Tunable Infrared Quantum Cascade Lasers for Active Electro-Optical Remote Sensing

Remote sensing of airborne chemicals from industrial or illicit emissions is greatly facilitated by looking for characteristic absorption patterns of mid-infrared (IR) light with wavelengths from 3 to 14 µm. The DOE can use this type of remote sensing to monitor and detect effluents from nuclear fuel cycle processes, for example. At present, there is no robust and reliable way to generate an intense beam of mid-IR light that can be tuned in wavelength to look for these absorptions. In this project, a high power, tunable, mid-IR laser will be designed and built for use in remote sensing applications. State-of-the-art quantum cascade laser (QCL) technology will be incorporated in a miniaturized, tunable laser cavity to provide a field-ready, mid-IR light source to enable detection of airborne chemicals. Phase I developed materials suitable for incorporation in a miniaturized tunable laser cavity. Tunable near-IR diode laser technologies were extended to the mid-IR to enable design and construction of a miniaturized, tunable, mid-IR laser platform. Several prototypes were built, which demonstrated pulsed tunable mid-IR lasers. In Phase II, the platform technology will be extended to achieve the continuous wave (CW) lasers that are necessary for remote sensing. The laser cavity design and quantum cascade (QC) device coatings will be optimized to allow continuous tuning of the CW lasers. CW QC devices, throughout the entire mid-IR, will be designed and developed. Commercial Applications and Other Benefits as described by the awardee: Tunable, mid-IR lasers should find commercial applications related to the remote sensing of industrial emissions, stand-off detection of illicit chemicals, and medical breath diagnostics. In addition, tunable mid-IR lasers should allow new applications in diagnostic imaging to be developed, both for medical and industrial purposes. At present, no practical technologies are available that allow the creation of tunable IR light for commercial applications.