Nonlinear optical properties and applications of 2D metal oxides

Two-dimensional (2D) materials have stimulated continued interest due to their potential applications in fields from electronic, optical to catalysis and energy. Compared with the widely studied 2D metal chalcogenides, 2D oxides could be of particular interest for a ranges of applications where oxidative and high temperature conditions are involved. This feature of 2D oxides, combined with the inherent benefits of 2D systems could also be important for nonlinear optical (NLO) studies that involves strong light-matter interactions. Here we focus on the recent advances in the exploration of 2D metal oxides for nonlinear optics and ultrafast photonic applications. Along with a brief description of the crystal structures, fabrication methods and general properties of 2D oxides, we concentrate our discussion on the recent progresses in the nonlinear optical studies on 2D systems of both metallic and nonmetallic nature. The strong NLO absorption of these 2D oxides has been utilized for the development of optical switches for driving pulse generation in a number of fiber and solid-state lasers operating in the near infrared range. This review finally presents a brief analysis of main challenges of 2D metal oxides in the field nonlinear photonics and a short discussion on potential future directions.