Electrochemical Peeling Few-Layer SnSe2 for High-Performance Ultrafast Photonics

Abstract

In recent years, the photoelectric properties and nonlinear optical properties of layered metal chalcogenides (LMCs) have attracted extensive attention. Because they have lower phonon thermal conductivity, larger energy storage rate, larger electron mobility, so they are widely studied in the fields of thermoelectric energy conversion, battery electrode materials, and semiconductor devices. As a 2D LMCs, SnSe2 nanosheets (Ns) are connected to each other by van der Waals force, which makes it possible to use electrochemical methods to help peel off the thin layer structure. Two-dimensional SnSe2 has obvious adjustable band gap characteristics. Its thickness can be controlled to keep it on the desired band gap. In this article, we prepared a thin layer of SnSe2 by electrochemical methods and detected its non-linear optical characteristics. It shows that our prepared materials have good optical absorption characteristics, it has modulation depth of 15% and saturation intensity of 61 MW/cm2. To investigate the nonlinear effects of SnSe2 in short and long cavities, respectively. The Q-mode-locking phenomenon was firstly achieved at a cavity length of 6m. After increasing the cavity length to 56m, the pump power was adjusted to achieve an adjustable repetition frequency from MHz to GHz in turn in an Er-doped fiber laser through utilizing a SnSe2 incorporating a tapered fiber as saturable absorber (SA) firstly. The nonlinear optical properties of thin-layer SnSe2 are fully proved, which opens a new way for advanced photonics, optical communication, laser measurement and other fields.