First-principles calculations of the frequency-dependent birefringence, second-harmonic generation, and linear electro-optic response are reported for LiGaO2 (which is transparent to as small as 222 nm). Good agreement is obtained with available experimental data in the visible region of the spectrum. The calculated frequency-dependent nonlinear optical responses are surprisingly constant in the entire energy region below the gap and small in absolute value (of the order of 0.2–1.2 pm/V for the various structures considered). Although the birefringence is insufficient for second-harmonic generation into the ultraviolet, opportunities may exist for sum-frequency generation. Angular phase-matching tuning curves are provided. The reasons for the low values of χ(2) are discussed. It is found to be not very sensitive to the structure and to arise in part from a large degree of cancellation between pure interband and mixed intra- and interband contributions.
© 1999 Optical Society of America
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.4400) Nonlinear optics : Nonlinear optics, materials
(190.4720) Nonlinear optics : Optical nonlinearities of condensed matter
Sergey N. Rashkeev, Sukit Limpijumnong, and Walter R. L. Lambrecht, "Theoretical evaluation of LiGaO2 for frequency upconversion to ultraviolet," J. Opt. Soc. Am. B 16, 2217-2222 (1999)