Proceedings Article | 25 September 2007
Patrick McCann, Khosrow Namjou, Chad Roller, Gina McMillen, Pratyuma Kamat
KEYWORDS: Mid-IR, Quantum cascade lasers, Laser applications, Semiconductor lasers, Laser development, Molecules, Sensors, Cancer, Gas lasers, Group IV-VI semiconductors
A promising absorption spectroscopy application for mid-IR lasers is exhaled breath analysis where sensitive,
selective, and speedy measurement of small gas phase biomarker molecules can be used to diagnose disease and monitor
therapies. Many molecules such as nitric oxide, ethane, formaldehyde, acetaldehyde, acetone, carbonyl sulfide, and
carbon disulfide have been connected to diseases or conditions such as asthma, oxidative stress, breast cancer, lung
cancer, diabetes, organ transplant rejection, and schizophrenia. Measuring these and other, yet to be discovered,
biomarker molecules in exhaled breath with mid-IR lasers offers great potential for improving health care since such
tests are non-invasive, real-time, and do not require expensive consumables or chemical reagents. Motivated by these
potential benefits, mid-IR laser spectrometers equipped with presently available cryogenically-cooled IV-VI lasers
mounted in compact Stirling coolers have been developed for clinical research applications. This paper will begin with a
description of the development of mid-IR laser instruments and their use in the largest known exhaled breath clinical
study ever performed. It will then shift to a description of recent work on the development of new IV-VI semiconductor
quantum well materials and laser fabrication methods that offer the promise of low power consumption (i.e. efficient)
continuous wave emission at room temperature. Taken together, the demonstration of compelling clinical applications
with large market opportunities and the clear identification of a viable pathway to develop low cost mid-IR laser
instrumentation can create a renewed focus for future research and development efforts within the mid-IR materials and
devices area.
