Comprehensive study on the nonlinear optical properties of few-layered MoSe2 nanosheets at 1 μm

The few-layered molybdenum diselenide (MoSe2) nanosheets were synthesized by the simple and low-cost ultrasonic-assisted liquid phase exfoliation (UALPE) method. The high quality of the two-dimensional nanostructures was verified by comprehensive characterization. The nonlinear optical properties including nonlinear absorption and refraction of the MoSe2 nanosheets were investigated by utilizing the open-and closed-aperture Z-scan technique. The MoSe2 nanosheets exhibits excellent nonlinear saturable and reverse saturable absorption for nanosecond laser pulses at 1 mu m. The two photon absorption (TPA) coefficient, nonlinear refractive index n(2), real and imaginary parts of the third-order nonlinear optical susceptibility were determined as 2.7 cm/MW, 2 x 10(-4) cm(2)/GW, 8.2 x 10(-12) esu and 1.61 x 10(-12) esu, respectively. Finally, the passively Q-switched Nd:CNGG laser with MoSe2 saturable absorber at 1.06 mu m was realized for the first time, showing the excellent satuable absorption properties. (C) 2019 Elsevier B.V. All rights reserved.