Third-order nonlinear optical properties of ADP crystal

Abstract

By using the Z-scan method, we investigated the third-order nonlinear optical (NLO) properties of ADP crystal at different wavelengths (355, 532, and 1064 nm) and different orientations ([001], [100], [110], I and II). The experimental data were fitted by NLO theory, to give out the two photon absorption (TPA) coefficient β2 and the nonlinear refractive index n2. When the light source changed from a 40 ps, 1064 nm fundamental laser to a 30 ps, 355 nm third-harmonic-generation (THG) laser, the β2 value increased about 5 times (0.2 × 10−2 → 1 × 10−2 cm GW−1), and the n2 value increased about 1.5 times (1.5 × 10−16 → 2.2 × 10−16 cm2 W−1). Among all of the orientations, the [110] sample exhibits the smallest β2, and the second smallest n2. It indicates that this orientation and its surroundings will be the preferred directions for high-power laser applications of ADP crystal.