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

摘要

Single crystals of Ammonium Penta Borate of dimensions 1.1 x 0.7 x 1.3 cm~3 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 P2_1 / 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 (x~((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 opitical susceptibility χ(3) have been measured at the wavelength of 632.8nm and were found to be 1.7234 × 10~(-7)cm~2/ Wand 6.7623 × 10~(-7) esu respectively. Also, at the same wavelength, the real χ_R(3) and imaginary χ~((3)) parts of χ~((3)) have been calculated as 6.7538 x 10~(-7) esu and 3.4025 × 10~(-8) esu respectively. Ammonium Penta Borate exhibits saturation absorption and self-defocusing performance and its non-linear absorption co-efficient β is determined as 9.2286×10~(-4)cm/W.