Development of Large-Aperture Periodically Poled Magnesium Oxide-doped Lithium Niobate

Optical parametric chirped pulse amplification (OPCPA) with periodically-poled nonlinear crystals is a key technology in the development of accelerator laser systems because such systems enable broadband amplification of high-energy laser pulses over a wide range of different pulse wavelengths. To avoid optical damage and the occurrence of unwanted nonlinear optical processes in the nonlinear crystal that would otherwise occur with a high-energy pulse, the intensity of the pulse must be reduced by widening the beam and expanding the aperture of the crystal as much as possible. However, it is technically challenging to periodically pole large-aperture chips with high fidelity, and none are commercially available. AdvR, Inc., proposes an innovative approach to produce cm-scale large-aperture periodically-poled magnesium oxide- doped lithium niobate (PPMgO:LN) suitable for OPCPA and other high-power nonlinear applications. AdvRs approach is enabled by its patented submount poling technique combined with recent proprietary advances in the poling setup which results in a substantial reduction in non-poling leakage current associated with poling MgO:LN. The overall objective for this Phase I SBIR project is to demonstrate the feasibility of producing periodically-poled nonlinear frequency conversion chips that have an aperture up to 10 mm. To accomplish this objective, AdvR will modify its existing submount poling apparatus and electrodes to accommodate chips up to a 10 x10 mm. An important part of this modification will be the redesign of a heating apparatus to uniformly elevate the temperature of the chip during poling which reduces the required poling voltage and improves poling uniformity. Using the upgraded submount poling configuration, poling of chips up to a thickness of 10 mm will be tried. Poling uniformity will be documented as a function of poling voltage waveform, substrate temperature, and other factors to determine the feasibility of developing an optimal poling process in Phase II for a wide range of substrate thicknesses up to 10 mm and poling periods near 30 m. Commercial Applications and Other Benefits: The development and commercialization of cm- scale periodically poled chips will greatly increase the power-handling capabilities of late-stage OPCPA and frequency conversion systems and thus enable the development of next-generation high-power, short-pulsed lasers for accelerator-based applications. Other commercial applications that will benefit from the development a high yield, low cost process for producing large aperture PPMgO:LN include laser based remote sensing, precision spectroscopy, laser machining, and infrared countermeasures.