Linear- and nonlinear-optical properties of 2-cyclooctylamino-5-nitropyridine

The linear- and nonlinear-optical properties of 2-cyclooctylamino-5-nitropyridine (COANP) have been investigated. The refractive indices exhibit strong dispersion and a high birefringence (0.15–0.3) in the visible. The three main refractive indices at λ = 550 nm are na = 1.700, nb = 1.845, and nc = 1.683. The calculations that were carried out show interesting critical (frequency doubling of the Nd:YAG laser at λ = 1064 nm) and noncritical [sum-frequency generation using 488-nm (argon) and 647-nm (krypton)] phase-matching properties. The nonlinear-optical susceptibilities d32 = (32 ± 16) pm/V and d33 = (13.7 ± 2) pm/V were determined. A one-dimensional charge-transfer model can be used to explain the anisotropy of the nonlinear-optical susceptibility tensor of COANP qualitatively.