Optical properties of the vacuum-ultraviolet nonlinear optical crystal—BPO_4

Studies on the linear and nonlinear optical properties of the BPO4 crystal have been carried out experimentally. The transmittance spectra in the vacuum-ultraviolet and near-infrared spectral regions were obtained, showing a transparency in the range from 134 to 4230 nm. The refractive indices were accurately measured at 12 wavelengths from 0.2537 to 1.530 μm and the Sellmeier equations constructed. Moreover, the nonlinear optical coefficients of the BPO4 crystal were measured with the Maker fringes technique, which gave a result of d36=0.76 pm/V.