Navigation Links
Researchers realize high-power, narrowband terahertz source at room temperature
Date:12/12/2011

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 technology :

1. Understanding the science of solar-based energy: more researchers are better than one
2. Researchers decode viral process that prepares cells for HIV infection
3. Dartmouth researchers advance cellulosic ethanol production
4. Researchers develop new model for cystic fibrosis
5. Use it or lose it? Researchers investigate the dispensability of our DNA
6. Sigma-Aldrich and the University of Illinois Offer New Boronic Acid Surrogates to Researchers Worldwide Through Licensing Agreement
7. Researchers write protein nanoarrays using a fountain pen and electric fields
8. Researchers show how to stamp nanodevices with rubber molds
9. The Lancets New Online Medical Journal Helps Clinicians and Medical Researchers Find Practice-Changing Evidence Quickly and Easily
10. Ultrafast lasers give CU-Boulder researchers a snapshot of electrons in action
11. VAP(R) Cholesterol Test Helps Researchers Identify Treatment Effects of Combination Therapy
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/23/2016)... ... , ... The need for blood donations in South Texas and across the nation is growing. ... Tissue Center, blood donations are on the decline. In fact, donations across the country are ... in South Texas in the last four years alone. , There is no substitute for ...
(Date:5/23/2016)... , May 23, 2016 Oxitec CEO ... th at 10:15 a.m. ET before the United States ... genetically engineered mosquitos can play in controlling the spread of ... the Zika virus.      (Logo: http://photos.prnewswire.com/prnh/20150630/227348 ... mosquito with a self-limiting gene. Trials in Brazil ...
(Date:5/23/2016)... ... 23, 2016 , ... Foresight Institute , a leading ... for the 2015 Foresight Institute Feynman Prizes. , These prestigious prizes, named ... for experiment and the other for theory in nanotechnology. Prof. Markus J. Buehler, ...
(Date:5/20/2016)... ... 20, 2016 , ... Kablooe Design, a leading provider of product design and ... anniversary of the business. “We have worked hard to build long-term relationships,” says President ... privilege and honor of serving their product design and development needs through the years.” ...
Breaking Biology Technology:
(Date:3/15/2016)... York , March 15, 2016 ... market report published by Transparency Market Research "Digital Door Lock ... and Forecast 2015 - 2023," the global digital door lock ... 731.9 Mn in 2014 and is forecast to grow at ... Growth of micro, small and medium enterprises (MSMEs) across the ...
(Date:3/11/2016)... http://www.apimages.com ) - --> http://www.apimages.com ) - ... ( http://www.apimages.com ) - Germany . The ... refugee identity cards. DERMALOG will be unveiling this device, and a ... next week.   --> Germany . ... new refugee identity cards. DERMALOG will be unveiling this device, and ...
(Date:3/9/2016)... YORK , March 9, 2016 This ... and future states of the RNA Sequencing (RNA Seq) ... segments such as instruments, tools and reagents, data analysis, ... Analyze various segments of the RNA-Sequencing market such as ... services Identify the main factors affecting each segment and ...
Breaking Biology News(10 mins):