A potentially efficient, tunable laser is proposed that, can, in principle, span the 2.8 to 3.4 micron wavelength range, a technically challenging area for atmospheric constituents and coherent wind measurements. The concept is based on a BaY2F8 crystal co-doped with thulium and dysprosium. Promising recent spectroscopic and dynamic measurements indicate excellent prospects for efficient energy transfer between the Tm3+ and the Dy3+ ions, since thulium absorbs in a region accessible to standard semiconductor arrays. The proposed laser offers, for the first time, the promise of a diode pumpable, direct, tunable emission in the 3 micron spectral region. The primary goal for this Phase I project is to demonstrate lasing from Tm,Dy:BaYF crystals pumped at around 800 nm. Several crystals will be grown to determine the effect of different ion concentrations on crystal level dynamics and multiphonon relaxation processes, followed by selection of samples with the most promising compositions for laser experiments. Techniques demonstrated with existing Ho,Tm:YLF lasers will be considered to address issues of power scaling and/or narrow-band operation. In addition, a new laser material, with even lower phonon energies than BYF, Dy: NaYF4 will be evaluated. Anticipated Benefits and
Potential Commercial Applications: A tunable, efficient solid state laser source will find many applications both government and commercial. A particular government beneficiary is the countermeausre area, where applications are of interest to a number of DOD branches, especially the Army. In addition, NASA has an ongoing interest in this type of laser for coherent wind measurements and other atmospheric lidar instrumentation. A likely near-term commercial application area is laser surgery, especially for ophthalmology (e.g., refractive surgery), dentistry and dermatology (e.g., laser skin resurfacing). Further potential applications may be found in the areas of medical diagnostics, metrology, inspection, and instrumentation for various scienific and spectroscopic studies (especially the O-H bond)
