Search Menu
Photonics Media Photonics Marketplace Photonics Spectra BioPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Lasers for Standoff Sensing Improved

Facebook Twitter LinkedIn Email
EVANSTON, Ill., Aug. 27, 2012 — A new resonator design that controls both wavelength and beam quality enables the purest, brightest, and most powerful beams ever from a single-mode infrared quantum cascade laser. The work improves the accuracy of the devices, critical for boosting the standoff detection of gas, explosives, or other hazardous materials to even greater distances.

Almost all chemicals — including nerve gases and toxic industrial materials — can be identified by infrared absorption in the 8- to 12-µm range, making the wavelength attractive for military and industrial uses. And the relative transparency of the atmosphere at these wavelengths is useful for standoff sensing.

Successful standoff sensing applications require a high-power, single-mode laser source with exceptional beam quality. Incorporating all three qualities into a single device has presented a significant challenge, and many complex structures have been proposed with limited success.

Manijeh Razeghi, the Walter P. Murphy Professor of Electrical Engineering and Computer Science at Northwestern University’s McCormick School of Engineering and Applied Sciences, and colleagues developed the resonator using a new type of distributed feedback mechanism called B-DFB, a simple diffractive feedback in an angled laser cavity.

(a) Schematic of B-DFB. (b) Scanning electron microscope image of the fabricated device. (c) Spectrum. (d) Far field.

(a) Schematic of B-DFB. (b) Scanning electron microscope image of the fabricated device. (c) Spectrum. (d) Far field. (Image: Northwestern)

Razeghi and her group demonstrated >6-W peak power with nearly diffraction-limited beam quality at a 10.4-µm wavelength — the highest-power single-mode semiconductor laser demonstrated at a wavelength greater than 10 µm. Greater output power is expected with further refinement, particularly related to optimization of the cavity design and the gain medium.

“Our resonator is the most promising device for creating high-power, single-mode laser sources with good beam quality, and it is inexpensive and can be realized at room temperature,” said Razeghi, who also leads the Center for Quantum Devices. “Furthermore, the design can be applied to a wide range of semiconductor lasers at any wavelength.”

The B-DFB development is complementary to active research efforts within the Center for Quantum Devices but is not yet directly funded.

The findings appeared Aug. 21 in Applied Physics Letters.

For more information, visit:
Aug 2012
infrared absorption
Infrared radiation absorbed by crystals as a result of the excitation of lattice vibrations in which ions having opposite charges move relative to one another. These vibrations take place in a narrow band of frequencies.
The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
10.4 micronsAmericasangled laser cavityB-DFBCenter for Quantum Deviceschemicalsdefensediffractive feedbackdistributed feedbackgood beam qualityIllinoisimagingindustrialindustrial applicationsinfrared absorptionlasersManijeh RazeghiMicroscopymilitary applicationsNorthwestern Universityphotonicspure beamsResearch & Technologysemiconductor laserssingle-mode quantum cascade laserstandoff sensingwavelength control

back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2023 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x We deliver – right to your inbox. Subscribe FREE to our newsletters.
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.