Linear and nonlinear optical susceptibilities for a novel borate oxide BaBiBO4: Theory and experiment

The linear and nonlinear optical susceptibilities for different tensor components of BaBiBO4 single crystals have been calculated using the full-potential linear augmented plane wave method. The results of these calculations are verified by our measurements of linear and nonlinear optical properties using Nd-YAG laser at fundamental wavelength 1064 nm. The calculated energy gap is in a good agreement with experimental energy gap data obtained by optical absorption. We present results for the imaginary and real parts of the frequency-dependent dielectric constant. The calculated birefringence of BaBiBO4 is positive in agreement with the experimental data. Calculations are reported for the frequency-dependent complex part of second-order nonlinear optical susceptibilities χijk(2)(ω). The linear and nonlinear optical susceptibilities are scissors corrected to match the value of the energy gap from the local density approximation calculations with the experimental value. The second harmonic generation efficiency of this compound is about five times larger than KDP (KH2PO4). It is crucial that we have obtained a large anisotropy of the second-order susceptibilities for three main second-order tensor components χzzz(2)(ω),χxxz(2)(ω),andχyyz(2)(ω) both experimentally and theoretically. The possible origin of the obtained anisotropy is discussed within a framework of the energy band calculations. - Graphical abstract: Principal crystalline structure