Nonlinear optical materials are important in the fields of optical information process, communication and integrated optics. Materials of large nonlinear optical properties are required for those applications and it is necessary to have macroscopic non-centrosymmetric structure for utilizing the second order properties. Much attention has been paid to organic materials because of their large nonlinear optical effects due to their unique delocalized π-electron distributions. MNA and MBANP crystals possess large optical nonlinearity, and both are monoclinic and optically biaxial.
In this study, MNA crystals were grown by solvent evaporation method to obtain single crystals of about 10×1㎣ and by temperature lowering method to get crystals of about 5×5×1㎣. Refractive indices at λ=0.780㎛ were measured to be $n_{x}$=2.56, $n_{z}$=1.44.
Second harmonic generation(SHG) of MNA crystal was measured and it was shown that phase matched SHG from the light incident through y-cut is not possible at λ=1.064㎛ Walkoff angle at (Θ, Φ)=(90°, 30.8°) is 7.1° while it has the largest value of 9.8° at (Θ, Φ)=(55.7°, 49°). Full width at half maximum(FWHM)'s of mismatch coefficient were 7.0° for △Θ and 0.63° for △φ.
The second order nonlinear coefficient $d_{33}$ of MNA was measured by Maker fringe technique using a quartz as a reference and the measured value is ~1pm/V. Nonlinear coefficients of MBANP are $d_{11}~0pm/V$ and $d_{22}$=6.9pm/V. Second harmonic generation efficiency of MBANP when phase matched at (Θ, Φ)=(73°, 90°) is 6% at wavelength λ=1.064㎛.
