Nonlinear optics with lithium niobate nanocrystals

Lithium niobate (LiNbO 3 ) is a frequently used material for nonlinear optics, due to its large nonlinear coefficent and high transparency over a large wavelength range. Domain engineering is needed to achieve quasi-phase matching which is necessary to address a wide wavelength range.[1] The domain engineered bulk crystals certainly yield the highest effective nonlinear coefficients, but the design of domain structures is limited due to the crystalline structure of the material and its non-trivial mechanical processing. A promising idea to gain more flexibility is to use LiNbO 3 -hybride materials, for example the combination with polymers. For that, it is critical to produce small LiNbO 3 nanocrystals to minimize scattering losses and to disperse them homogenously in a host material. We modified a double-alkoxide sol-gel bottom-up synthesis route to produce LiNbO 3 -nanocrystals with a mean diameter of about 40 nm with the possibility of doping the crystals.[2]