Terahertz frequency laser paves the way for better sensing, imaging and communications
The terahertz frequency range – which sits in the middle of the electromagnetic spectrum between microwaves and infrared light — offers the potential for high-bandwidth communications, ultrahigh-resolution imaging, precise long-range sensing for radio astronomy, and much more.
But this section of the electromagnetic spectrum has remained out of reach for most applications. That is because current sources of terahertz frequencies are bulky, inefficient, have limited tuning or have to operate at low temperature.
Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), in collaboration with MIT and the U.S. Army, have developed a compact, room temperature, widely tunable terahertz laser.
“This laser outperforms any existing laser source in this spectral region and opens it up, for the first time, to a broad range of applications in science and technology,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and co-senior author of the paper.
“There are many needs for a source like this laser, things like short range, high bandwidth wireless communications, very high-resolution radar, and spectroscopy,” said Henry Everitt, Senior Technologist with the U.S. Army CCDC Aviation & Missile Center and co-senior author of the paper.
Everitt is also an Adjunct Professor of Physics at Duke University.
While most electronic or optical terahertz sources use large, inefficient and complex systems to produce the elusive frequencies with limited tuning range, Capasso, Everitt and their team took a different approach.
To understand what they did, let’s go over some basic physics of how a laser works.
In quantum physics, excited atoms or molecules sit at different energy levels — think of these as floors of a building. In a typical gas laser, a large number of molecules are trapped between two mirrors and brought to an excited energy level, aka a higher floor in the building. When they reach that floor, they decay, fall down one energy level and emit a photon. These photons stimulate the decay of more molecules as they bounce back and forth leading to amplification of light. To change the frequency of the emitted photons, you need to change the energy level of the excited molecules.
So, how do you change the energy level? One way is to use light. In a process called optical pumping, light raises molecules from a lower energy level to a higher one — like a quantum elevator. Previous terahertz molecular lasers used optical pumps but they were limited in their tunability to just a few frequencies, meaning the elevator only went to a small number of floors.
The breakthrough of this research is that Capasso, Everitt and their team used a highly tunable, quantum cascade laser as their optical pump. These powerful, portable lasers, co-invented by Capasso and his group at Bell Labs in the 1990s, are capable of efficiently producing widely tunable light. In other words, this quantum elevator can stop at every floor in the building.
The theory to optimize the operation of the new laser was developed by Steven Johnson, Professor of Applied Mathematics and Physics at MIT, his graduate student Fan Wang and Everitt.
“Molecular THz lasers pumped by a quantum cascade laser offer high power and wide tuning range in a surprisingly compact and robust design,” said Nobel laureate Theodor Hänsch of the Max Planck Institute for Quantum Optics in Munich, who was not involved in this research. “Such sources will unlock new applications from sensing to fundamental spectroscopy.”
“What’s exciting is that concept is universal,” said Paul Chevalier, a postdoctoral fellow at SEAS and first author of the paper. “Using this framework, you could make a terahertz source with a gas laser of almost any molecule and the applications are huge.”
The researchers combined the quantum cascade laser pump with a nitrous oxide — aka laughing gas–laser.
“By optimizing the laser cavity and lenses, we were able to produce frequencies spanning nearly 1 THz,” said Arman Amirzhan, a graduate student in Capasso’s group and co-author of the paper.
“This result is one of a kind,” said Capasso. “People knew how to make a terahertz laser before but couldn’t make it broadband. It wasn’t until we began this collaboration, after a serendipitous encounter with Henry at a conference, that we were able to make the connection that you could use a widely tunable pump like the quantum cascade laser.”
This laser could be used in everything from improved skin and breast cancer imaging to drug detection, airport security and ultrahigh-capacity optical wireless links.
“I’m particularly excited about the possibility of using this laser to help map the interstellar medium,” said Everitt. “Molecules have unique spectral fingerprints in the terahertz region, and astronomers have already begun using these fingerprints to measure the composition and temperature of these primordial clouds of gas and dust. A better ground-based source of terahertz radiation like our laser will make these measurements even more sensitive and precise.”
The Latest on: Molecular THz lasers
- Ion beams mean a quantum leap for color-center qubitson April 28, 2021 at 12:15 pm
A technique developed by Berkeley Lab's Molecular Foundry measured color centers ... In the future, they might be made using compact laser-plasma accelerators like the ones being developed at ...
- Experimental Researchon April 18, 2021 at 6:02 am
Professor Di Bartolo's Group – Solid-state spectroscopy of laser-type materials, luminescence spectroscopy, flash photolysis and molecular spectroscopy ... using a combination of transport, Infrared, ...
- Ultrafast Bond Softening in Bismuth: Mapping a Solid's Interatomic Potential with X-rayson April 6, 2021 at 5:00 pm
A 50-nm-thick bismuth film grown by molecular beam epitaxy with a (111) surface orientation (14) was excited at room temperature by near-infrared pulses [(70 fs full width at half maximum (FWHM)] ...
- Potential new applications from ultrathin terahertz sourceon April 1, 2021 at 3:53 am
Ultrafast lasers at the University of Sussex EPic Lab ... but without being harmful. Terahertz imaging makes it possible to observe the molecular composition of objects and distinguish between ...
- Scientists develop ultra-thin terahertz sourceon March 30, 2021 at 8:57 am
Terahertz imaging makes it possible to 'see' the molecular composition of objects ... grade semiconductor with two different types of lasers light, each oscillating at different frequency or ...
- Laser Technique Could Enable Discovery of New Functional Materialson March 25, 2021 at 5:00 pm
For the first time ever, scientists have induced permanent changes in the conformation of a polymer using a terahertz laser--a discovery that could ... why the molecules rearrange without breaking the ...
- RIKEN Center for Advanced Photonics Terahertz Quantum Device Research Teamon August 13, 2020 at 9:05 pm
and Hirayama, H.: "Development of terahertz quantum cascade laser based on III-nitride semiconductors" The Review of Laser Engineering, Vol. 39, No. 10, pp. 769-774 (2011). 6.Terashima, W. and ...
- Spectroscopic terahertz imaging probes the inner structures of 0D-3D nanomaterialson August 10, 2020 at 10:06 pm
Terahertz time-domain scanning technology provides camera ... 1 These 0D materials do not form a molecular network of multidimensionality, but remain as a nano-dimensional entity, with a size smaller ...
- Recent Ph.D. Recipientson June 2, 2020 at 1:26 pm
Postdoctoral Researcher, Laser & Plasma Technologies ... Yuanyuan Huang, "Effects of Molecular Motion on Deuteron Magic Angle Spinning NMR Spectra," Advisor: Robert Vold. Ph.D. program in Finance, ...
via Bing News
The Latest on: Terahertz laser
- Worldwide Terahertz Radiation Devices Industry to 2026 - Growth in Global Demand for Precise Security Systems, Defense, and Medical Sectors is Drivingon April 28, 2021 at 1:57 am
The "Terahertz Radiation Devices Market - Growth, Trends, COVID-19 Impact, and Forecasts (2021 - 2026)" report has been added to ResearchAndMarkets.com's offering. The Terahertz Radiation Devices ...
- Compact ultrafast fiber lasers enable applications in new spaceson April 21, 2021 at 7:18 am
Fiber-based ultrafast laser platforms enable medical and industrial applications from cancer diagnosis to terahertz imaging and 3D nanoprinting.
- Global Metamaterial Market (2021 to 2026) - Use of Metamaterials in Solar Power Systems Presents Opportunitieson April 14, 2021 at 4:11 am
CONTACT: ResearchAndMarkets.com Laura Wood, Senior Press Manager [email protected] For E.S.T Office Hours Call 1-917-300-0470 For U.S./CAN Toll Free Call 1-800-526-8630 For GMT Office ...
- The Worldwide Metamaterial Industry is Projected to Reach $1.4 Billion by 2026 at a CAGR of 36.7% from 2021 - ResearchAndMarkets.comon April 12, 2021 at 9:23 am
The variety in design functionalities, anti-laser coating application ... the metamaterial market has been segmented into electromagnetic, terahertz, photonic, tunable, frequency selective ...
- The Worldwide Metamaterial Industry is Projected to Reach $1.4 Billion by 2026 at a CAGR of 36.7% from 2021 - ResearchAndMarkets.comon April 12, 2021 at 9:21 am
The metamaterial market was valued at USD 305 million in 2021 and is projected to reach USD 1,457 million by 2026. It is expected to grow at a CAGR of 36.7% during the forecast period. The variety in ...
- A 300-GHz low-cost high-gain fully metallic Fabry–Perot cavity antenna for 6G terahertz wireless communicationson April 8, 2021 at 3:49 am
The antenna is fabricated using laser-cutting brass technology ... For verification, the proposed sub-terahertz (THz) FPC antenna prototype was developed, fabricated, and measured.
- Electromagnetic microwave generation by acoustic vibrations gives rise to nanoradiophotonicson April 8, 2021 at 3:21 am
Laser radiation of the optical range implements ... particles is very promising for the creation of microwave and terahertz sources. The specific spectral range of the electromagnetic radiation ...
- Metamaterial Market Worth $1,457 Million by 2026on April 1, 2021 at 4:21 pm
Northbrook, IL -- (SBWIRE) -- 04/01/2021 -- According to the new market research report "Metamaterial Market by Material Type (Electromagnetic, Terahertz, Photonic, Tunable, FSS, and others ...
via Bing News