Broadband nonlinear optical response and sub-picosecond carrier dynamics in graphene-SnSe₂ van der Waals heterostructures

Abstract

The van der Waals (vdWs) heterostructures, with vertical layer stacking structure of various two-dimensional (2D) materials, maintain the reliable photonic characteristics while compensating the shortcomings of the participating individual components. In this work, we combine the less-studied multilayer tin selenide (SnSe2) thin film with one of the traditional 2D materials, graphene, to fabricate the graphene-based vdWs optical switching element (Gr-SnSe2) with superior broadband nonlinear optical response. The transient absorption spectroscopy (TAS) measurement results verify that graphene acts as the recombination channel for the photogenerated carrier in the Gr-SnSe2 sample, and the fast recovery time can be reduced to hundreds of femtoseconds which is beneficial for the optical modulation process. The optical switching properties are characterized by the I-scan measurements, exhibiting a saturable energy intensity of 2.82 mJ·cm-2 (0.425 µJ·cm-2) and a modulation depth of 15.6% (22.5%) at the wavelength of 1030 nm (1980nm). Through integrating Gr-SnSe2 with a cladding waveguide, high-performance picosecond Q-switched operation in the near-infrared (NIR) and mid-infrared (MIR) spectral regions are both achieved. This work experimentally demonstrates the great potential of graphene-based vdWs heterostructures for applications in broadband ultrafast photonics.

Nonlinear Optical Saturable Absorption Properties of 2D VP Nanosheets and Application as SA in a Passively Q-Switched Nd:YVO4 Laser

“…where the value of modulation depth ∆R, saturation intensity I s , and nonsaturable losses can be obtained as 6.3%, 329 kW/cm The pump-probe techniques, open aperture Z-scan, and I-scan were performed characterize the ultrafast carrier dynamics and nonlinear optical response of the prepa 2D VP-SA. Ultrafast carrier dynamics in semiconductors play an important role in p tonics and optoelectronics [37,38]. The schematic diagram of the nondegenerate pum probe experimental setup is shown in Figure 4a.…”