B. But, Vyacheslav V. Popov, Ilya V. Gorbenko, Valentin Kachorovskii, Taiichi Otsuji

https://arxiv.org/abs/2003.09649

We report on experimental studies of terahertz (THz) radiation transmission through grating-gate graphene-channel transistor nanostructures and demonstrate room temperature THz radiation amplification stimulated by current-driven plasmon excitations. Specifically, with increase of the direct current (dc) under periodic charge density modulation, we observe a strong red shift of the resonant THz plasmon absorption, its complete bleaching, followed by the amplification and blue shift of the resonant plasmon frequency. Our results are, to the best of our knowledge, the first experimental observation of energy transfer from dc current to plasmons leading to THz amplification. We present a simple model allowing for the phenomenological description of the observed amplification phenomena. This model shows that in the presence of dc current the radiation-induced correction to dissipation is sensitive to the phase shift between THz oscillations of carrier density and drift velocity, and with increase of the current becomes negative, leading to amplification. The experimental results of this work as all obtained at room temperature, pave the way towards the new 2D plasmons based, voltage tuneable THz radiation amplifiers

Early Detection of COVID-19 virus using terahertz scanner and AI

http://theshillongtimes.com/2020/03/29/nehu-professor-in-team-developing-ai-scanner/

SHILLONG: Indian researchers including an associate professor from NEHU are working actively in developing an Artificial Intelligence (AI)-based T-Ray scanning unit to address the limitation of infrared thermal scanner in accurate and early detection of COVID-19 patients.
Dr. Moumita Mukherjee, Associate Dean, Adamas University (Kolkata), & formerly associated with DRDO centre and Dr Dinesh Bhatia, Associate Professor- Biomedical Engineering Department of North Eastern Hill University (NEHU), Shillong and their collaborative research group are working on a product which will be cost-effective, allowing quick diagnosis with accurate in screening and monitoring of mass population.
As per Mukherjee & Bhatia, the unique absorption fingerprint of T-Ray radiation in lungs and the contrast thermal image of affected and healthy lungs will help the doctors and paramedical staff to identify such cases at an early stage, when the patient is apparently asymptomatic and not showing any symptoms.
Their extensive research is showing a ray of hope in easy identification followed by safe monitoring of COVID-19 patients worldwide.  They acknowledge the support of their respective institutions for providing desired support to carry out this research.
Since Terahertz is non-ionizing in nature, its repetitive use in scanning / imaging for screening and monitoring will be harmless to the population and its users such doctors, paramedical staff and other security staff in the vicinity in comparison to using X Ray or CT scan device as both are considered to be ionizing in nature and can cause cancer if repeatedly used for testing on COVID-19 patients in future.
The use of terahertz (THz) device will be more effective in getting desired reliable information compared to the existing thermal scanners and is considered as the most exciting application offered by the THz technology due to its size, ease, cost-effectiveness, and portability of terahertz-imaging unit.

Abstract-Nanoplasma-enabled picosecond switches for ultrafast electronics

Mohammad Samizadeh Nikoo, Armin Jafari, Nirmana Perera, Minghua Zhu, Giovanni Santoruvo, Elison Matioli

Implementation of nanoplasma switches.

https://www.nature.com/articles/s41586-020-2118-y

The broad applications of ultrawide-band signals and terahertz waves in quantum measurements, imaging and sensing techniques, advanced biological treatments, and very-high-data-rate communications have drawn extensive attention to ultrafast electronics. In such applications, high-speed operation of electronic switches is challenging, especially when high-amplitude output signals are required. For instance, although field-effect and bipolar junction devices have good controllability and robust performance, their relatively large output capacitance with respect to their ON-state current substantially limits their switching speed8. Here we demonstrate a novel on-chip, all-electronic device based on a nanoscale plasma (nanoplasma) that enables picosecond switching of electric signals with a wide range of power levels. The very high electric field in the small volume of the nanoplasma leads to ultrafast electron transfer, resulting in extremely short time responses. We achieved an ultrafast switching speed, higher than 10 volts per picosecond, which is about two orders of magnitude larger than that of field-effect transistors and more than ten times faster than that of conventional electronic switches. We measured extremely short rise times down to five picoseconds, which were limited by the employed measurement set-up. By integrating these devices with dipole antennas, high-power terahertz signals with a power–frequency trade-off of 600 milliwatts terahertz squared were emitted, much greater than that achieved by the state of the art in compact solid-state electronics. The ease of integration and the compactness of the nanoplasma switches could enable their implementation in several fields, such as imaging, sensing, communications and biomedical applications.

A nanoscale device to generate high-power Terahertz waves

The nanoscale terahertz wave generator can be implemented on flexible substrates. (Image: EPFL / POWERlab)

https://www.nanowerk.com/nanotechnology-news2/newsid=54832.php

(Nanowerk News) Terahertz (THz) waves fall between microwave and infrared radiation in the electromagnetic spectrum, oscillating at frequencies of between 100 billion and 30 trillion cycles per second. These waves are prized for their distinctive properties: they can penetrate paper, clothing, wood and walls, as well as detect air pollution. THz sources could revolutionize security and medical imaging systems. What's more, their ability to carry vast quantities of data could hold the key to faster wireless communications.

THz waves are a type of non-ionizing radiation, meaning they pose no risk to human health. The technology is already used in some airports to scan passengers and detect dangerous objects and substances.

Despite holding great promise, THz waves are not widely used because they are costly and cumbersome to generate. But new technology developed by researchers at EPFL could change all that. The team at the Power and Wide-band-gap Electronics Research Laboratory (POWERlab), led by Prof. Elison Matioli, built a nanodevice (1 nanometer = 1 millionth of a millimeter) that can generate extremely high-power signals in just a few picoseconds, or one trillionth of a second, - which produces high-power THz waves.

The technology, which can be mounted on a chip or a flexible medium, could one day be installed in smartphones and other hand-held devices. The work first-authored by Mohammad Samizadeh Nikoo, a PhD student at the POWERlab, has been published in the journal Nature ("Nanoplasma-enabled picosecond switches for ultrafast electronics").

How it works

The compact, inexpensive, fully electric nanodevice generates high-intensity waves from a tiny source in next to no time. It works by producing a powerful "spark," with the voltage spiking from 10 V (or lower) to 100 V in the range of a picosecond. The device is capable of generating this spark almost continuously, meaning it can emit up to 50 million signals every second. When hooked up to antennas, the system can produce and radiate high-power THz waves.

The device consists of two metal plates situated very close together, down to 20 nanometers apart. When a voltage is applied, electrons surge towards one of the plates, where they form a nanoplasma. Once the voltage reaches a certain threshold, the electrons are emitted almost instantly to the second plate. This rapid movement enabled by such fast switches creates a high-intensity pulse that produces high-frequency waves.

Conventional electronic devices are only capable of switching at speeds of up to one volt per picosecond - too slow to produce high-power THz waves.

The new nanodevice, which can be more than ten times faster, can generate both high-energy and high-frequency pulses. "Normally, it's impossible to achieve high values for both variables," says Matioli. "High-frequency semiconductor devices are nanoscale in size. They can only cope with a few volts before breaking out. High-power devices, meanwhile, are too big and slow to generate terahertz waves. Our solution was to revisit the old field of plasma with state-of-the-art nanoscale fabrication techniques to propose a new device to get around those constraints."

According to Matioli, the new device pushes all the variables to the extreme: "High-frequency, high-power and nanoscale aren't terms you'd normally hear in the same sentence."

"These nanodevices, on one side, bring an extremely high level of simplicity and low-cost, and on the other side, show an excellent performance. In addition, they can be integrated with other electronic devices such as transistor. Considering these unique properties, nanoplasma can shape a different future for the area of ultra-fast electronics", says Samizadeh.

The technology could have wide-ranging applications beyond generating THz waves. "We're pretty sure there'll be more innovative applications to come," adds Matioli.

Source: Ecole Polytechnique Fédérale de Lausanne

Abstract-A Novel Low-Cost Frequency Selective Structure for Millimetre-Wave and Terahertz Applications

Amir Khurrum Rashid, Qingfeng Zhang,

https://ieeexplore.ieee.org/document/9038238

A very simple form of frequency selective structure is considered for millimetre-wave and terahertz (THz) applications. It consists of a two-dimensional periodic array of through-holes, which are drilled in a printed circuit board (PCB). Quality factor of this FSS can be easily controlled by the size of holes, and the separation among them. Unlike other reported millimetre-wave/THz FSS designs, the proposed structure does not require a silicon substrate and microfabrication chamber. Instead, it can be fabricated on a commonly available double-sided copper PCB, through a low-cost fabrication method.

New Metasurface Helps Make the Switch to Terahertz Frequencies

Image adapted with permission from Siday et al., “Terahertz detection with perfectly-absorbing photoconductive metasurface.” Nano Letters, 19, 2888-2896 (2019). Copyright 2020 American Chemical Society.

Graphic depicting a photoconductive metasurface. Each unit cell supports resonance of light on two axes of symmetry (labeled Hx and Hz) to enable perfect light absorption. The inset image shows a scanning electron micrograph of a terahertz detector.

A new photoconductive metasurface paves the way for smaller, more efficient terahertz detectors.

Researchers are finding promising new applications for terahertz radiation (between microwaves and infrared light). Terahertz radiation could lead to new capabilities in imaging, wireless communications, and other areas. To expand its use, we need new devices designed for terahertz frequencies. Those needs include switches that work in less than a thousandth of a second, have a high contrast between “off” and “on” states, and efficiently carry electrical charges. Researchers have developed a new metasurface—an artificial material only billionths of a meter thick—that does all three.

The Impact

The new highly efficient metasurface switch needs no metal or backing material. This means detectors using the switch would be smaller, thinner, more efficient, and require less power. That makes them lower in cost and easier to integrate into terahertz detectors for communications and imaging. Terahertz radiation has potential safety and other benefits compared to other frequencies.

Summary

Terahertz radiation is in the band of frequencies higher than microwaves but lower than infra-red light. Terahertz radiation is very safe, and technologies such as wireless communications and imaging systems may eventually use this frequency range. Researchers are therefore developing devices that can efficiently generate, detect, and modulate terahertz waves. A key technology for terahertz devices is an ultrafast photoconductive switch,a switch that would use light to change electrical conductivity between a highly resistive “off” state and a highly conductive “on” state in less than a picosecond (one trillionth of a second). To achieve this performance, these switches need high contrast in conductivity between the “on” and “off” states. Until recently, researchers have not been able to meet this requirement.

Now, researchers at the Center for Integrated Nanotechnologies, a Department of Energy Nanoscale Science Research Center, have solved that challenge. The researchers developed a perfectly absorbing ultrathin photoconductive metasurface. The metasurface is a network of tiny repeating structures called resonators. These connected resonators support magnetic dipole modes and can efficiently absorb light at a desired wavelength. They achieve perfect light absorption using two overlapping resonances with the correct symmetry. The resulting metasurface is a tenth of the thickness of the original photoconductive switch. The thinner the device, the greater the contrast between “off” and “on” states. The metasurface could be applied to applications such as efficient fast modulators, a critical component of modern communication systems, and smaller, more efficient terahertz detector arrays.

Funding

This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering and by Britain’s Engineering and Physical Sciences Research Council. Fabrication, optical, and some terahertz experiments were performed at the Center for Integrated Nanotechnologies (CINT), a Department of Energy Office of Science user facility.

Abstract-Discovery of the soft electronic modes of the trimeron order in magnetite

• Edoardo Baldini, 
• Carina A. Belvin, 
• Martin Rodriguez-Vega, 
• Ilkem Ozge Ozel, 
• Dominik Legut, 
• Andrzej Kozłowski, 
• Andrzej M. Oleś, 
• Krzysztof Parlinski, 
• Przemysław Piekarz, 
• José Lorenzana, 
• Gregory A. Fiete & 
• Nuh Gedik                                                         

  

  The trimeron order in magnetite and the experimental methodology.

                                                                                                                                       https://www.nature.com/articles/s41567-020-0823-y                                                                                                                                                                                                                                                                                    

The Verwey transition in magnetite (Fe3O4) is the first metal–insulator transition ever observed and involves a concomitant structural rearrangement and charge–orbital ordering. Owing to the complex interplay of these intertwined degrees of freedom, a complete characterization of the low-temperature phase of magnetite and the mechanism driving the transition have long remained elusive. It was demonstrated in recent years that the fundamental building blocks of the charge-ordered structure are three-site small polarons called trimerons. However, electronic collective modes of this trimeron order have not been detected to date, and thus an understanding of the dynamics of the Verwey transition from an electronic point of view is still lacking. Here, we discover spectroscopic signatures of the low-energy electronic excitations of the trimeron network using terahertz light. By driving these modes coherently with an ultrashort laser pulse, we reveal their critical softening and hence demonstrate their direct involvement in the Verwey transition. These findings shed new light on the cooperative mechanism at the origin of magnetite’s exotic ground state.

Dancing electrons solve a longstanding puzzle in the oldest magnetic material

Researchers confirmed the existence of electronic waves that are frozen at a transition temperature of 125 kelvins and start “dancing together” in a collective oscillating motion as the temperature is lowered. In this illustration, a red laser beam triggers the dance of the newly discovered electronic waves in magnetite.

Image: Ambra Garlaschelli

Physicists use extreme infrared laser pulses to reveal frozen electron waves in magnetite.

Sandi Miller

http://news.mit.edu/2020/dancing-electrons-solve-long-standing-puzzle-oldest-magnetic-material-0311

Magnetite is the oldest magnetic material known to humans, yet researchers are still mystified by certain aspects of its properties.

For example, when the temperature is lowered below 125 kelvins, magnetite changes from a metal to an insulator, its atoms shift to a new lattice structure, and its charges form a complicated ordered pattern. This extraordinarily complex phase transformation, which was discovered in the 1940s and is known as the Verwey transition, was the first metal-insulator transition ever observed. For decades, researchers have not understood exactly how this phase transformation was happening.

According to a paper published March 9 in Nature Physics, an international team of experimental and theoretical researchers discovered fingerprints of the quasiparticles that drive the Verwey transition in magnetite. Using an ultrashort laser pulse, the researchers were able to confirm the existence of peculiar electronic waves that are frozen at the transition temperature and start “dancing together” in a collective oscillating motion as the temperature is lowered.  

“We were investigating the mechanism behind the Verwey transition and we suddenly found anomalous waves freezing at the transition temperature” said MIT physics postdoc Edoardo Baldini, one of the lead authors on the paper. “They are waves made of electrons that displace the surrounding atoms and move collectively as fluctuations in space and time.”

This discovery is significant because no frozen waves of any kind had ever been found in magnetite. “We immediately understood that these were interesting objects that conspire in triggering this very complex phase transition,” says MIT physics PhD student Carina Belvin, the paper’s other lead author.

These objects that form the low-temperature charge order in magnetite are “trimerons,” three-atom building blocks. “By performing an advanced theoretical analysis, we were able to determine that the waves we observed correspond to the trimerons sliding back and forth,” explains Belvin.

“The understanding of quantum materials such as magnetite is still in its infancy because of the extremely complex nature of the interactions that create exotic ordered phases,” adds Baldini.  

The researchers suggest that the larger significance of this finding will impact the field of fundamental condensed matter physics, advancing the comprehension of a conceptual puzzle that has been open since the early 1940s. This work, led by MIT professor of physics Nuh Gedik, was made possible by the use of “ultrafast terahertz spectroscopy,” an advanced laser apparatus based on ultrashort pulses in the extreme infrared. Gedik says, “These laser pulses are as short as one millionth of one millionth of a second and allow us to take fast photographs of the microscopic world. Our goal now is to apply this approach to discover new classes of collective waves in other quantum materials.”

The measurements were performed with Ilkem Ozge Ozel PhD ’18 in the Department of Physics. Gedik and his group also collaborated with a team of theorists including MIT Affiliate Professor Gregory Fiete and researchers from Poland and Italy. This work was supported, in part, by the U.S. Department of Energy and the Gordon and Betty Moore Foundation.

LUNA Blog-Luna’s TeraMetrix THz equipment used to examine Da Vinci’s Last Supper

https://lunainc.com/lunas-terametrix-thz-equipment-examine-da-vincis-supper/

On October 21, 2019 at the request of the Museo del Cenacolo Vinciano (Milan, Italy), Polo Museale Regionale della Lombardia, Ministero per i beni e la attività culturali  and the Istituto Centrale per il Restauro (Rome, Italy), one of the most famous murals in the world, the Last Supper by Leonardo Da Vinci, was examined using terahertz (THz) and millimeter waves.

Terahertz imaging is particularly useful in examining the layer structure of the mural painting in fine detail without touching the mural.  Terahertz time-domain imaging done using the TeraMetrix T-Ray 5000 system provided internal layer structure information of the famous artwork.  This investigation provides insight into the preparation layers present under the mural itself.  The information from this type of imaging can also be important for preservation, if a certain layer is loose, prone to degradation or delaminated, then that area can be treated in a particular way, or the storage conditions can be changed to slow deterioration.  If anomalies are found (areas where the structure is different) it can be a result of earlier restorations.  Often little detailed information is available about restorations that might have happened hundreds of years ago.The National Institute of Information and Communications Technology (Japan) coordinated the project based on their experience in cultural heritage science research field in collaboration with the Istituto di Fisica Applicata “Nello Carrara” of the National Research Council (Florence, Italy).  Because lower frequencies can penetrate deeper into the wall, a millimeter wave system from Fraunhofer Institute for Industrial Mathematics (Kaiserslautern, Germany) was used as well.  

The first preliminary results were presented at the THz Workshop held in Kaiserslautern, Germany on March 3, 2020.

Abstract-High extinction ratio terahertz broadband polarizer based on the aligned Ni nanowire arrays

Wenfeng Xiang, Xiaowei Huang, Dong Li, Qingli Zhou, Haizhong Guo, and Junjian Li

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-45-7-1978

We present a broadband terahertz (THz) polarizer based on the stacks of aligned Ni nanowire (NW) arrays. We demonstrated that the polarizer has an extinction ratio of 58.8 dB and an average extinction ratio of 46.6 dB throughout a frequency range of 0.3–2.3 THz. Compared to carbon-nanotube and metallic wire-grid polarizers, our Ni-NW polarizers with rapid, reliable, low-cost fabrication processes are ideal candidates for emerging THz technologies.

© 2020 Optical Society of America

Abstract-Highly-efficient terahertz radiation generated by surface electrons from laser-foil interactions

Ke Hu, Longqing Yi

https://arxiv.org/abs/2003.08899

A novel scheme for generating powerful terahertz (THz) radiation based on laser-solid interactions is proposed. When a p-polarized femtosecond laser impinges obliquely on a plane solid target and the target partially blocks the laser energy, surface electrons are extracted out and accelerated by the laser fields, forming a low-divergence electron beam. A half-cycle THz radiation pulse is emitted simultaneously as the beam passes by the edge of the target, due to coherent diffraction radiation. Our particle-in-cell simulations show that the relativistic THz pulse can have an energy of a few tens of millijoule and the conversion efficiency can be over 1% with existing ∼J level femtosecond laser sources.

Abstract-Terahertz quantum sensing

 Björn Haase, Daniel Molter, Felix Riexinger, Mirco Kutas, Patricia Bickert,

https://advances.sciencemag.org/content/6/11/eaaz8065

Quantum sensing is highly attractive for accessing spectral regions in which the detection of photons is technically challenging: Sample information is gained in the spectral region of interest and transferred via biphoton correlations into another spectral range, for which highly sensitive detectors are available. This is especially beneficial for terahertz radiation, where no semiconductor detectors are available and coherent detection schemes or cryogenically cooled bolometers have to be used. Here, we report on the first demonstration of quantum sensing in the terahertz frequency range in which the terahertz photons interact with a sample in free space and information about the sample thickness is obtained by the detection of visible photons. As a first demonstration, we show layer thickness measurements with terahertz photons based on biphoton interference. As nondestructive layer thickness measurements are of high industrial relevance, our experiments might be seen as a first step toward industrial quantum sensing applications.

Abstract-Getting Ready for Terahertz Electronics

• Mladen Božani, 
• Saurabh Sinha, 

https://link.springer.com/chapter/10.1007/978-3-030-44398-6_7

In the opening sections of this book, terahertz waves (sometimes abbreviated THz waves) were briefly introduced as waves with frequencies in the range between 300 GHz and 3 THz, situated directly above the millimeter-wave range in the frequency spectrum. Although it is “millimeter-waves” that appear in the title of this book, the discussions on the topics explored in the previous six chapters would be incomplete without at least a one-chapter-long discussion on the part of the spectrum that has emerged as a natural extension of the said millimeter-wave spectrum.

Abstract-Enhanced terahertz imaging of electronic packaging materials with deconvolution algorithm

Chan Zheng;  Zheyu Song;  Shihan Yan;  Jingbo Liu;  Dongxiong Ling;  Dongshan Wei;  Jinyun Zhou

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11441/114410D/Enhanced-terahertz-imaging-of-electronic-packaging-materials-with-deconvolution-algorithm/10.1117/12.2547637.short

This paper proposes the deconvolution image restoration algorithm, which uses the point spread function constructed by the physical characteristics of the terahertz beam to reconstruct the terahertz image and improve the image resolution[1]. At the same time, by constructing a point spread function with different penetration depths in the sample, the effect of image chromatogram on the sample can also be achieved. The integrated circuit (IC) electronic package terahertz imaging results clearly show the spatial position of the pins, internal chips and defects of the electronic packages, and analyze a variety of failure defect types, which are <1% more than the actual size.

© (2020) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Abstract-Transforming terahertz plasmonics within subwavelength hole arrays into enhanced terahertz mission via Smith-Purcell effect

Zijia Yu, Yucheng Liu, and Weihao Liu

Schematics of the proposed coherent Smith-Purcell radiation (SPR) transformed from the electron-beam-excited SPs modes on the material surface and within the subwavelength holes. Here ‘SM’ and ‘HM’ denote surface-mode and hole-mode, respectively.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-7-9501

We illustrate the transformation of terahertz plasmonics within an array of rectangular sub-wavelength holes (RSHs) into coherent and enhanced terahertz emission via Smith-Purcell effect. The radiative plasmonic modes within each RSH of the array are successively excited by an free-electron beam, which then generate coherent radiation by constructive interference. Compared with the case without taking plasmonics into consideration, the radiation field intensity is enhanced by more than an order of magnitude, affording a promising way of developing high-power terahertz radiation. We perform detailed analysis of the plasmonic modes within the RSH by using the dielectric waveguide theory, and the results are verified by numerical simulations. The influences of the RSH parameters on the radiation properties are revealed and discussed.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Tesla-Scale Terahertz Magnetic Impulses

Shawn Sederberg, Fanqi Kong, and Paul B. Corkum

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.10.011063

Measuring the magnetic response of matter relies acutely on the degree to which a magnetic field source’s amplitude, spatial, and temporal character can be tailored. Magnetic fields are inseparable from light-matter interaction, yet due to the dominance of electric-field-induced effects in many systems, laser pulses have heretofore provided comparatively limited insight into the high-frequency magnetic response of matter. Conductors or superconductors arranged in a solenoidal configuration embody the state-of-the-art apparatus for generating spatially isolated magnetic fields, but the reliance on electrical circuitry limits the field amplitude, pulse brevity, and absolute timing of the generated fields. We transfer the concept of solenoidal currents commonly leveraged in electromagnets to photo-ionized electrons driven by moderately intense vector laser beams, in a scheme that does not require the laser mode to carry orbital angular momentum. We predict that this all-optical approach will enable magnetic fields exceeding 8 Tesla to be turned on within 50 femtoseconds using moderate laser intensities, an unprecedented combination of parameters that will open the possibility for ultrafast metrological techniques to be combined with intense, spatially isolated, magnetic fields.

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