Characterizations of the nonlinear optical properties for (010) and (2¯01) beta-phase gallium oxide

• Published in: Optics express 2018-02, Vol.26 (4), p.3938-3946
• Main Authors: Chen, Hong, Fu, Houqiang, Huang, Xuanqi, Montes, Jossue A, Yang, Tsung-Han, Baranowski, Izak, Zhao, Yuji
• Format: Article
• Language: English
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.26.003938

We report, for the first time, the characterizations on optical nonlinearities of beta-phase gallium oxide (β-Ga O ), where both (010) β-Ga O and (2¯01) β-Ga O were examined for two-photon absorption coefficient, Kerr nonlinear refractive index, and their polarization dependence. The wavelength dependence of two-photo absorption coefficient and Kerr nonlinear refractive index were also estimated by a widely used analytical model. β-Ga O exhibits a two photon absorption (TPA) coefficient of 1.2 cm/GW for (010) β-Ga O and 0.6 cm/GW for (2¯01) β-Ga O . The Kerr nonlinear refractive index is -2.1 × 10 cm /W for (010) β-Ga O and -2.9 × 10 cm /W for (2¯01) β-Ga O . In addition, β-Ga O shows stronger in-plane nonlinear optical anisotropy on (2¯01) plane than on (010) plane. Compared with GaN, TPA coefficient of β-Ga O is 20 times smaller, and the Kerr nonlinear refractive index of β-Ga O is also found to be 4-5 times smaller. These results indicate that β-Ga O have the potential for ultra-low loss waveguides and ultra-stable resonators and integrated photonics, especially in UV and visible wavelength spectral range.