Navigation Links
Researchers realize high-power, narrowband terahertz source at room temperature
Date:9/30/2011

Researchers at Northwestern University have developed a simpler way to generate single-chip terahertz radiation, a discovery that could soon allow for more rapid security screening, border protection, high sensitivity biological/chemical analysis, agricultural inspection, and astronomical applications.

The work, headed by Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science in the McCormick School of Engineering and Applied Science, was published Sept. 26 in the journal Applied Physics Letters and was presented in August at the SPIE Optics + Photonics conference in San Diego.

Terahertz radiation (wavelength range of 30 300 microns) can be used to see through paper, clothing, cardboard, plastic, and many other materials, without any of the health risks posed by current x-ray based techniques. This property has become extremely valuable for security screening, as it is safe to use on people and can detect metals and ceramics that might be used as weapons.

In addition, a scanning terahertz source can identify many types of biological or chemical compounds due to their characteristic absorption spectra in this wavelength range. Sensitivity to water content can also be utilized to study agricultural quality. Finally, through mixing with a compact coherent terahertz source, very weak terahertz signals from deep space can be detected, which may help scientists understand the formation of the universe.

Coherent terahertz radiation has historically been very difficult to generate, and the search for an easy-to-use, compact source continues today. Current terahertz sources are large, multi-component systems that may require complex vacuum electronics, external pump lasers, and/or cryogenic cooling. A single component solution without any of these limitations is highly desirable to enable next generation terahertz systems.

One possible avenue toward this goal is to create and mix two mid-infrared laser beams within a single semiconductor chip in the presence of a giant nonlinearity. This nonlinearity allows for new terahertz photons to be created within the same chip with an energy equal to the difference of the mid-infrared lasers' energies. As mid-infrared lasers based on quantum cascade laser technology are operable at room temperature, the terahertz emission can also be demonstrated at room temperature.

Razeghi and her group at the Center for Quantum Devices have taken this basic approach a step further by addressing two key issues that have limited the usefulness of initial demonstrations. Razeghi's group currently leads the world in high-power quantum cascade laser technology; by increasing the power and beam quality of the mid-infrared pumps, the terahertz power has been significantly increased by more than a factor of 30 to ~10 microwatts.

Additionally, the researchers have incorporated a novel dual-wavelength diffraction grating within the laser cavity to create single mode (narrow spectrum) mid-infrared sources, which in turn has led to very narrow linewidth terahertz emission near 4 terahertz. Further, due to the novel generation mechanism, the terahertz spectrum is extremely stable with respect to current and/or temperature. This could make it valuable as a local oscillator, which can be used for low light level receivers like those needed for astronomical applications.

Razeghi said her group will continue in hopes of reaching higher power levels.

"Our goal is to reach milliwatt power levels and incorporate tuning within the device," Razeghi said. "Theory says that it is possible, and we have all of the tools necessary to realize this potential."


'/>"/>

Contact: Megan Fellman
fellman@northwestern.edu
847-491-3115
Northwestern University
Source:Eurekalert

Related biology news :

1. Researchers: Apply public trust doctrine to rescue wildlife from politics
2. Dead Sea researchers discover freshwater springs and numerous micro-organisms
3. Eating balanced meals, farm-fresh produce benefits families, communities, nutrition researchers say
4. LSU researchers find impact of oil spill in marsh fish species
5. MU researchers find new insight into fatal spinal disease
6. UCLA Engineering researchers help develop complete map of mouse genetic variation
7. Researchers develop optimal algorithm for determining focus error in eyes and cameras
8. Researchers at Cruces Hospital describe new syndrome of slight family intellectual disability
9. UCLA researchers develop system that finds prostate cancer spread earlier than conventional imaging
10. Joslin researchers identify pathways leading to activation of good fat
11. Kansas researchers find enriched infant formulas benefit brain and heart
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/11/2017)... , April 11, 2017 Crossmatch®, a ... authentication solutions, today announced that it has been ... Research Projects Activity (IARPA) to develop next-generation Presentation ... "Innovation has been a driving force ... program will allow us to innovate and develop ...
(Date:4/6/2017)... April 6, 2017 Forecasts by ... Document Readers, by End-Use (Transportation & Logistics, Government & ... Gas & Fossil Generation Facility, Nuclear Power), Industrial, Retail, ... Are you looking for a definitive report ... ...
(Date:4/4/2017)... NEW YORK , April 4, 2017   ... solutions, today announced that the United States Patent and ... The patent broadly covers the linking of an iris ... the same transaction) and represents the company,s 45 th ... our latest patent is very timely given the multi-modal ...
Breaking Biology News(10 mins):
(Date:8/18/2017)... ... August 18, 2017 , ... ... for the Semiconductor, MEMS, and Microfluidics Industries, announces the new Model 800E front ... more often in automated production mask aligners. OAI has already received and ...
(Date:8/16/2017)... ... August 16, 2017 , ... Tunnell Consulting announced today that ... ISPE Annual Meeting and Expo , to be held October 29 through November ... is “Driving innovation to advance patient therapies.” , The ISPE Annual Meeting and Expo ...
(Date:8/16/2017)... Philadelphia, PA (PRWEB) , ... August 16, 2017 , ... ... thought, they are much more closely connected than one might think. A Mesh ... Grizzly, will open at the University City Science Center’s Esther Klein Gallery (EKG) on ...
(Date:8/16/2017)... Mass. , Aug. 16, 2017  This year,s edition of the ... leader in life sciences workforce solutions, has made the list for the ... 5000 recognizes the nation,s fastest-growing private companies based on a set of ... 50, which includes the fastest-growing companies in the Bay State ... Inc. 5000 ...
Breaking Biology Technology: