Characterizations of the Nonlinear Optical Properties for (010) and (-201) Beta-phase Gallium Oxide

• Published in: arXiv.org 2017-12
• Main Authors: Chen, Hong, Fu, Houqiang, Huang, Xuanqi, Montes, Jossue A, Tsung-Han, Yang, Baranowski, Izak, Zhao, Yuji
• Format: Article
• Language: English
• Subjects: Anisotropy; Beta phase; Coefficients; Crystal structure; Dependence; Gallium nitrides; Gallium oxides; Mathematical models; Optical properties; Photon absorption; Photonics; Refractivity; Waveguides
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1712.01390

We report, for the first time, the characterizations on optical nonlinearities of beta-phase gallium oxide (\b{eta}-Ga2O3), where both (010) \b{eta}-Ga2O3 and (-201) \b{eta}-Ga2O3 were examined for two-photon absorption (TPA) coefficient, Kerr refractive index, and their polarization dependence. The wavelength dependence of the TPA coefficient and Kerr refractive index was estimated using a widely used analytical model. \b{eta}-Ga2O3 exhibits a TPA coefficient of 1.2 cm/GW for (010) \b{eta}-Ga2O3 and 0.58 cm/GW for (-201) \b{eta}-Ga2O3. The Kerr refractive index is -2.14*10^(15) cm2/W for (010) \b{eta}-Ga2O3 and -2.89*10^(15) cm2/W for (-201) \b{eta}-Ga2O3. In addition, \b{eta}-Ga2O3 shows stronger nonlinear optical anisotropy on the (-201) plane than on the (010) plane, possibly due to highly asymmetric crystal structure. Compared with that of gallium nitride (GaN), the TPA coefficient of \b{eta}-Ga2O3 is 20 times smaller, and the Kerr refractive index of \b{eta}-Ga2O3 is also found to be 4 to 5 times smaller. These results indicate that \b{eta}-Ga2O3 has the potential for use in ultra-low loss waveguides and ultra-stable resonators and integrated photonics, especially in the UV and visible wavelength spectral range.