Novel electro-optic molecular cocrystals with ideal chromophoric orientation and large second-order optical nonlinearities

We show, for the first time to our knowledge, that highly nonlinear optically active as well as orientationally optimized crystalline materials for second-order nonlinear optics can be prepared by a proper design of short hydrogen-bonded molecular aggregates derived from a specially developed merocyanine dye. One of the cocrystals is shown to be a very useful and highly efficient crystalline material for electro-optic devices because of the perfect chromophoric orientation, the large electro-optic coefficient r₁₁₁ = 30 ± 3 pm/V at λ = 1535 nm, and the greatly improved physical properties such as higher melting point and crystal properties such as crystallinity. In addition, we demonstrate that one can vary or tune the linear and nonlinear optical properties of this cocrystal without modifying the chromophoric orientation in the crystal lattice by changing the crystal growth conditions.