Z-Scan Technique - Measurement of Third Order Non-linear Optical Properties of Ammonium Penta Borate Single Crystals

Single crystals of Ammonium Penta Borate of dimensions 1.1 x 0.7 x 1.3 cm3 were grown using de-ionized water as a solvent by slow evaporation solution growth method and subjected to optical characterization. Good optical quality of crystal was observed and the grown crystals were characterized by single crystal X-ray diffraction study which confirms that the grown crystal belongs to P21/c space group. The UV-Vis-NIR spectra of Ammonium Penta Borate clearly indicate the absence of absorption in the visible region. Absence of SHG (.( 2) = 0), affirms that this crystal is of Centro- symmetric class and hence the Z- scan technique is employed for THG. Through the Z- scan technique, the nonlinear refractive index n2 and the absolute value of the third order non- linear optical susceptibility.( 3) have been measured at the wavelength of 632.8nm and were found to be 1.7234 x 10- 7 cm2/ W and 6.7623 x 10- 7 esu respectively. Also, at the same wavelength, the real.R ( 3) and imaginary.I ( 3) parts of.( 3) have been calculated as 6.7538 x 10- 7 esu and 3.4025 x 10- 8 esu respectively. Ammonium Penta Borate exhibits saturation absorption and self- defocusing performance and its non- linear absorption co- efficient a is determined as 9.2286 x 10- 4 cm / W.