Third Order Non-linear Optical Properties of Potassium Aluminium Sulphate Single Crystals by Z-scan Technique

Potassium aluminum sulphate dodeca hydrate crystals were grown from aqueous solution and studied by X-ray diffraction. The UV-Visual IR transmission spectra indicate a better transparency between 200 and 800 nm. The nonlinear refractive index n₂ and susceptibility χ⁽³⁾ have been measured through the Z-scan technique. The results indicate that the compound exhibits saturation absorption and self-focusing performance. Non-linear absorption Co-efficient β is determined as 7.6746 x 10 ^-4 cm/W. Non-linear refractive index n₂ measured at the wavelength of 632.8 nm is calculated as 1.46412 x 10^-8 cm²/W. The real and imaginary pars of χ⁽³⁾ have been measured at 632.8 nm and found to be 7.84088 x 10^-07 esu and 2.07218 x 10^-08 esu, respectively. The measured 3rd order non-linear properties confirm its suitability for nonlinear optical devices such as optical limiting and switching.