SBIR Phase I: Low Cost High Quality Nonlinear Optical Crystals for Laser Light Sources for Miniature Projectors

This Small Business Innovation Research (SBIR) Phase I project will demonstrate the feasibility of growing high-quality fibers of periodically poled Mg-doped LiNbO3 for visible light generation, by a modified version of the laser heated pedestal growth (LHPG) method. Other methods used to grow these crystals have proven to be very expensive and to lead to unreliable results with a very long cycle time, making the use of nonlinear crystals non viable for many applications. Periodically poled crystals poled with the conventional LHPG method exhibit curved ferroelectric domains, which results in a loss of nonlinear optical conversion efficiency, making the technology unpractical for miniature display applications where maximum brightness is required. The company will commercialize LHPG-grown frequency doubling crystals of periodically poled Mg-doped LiNbO3 with higher quality, lower price, faster delivery, and longer lifetimes than the Czochralski-grown crystals available today. In order to accomplish this, the technical approach will be to create and engineer a novel optical after heater which can generate high enough temperatures to enable LHPG to grow high quality thicker fibers, with straight ferroelectric domains thus enabling high nonlinear optical conversion efficiency at 532nm in a very reliable and reproducible way. If successful the proposed LHPG method will produce single-crystal fibers of many compounds with low defect density and low internal strain. Its main limitation had been the inability to grow fibers with diameters larger than 0.8 to 1.2 millimeters and also with straight domains for periodically poled crystals, limiting the optical efficiency of the devices. The team will demonstrate a novel technique for growing LHPG fibers with bigger diameters and ferroelectric domains exhibiting no curvature. This work will enable high-volume manufacturing of frequency doubling chips by LHPG and thereby facilitate the commercialization of miniature projectors (especially the ones to be embedded in cell phones or other handheld devices) and other consumer electronics devices, which will rely on frequency-doubled lasers. The project will contribute to the theory of crystal growth. It will help materials scientists in research institutions to make further discoveries because thicker fibers are easier to study. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).