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*STTR
Project: Broadly Tunable Quantum
Cascade Laser Technology for Remote Sensing—Aerodyne Research, Inc., 45 Manning Road, Billerica, MA 01821-3976; 978-663-9500; www.aerodyne.com
Dr. John Barry McManus, Principal,
Investigator, mcmanus@aerodyne.com
Mr. George N. Wittreich, Business Official, gnw@aerodyne.com
DOE Grant No. DE-FG02-06ER86264
Amount: $749,700
Research Institution
The mid-infrared spectral region is ideal for measuring
numerous airborne gases with high sensitivity, because many gaseous chemicals have
their strongest absorption features in this region, and atmospheric
transmission windows are present. In
order to measure different chemicals at significantly different wavelengths, a
widely tunable laser is needed. Although
a new type of mid-infrared laser, the quantum cascade laser, is currently
available at selected wavelengths, it cannot be widely tuned. This project will develop an improved,
mid-infrared, quantum-cascade-laser-based light source for spectroscopic remote
sensing, along with associated optics and software. The laser source will have increased tuning
range, tuning speed, and output power, realized by an external cavity laser
configuration with a quantum cascade gain medium. The laser design will allow compensation for
the effects of modest quality antireflection coatings, and will achieve wide
and continuous tuning of the emission wavelength. Phase I developed and demonstrated the laser
tuning technology at two different infrared wavelengths, exceeding the goals
for tuning range (up to 155 wave numbers) and continuous output power (50 milliwatts). Remote
sensing optics and instrumentation approaches were tested with a narrowly
tunable quantum cascade laser, and gas concentrations were measured over a
range path length greater than 280 meters.
In Phase II, control techniques will continue to be developed, in order
to produce a more compact and rugged laser source with wider and faster tuning,
and higher power. Optics and software
will be developed to interface to the new laser source, resulting in a
prototype instrument that will be field tested.
Commercial Applications and other
benefits as described by the awardee: The new
source should find wide utility for remote sensing and chemical sensing in the military,
industrial, and research sectors. The
ability to widely tune the laser will allow for the measurement of multiple
molecules or the wide absorption spectra of complex molecules. Many gases of interest have broad spectra
that cannot be measured with a conventional, narrowly tunable laser.