The nonlinear absorption of carbon quantum dots under the picosecond laser pulse

摘要

Using Z-scan technique to investigate the nonlinear absorption characteristics of carbon quantum dots (CDs) under the picosecond laser pulse with the wavelength of 532 nm, which the CDs' types were same particle size of different solvent and same solvent of different particle sizes. The experimental results showed that the nonlinear absorption of water-soluble CDs of 3.9 nm was saturated absorption, and oil-soluble CDs' was reverse saturable absorption for the same particle size, their nonlinear absorption coefficients were -2.09×10~(-12) m/W and 6.9×10~(-12) m/W, respectively; the nonlinear absorption of water-soluble CDs of 4.8 nm was reverse saturable absorption, and oil-soluble CDs' was saturated absorption for same particle size, their nonlinear absorption coefficients were 1.9×10~(-12) m/W and -1.3×10~(-12) m/W, respectively. The experimental results indicate that the nonlinear absorptions of CDs are mainly influenced by the solvent effect and quantum size effect in the same.