DARPA selects Pranalytica as one of three to continue development of high-efficiency mid-IR QCLs

June 30, 2009--The US's Defense Advanced Research Projects Agency (DARPA) has selected Pranalytica Inc. (Santa Monica, CA) to continue in the Efficient Mid Infrared Laser (EMIL) program, a project created to fill the Department of Defense's need for directional infrared countermeasures (DIRCM), advanced stand-off chemical sensors, and laser radar (LADAR). EMIL's Phase 1B aims for 50% wall plug efficiency for high-efficiency quantum cascade lasers (QCLs).

Jun 30th, 2009

June 30, 2009--The US's Defense Advanced Research Projects Agency (DARPA) has selected Pranalytica, Inc. (Santa Monica, CA) to continue its involvement in the Efficient Mid Infrared Laser (EMIL) program, a project created to fill the Department of Defense's (DoD's) need for directional infrared countermeasures (DIRCM), advanced stand-off chemical sensors, and laser radar (LADAR).

"The applications of high power quantum cascade lasers (QCLs), including DIRCM, help produce a safer and more secure environment for our nation's war fighters. Furthermore, the numerous civilian applications enabled by these lasers will help making our world safer, cleaner, and more connected," said Dr. C. Kumar N. Patel, president and CEO of Pranalytica. Potential non-military applications include DIRCM protection of civilian airliners from shoulder-fired missiles, detection of toxic industrial gases, atmospheric pollution monitoring and free-space optical communications.

The goal of Phase 1B of the EMIL program is to reach a wall plug efficiency (WPE) of 50% for QCLs operating at 4.6 µm and producing a minimum of one watt of continuous wave power at room temperature. Of the six institutions awarded participation in Phase 1 of the EMIL program, only three were selected to work on Phase 1B.

At the start of the EMIL program, quantum cascade lasers operating in the 4.6 µm spectral region typically provided only a few hundred mW of continuous wave (CW) power at room temperature (RT) with WPE of under 4 percent. During Phase 1 of the program, Pranalytica succeeded in demonstrating QCLs with CW/RT power exceeding 3 watts and a WPE of over 13 percent. Achieving high WPE is very important for almost all system level applications that demand high laser power. Without high WPE, the use of such lasers in system application would require higher electrical power input to the laser source for the same laser output, and also would significantly exacerbate the problem of removal of waste heat (input energy that was not converted into useful laser power).

"Pranalytica's success in increasing the CW/RT laser power by over an order of magnitude, and WPE by a factor of over three from the start of the EMIL program has depended on a systematic approach to the improvements of all aspects of QCL performance," noted Patel. "This approach enabled the Pranalytica team to accomplish several simultaneous advances in various areas of QCL design, fabrication, and thermal management. First, the Pranalytica team invented a radically new design of QCL gain structure and succeeded in removing the optimization-limiting resonance condition at the heart of traditional QCL designs, while at the same time maintaining efficient carrier dynamics. This new design freedom allows us to better unlock the potential of novel, high performance QCL designs."

In order to both improve WPE and produce useful, single-ended output lasers, Pranalytica has succeeded in developing high performance high reflectance (HR) laser facet coatings. Optical power density at the facets of high power QCLs can reach tens of megawatts per square centimeter – a remarkably high value made even more formidable by the fact that coatings are deposited directly onto the active medium of QCLs. Pranalytica has overcome significant obstacles related to materials and deposition technology of such coatings for MWIR wavelengths, demonstrating reliable operation of 2W QCLs over hundreds of hours. This achievement enabled Pranalytica to offer its turn-key CW/RT QCL systems as a standard product at the 2W output power level.

In the area of QCL thermal management, Pranalytica has adapted its proven, industrial-quality packaging solutions, enabling sustainable high power operation of leading-edge QCLs in CW regime at room temperature with only simple air cooling.

"These advances position Pranalytica very well for successful performance under Phase 1B of the DARPA EMIL program," commented Patel. "They also pave the way for commercial acceptance of very high power QCL systems that is already happening today."

Pranalytica calls itself the world's only supplier of complete, fully packaged, turn-key high power QCL systems.

For details on DARPA's EMIL, see the program website. For more information on Pranalytica visit the company's website.

Posted by Barbara G. Goode, barbarag@pennwell.com, for Laser Focus World.

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