Study on nonlinear refractive properties of KDP and DKDP crystals

The nonlinear refractive index n 2 is an important parameter for the nonlinear optical properties of a medium. This study primarily targets to measure the third-order nonlinear optical properties of potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP) with 70% deuteration content at λ = 532 nm using the Z-scan technique. The relationship between nonlinear refraction and direction has been studied in detail. Nonlinear refractive index n 2 , γ and third-order nonlinear susceptibilities x k 3 (esu) were calculated through normalized transmittance curves and theoretical formulas. The results indicate that the nonlinear refractive indexes of KDP and DKDP are positive and possess obvious self-focusing effects in high-power laser systems. The nonlinear refractive index n 2 is an important parameter for the nonlinear optical properties of a medium. Especially for the anisotropic media, the nonlinear refractive index is closely related with the direction.