Growth and characterization of diphenylmethanol single crystal by vertical Bridgman technique for second and third order nonlinear optical applications

An organic nonlinear optical diphenylmethanol single crystal was grown by vertical Bridgman technique using single wall ampoule. The lattice parameters and crystal system of grown crystal were confirmed by single crystal XRD analysis. The functional groups present in the crystal were identified by FTIR analysis. The thermal properties of the grown crystal were studied by thermo-gravimetric and differential thermal analyses. UV-vis-NIR spectroscopic analysis shows that the crystal has low cut-off wavelength at 271 nm and band gap value of 4.43 eV. The fluorescence spectrum indicates that the crystal exhibits emission at 289 nm wavelength in UV region. The second harmonic generation efficiency of diphenylmethanol was determined by Kurtz and Perry powder technique. The third order nonlinear optical parameters like nonlinear refractive index (n(2)), nonlinear absorption coefficient (beta) and third order nonlinear susceptibility (chi(3)) of the crystal were determined by Z-scan technique using cw Nd:YAG laser light of wavelength 532 nm. The self-defocusing and saturation absorption nature of the crystal were identified from Z-scan closed and open aperture methods respectively. The crystal exhibits good power limiting behaviour due to non linear refraction. The laser damage threshold study indicates that the crystal has no surface damage upto 29.5 mJ.