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

本小型企业创新研究（SBIR）第一期项目旨在研究制造大孔径、周期铁电畴光栅用于准相位匹配激光变频的可行性。这项工作的关键创新是使用低温水热生长的磷酸钛基钾（LTH-KTP）作为非线性光学衬底材料。使用LTH-KTP将简化极化过程，从而提高制造产量，降低组件成本，并允许制造高质量的大孔径（2mm）周期性极化晶圆。水热生长的KTP周期性极厚晶圆的能力，加上其对光学损伤的高抗性（500MW/cm2），将使高功率激光源的高效波长转换用于基于激光雷达的遥感应用，包括日益重要的国土安全领域的化学和生物制剂的检测。第一阶段工作的预期结果包括使用微电极技术在LTH-KTP中进行周期性极化的演示，以及对不同极化配置对畴光栅质量的影响的初步评估。在第二阶段的努力中，极化技术将得到改进，适合商业应用的光栅结构将被制造出来。水热生长的KTP周期性极厚晶圆的能力，加上其对光学损伤的高抵抗能力，将使高功率镱光纤和二极管泵浦固体Nd: YAG激光源的高效、非线性光频率转换成为可能。激光源增加脉冲能量，波长的灵活性，和优良的光束质量，将在民用和军事应用中找到用途。具体应用包括基于激光的材料加工（切割、焊接和打标）、用于化学和生物制剂对峙探测的遥感、环境监测、森林管理以及基于激光雷达的导弹识别、跟踪和瞄准。

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.