Navigation Links
Engineers demonstrate first room-temperature semiconductor source of coherent Terahertz radiation

Cambridge, Mass. -- May 19, 2008 -- Engineers and applied physicists from Harvard University have demonstrated the first room-temperature electrically-pumped semiconductor source of coherent Terahertz (THz) radiation, also known as T-rays. The breakthrough in laser technology, based upon commercially available nanotechnology, has the potential to become a standard Terahertz source to support applications ranging from security screening to chemical sensing.

Spearheaded by research associate Mikhail Belkin and Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, both of Harvard's School of Engineering and Applied Sciences (SEAS), the findings will be published in the May 19 issue of Applied Physics Letters. The researchers have also filed for U.S. patents covering the novel device.

Using lasers in the Terahertz spectral range, which covers wavelengths from 30 to 300å, has long presented a major hurdle to engineers. In particular, making electrically pumped room-temperature and thermoelectrically-cooled Terahertz semiconductor lasers has been a major challenge. These devices require cryogenic cooling, greatly limiting their use in everyday applications.

"By contrast, our device emits T-rays with several hundreds of nanowatts of power at room temperature and microwatts of power at temperatures easily achievable with commercially available thermoelectric coolers," says Belkin. "Further, there is the potential of increasing the terahertz output power to milliwatt levels by optimizing the semiconductor nanostructure of the active region and by improving the extraction efficiency of the terahertz radiation."

To achieve the breakthrough and overcome the temperature limitations of current laser designs, the researchers engineered a room temperature mid-infrared Quantum Cascade Laser (QCL) that emits light at two frequencies simultaneously. The generation of Terahertz radiation occurs via the process of difference-frequency generation inside the laser material at room temperature at a frequency of 5 THz (equal to the difference of the two mid-infrared QCL frequencies).

Mid-infrared QCLs were invented and demonstrated by Capasso and his team at Bell Labs in 1994. The compact millimeter length semiconductor lasers operate routinely at room temperature with high optical powers and are increasingly used in the commercial sector for wide range of applications in chemical sensing and trace gas analysis. The devices, made by stacking ultra-thin atomic layers of semiconductor materials on top of each other, are variable and tunable, allowing an engineer to adjust the energy levels in the structure to create artificial laser medium.

"Terahertz imaging and sensing is a very promising but relatively new technology that requires compact, portable and tunable sources to achieve widespread penetration. Our devices are an important first step in this direction," said Capasso. "We believe our THz source has great development potential because the nanoscale material used was grown by Molecular Beam Epitaxy, a commercial and widely used thin film growth technique which 'spray paints' atoms on a surface one layer at a time."

The ability of Terahertz rays to penetrate efficiently through paper, clothing, cardboard, plastic and many other materials makes them ideal for use in many applications. For example, a device emitting T-rays could be used to image concealed weapons, detect chemical and biological agents through sealed packages, see tumors without causing any harmful side effects, and spot defects within materials such as cracks in the Space Shuttle's foam insulation.


Contact: Michael Patrick Rutter
Harvard University

Related biology technology :

1. Penn engineers design computer memory in nanoscale form that retrieves data 1,000 times faster
2. Penn engineers design computer memory in nanoscale form that retrieves data 1,000 times faster
3. Harvard University engineers demonstrate quantum cascade laser nanoantenna
4. Cardiff University engineers give industry a moths eye view
5. Surface dislocation nucleation: Strength is but skin deep at the nanoscale, Penn engineers discover
6. Engineers make first active matrix display using nanowires
7. Engineers harness cell phone technology for use in medical imaging
8. Nanowires may boost solar cell efficiency, UC San Diego engineers say
9. Elekta Demonstrates Commitment to Stereotactic Innovation at EANS
10. New Phase III Data Demonstrate Oxycodone / Naloxone Combination Tablet Reduces Opioid-Induced Bowel Dysfunction in Patients With Chronic Severe Pain
11. ChemoCentryx Demonstrates Recently Discovered Chemokine Receptor CXCR7 is Essential in Tumor Growth
Post Your Comments:
Related Image:
Engineers demonstrate first room-temperature semiconductor source of coherent Terahertz radiation
(Date:11/25/2015)... Md. , Nov. 25, 2015  PharmAthene, Inc. ... Directors has adopted a stockholder rights plan (Rights Plan) ... net operating loss carryforwards (NOLs) under Section 382 of ... --> PharmAthene,s use of its NOLs ... "ownership change" as defined in Section 382 of the ...
(Date:11/25/2015)... and HOLLISTON, Mass. , Nov. ... (Nasdaq: HART ), a biotechnology company developing bioengineered ... Jim McGorry will present at the LD ... 2015 at 2:30 p.m. PT. The presentation will be ... 30 days. Management will also be available at the ...
(Date:11/25/2015)... (PRWEB) , ... November 25, 2015 , ... ... and the Organization of Black Aerospace Professionals (OPBAP) has been formalized with the ... other AMA team leaders met with OPBAP leaders Capt. Karl Minter and Capt. ...
(Date:11/25/2015)... San Francisco, CA (PRWEB) , ... November 25, ... ... leading microbial genomics company uBiome, were featured on AngelList early in their initial ... by launching an AngelList syndicate for individuals looking to make early stage investments ...
Breaking Biology Technology:
(Date:10/27/2015)... BERLIN, Germany , October 27, 2015 ... 2015. SMI,s Automated Semantic Gaze Mapping technology (ASGM) automatically ... SMI,s Eye Tracking Glasses , so that ... Suite BeGaze. --> Munich, Germany ... technology (ASGM) automatically maps data from mobile eye tracking ...
(Date:10/26/2015)... ALTO, Calif. and LAS VEGAS ... Nok Nok Labs , an innovator in modern ... Alliance , today announced the launch of its latest ... first unified platform enabling organizations to use standards-based authentication ... The Nok Nok S3 Authentication Suite is ideal for ...
(Date:10/23/2015)... GOLETA, California , October 23, 2015 ... Instruments (SMI) announce a mobile plug and play integration ... interactive real-world tasks SensoMotoric Instruments (SMI) ... established wearable solutions for eye tracking and physiological data ... with SMI Eye Tracking Glasses 2w and ...
Breaking Biology News(10 mins):