The nonlinear optical property of bandgap-tunable TMDs-PdSe2: Toward a generation mode for near-infrared ultrashort laser pulses

Abstract

Two-dimensional (2D) transition metal chalcogenides (TMDs) materials have been more and more important in various research fields such as nanoelectronics, spintronics, ultrafast photonics, etc. Optical materials with compositive functions have always been desired. This work successfully verified that 2D PdSe2 nanosheets have adjustable layers and tunable bandgaps. Besides, by using the 2D PdSe2 nanosheets as saturable absorption devices in a 2 μm solid-state laser, it is discovered that the 2D PdSe2 shows obvious nonlinear saturable absorption characteristics. Moreover, in the 2 μm Q-switched mode-locked laser, an ultrashort pulse laser output of 486.5 ps was achieved, proving the excellent ultrafast modulation characteristics of PdSe2. To insight into the relationship between the structure and its optical performances, theoretical modeling and calculations were implemented based on the layered structure of PdSe2. All the above indicates that the 2D PdSe2 could be promising saturable absorption devices and ultrafast photonic devices, which may promote the development of ultrashort lasers.