High spectroscopic quality, compact, robust, semiconductor-based tunable laser sources across the mid-IR, 3 - 12 Pm, would dramatically enhance the capabilities of active point and remote sensors Recent progress in semiconductor materials and lasers offers opportunities for continuously tunable, high spectral purity, high-power sources covering the entire IR molecular fingerprint region including the critical 3-5 Pm and 8-12 Pm atmospheric windows. Optically pumped, high-power semiconductor laser sources, have recently been developed across the IR. These applications typically demand high beam quality, "power-in-a-bucket" performance with only coarse wavelength control. In contrast, spectroscopic applications put a premium on spectral quality and agility with less emphasis on broadband power. The primary objectives of this program are to develop the integrated spectral control technologies necessary for robust and agile spectroscopic use of these sources and to demonstrate their utility for sensors.
In a collaboration between UNM and AFRL, the Air Force Research Laboratory, preliminary work has demonstrated that the linewidth of lasers can be dramatically reduced by the use of a distributed feedback (DFB) grating structure. In this research, variations in the design and in the parameters of this structure will be investigated with emphases on narrow linewidth, high-power operation, and continuous, single-frequency tuning over a large wavelength range. For optically pumped devices, additional degrees of freedom are available since the gain stripe is defined by the optical configuration and is totally flexible. A transversely chirped grating can be used to provide for continuous tuning. This is a totally new concept for the tuning of semiconductor lasers and forms the basis of the planned investigation. Based on the demonstrated gain-bandwidth of this laser system, continuous tuning ranges of several hundreds of cm -1 are anticipated - far in excess of that available by any other technique.
This program will support one student and one postdoctoral researcher. UNM is a Hispanic ServingInstitution with large populations of Hispanic and Native American students. The PI already has strong interactions with recruiting efforts in the Native American community.
