Gallium oxide-based optical nonlinear effects and photonics devices

Photonics devices working in the ultraviolet and visible (UV–Vis) spectra have drawn great attention due to their potential applications in the optical computing, communication, and bio-chemical sensing fields. Due to its wide bandgap, broadband transparency, low cost, and high thermal/chemical stability, gallium oxide (Ga2O3) semiconductor has emerged as a new platform for UV–Vis nonlinear optics and integrated photonics. In this paper, we review the recent studies on its nonlinear properties and applications for photonic devices. First, we introduce its different polymorphs and growth methods. Second, we present its basic optical properties. Third, we discuss its optical nonlinear effects including two-photon absorption, optical Kerr effect, photoluminescence, and Raman effect. Finally, we discuss the recent progress of photonics and optoelectronic devices based on Ga2O3 including waveguides and photodetectors. With the rapid development of Ga2O3 technologies, we fully expect more advanced photonic devices emerging on this exciting new photonic material platform.