Nonlinear saturable absorption properties of indium selenide and its application for demonstrating a Yb-doped mode-locked fiber laser

Abstract

Recently, two-dimensional materials have shown excellent nonlinear absorption properties and have practically promoted the development of ultrafast lasers. As one of the typical III-VI semiconductors, InSe has already been widely applied in designing photo-sensors and other optical devices due to its outstanding electrical transport, quantum physics and dramatic photo-response properties. However, the nonlinear absorption characteristics of InSe have not been experimentally investigated within ultrafast lasers so far. In our work, the nonlinear absorption properties of InSe were investigated. InSe-PVA film was successfully prepared and employed for achieving a mode-locked Yb-doped fiber laser. A stable mode-locked operation with a maximum output power of 16.3 mW and a minimum pulse width of 1.37 ns at a pulse repetition rate of 1.76 MHz was obtained, and the corresponding pulse energy was as high as 9.26 nJ. Our findings suggest that InSe may have wide potential ultrafast photonic applications due to its suitable bandgap value and excellent nonlinear saturable absorption characteristics.