SBIR Phase I: Large Aperture, Periodically Poled, Hydrothermal Potassium Titanyl Phosphate for Highly Efficient Frequency Conversion of High-Power Solid-State and Fiber Lasers.

This Small Business Innovation Research (SBIR) Phase I project proposes to investigate the feasibility of fabricating large-aperture, periodic ferroelectric domain gratings for quasi-phase matched laser frequency conversion. The key innovation in this effort is the use of low temperature hydrothermally grown potassium titanyl phosphate (LTH-KTP) as the nonlinear optical substrate material. Using LTH-KTP will enable a simplified poling process, resulting in increased fabrication yields, lower component costs as well as allow the fabrication of high-quality, large aperture (>2mm) periodically poled wafers. The ability to periodically pole thick wafers of hydrothermally grown KTP, combined with its high resistance to optical damage (>500MW/cm2) will enable highly efficient, wavelength conversion of high-power laser sources for use in Lidar-based remote sensing applications including the increasingly important Homeland Security area of standoff detection of chemical and biological agents. The anticipated results of the Phase I effort include a demonstration of periodic poling in LTH-KTP using the micro-electrode technology and a preliminary assessment of the effect different poling configurations have on the quality of the domain grating. In the Phase II effort, the poling technology will be refined and grating structures suitable commercial applications will be fabricated. The ability to periodically pole thick wafers of hydrothermally grown KTP, combined with its high resistance to optical damage will enable highly efficient, nonlinear optical frequency conversion of high-power ytterbium fiber and diode pumped solid state Nd: YAG lasers sources. Laser sources with increased pulse energies, wavelength flexibility, and excellent beam quality, will find use in both civilian and military applications. Specific applications include laser-based material processing (cutting, welding and marking), remote sensing for standoff detection of chemical and biological agents, environmental monitoring, forest management as well as Lidar-based missile identification, tracking, and targeting.