Nonlinear absorption characteristics of carbon quantum dots

Meiling Gao; Qing Chang

doi:10.1117/12.2197679

15 October 2015 Nonlinear absorption characteristics of carbon quantum dots

Meiling Gao, Qing Chang

Proceedings Volume 9671, AOPC 2015: Advances in Laser Technology and Applications; 96710A (2015) https://doi.org/10.1117/12.2197679
Event: Applied Optics and Photonics China (AOPC2015), 2015, Beijing, China

Abstract

In this paper, we use Z-scan technique to investigate the nonlinear absorption characteristics of water-soluble carbon quantum dots (CDs) that fluorescence emission wavelengths are 450 nm (sample 1) and 550 nm (sample 2) respectively. The nonlinear absorptions of sample 1 and sample 2 are saturated absorption and reverse saturable absorption under the nanosecond (ns) and picosecond (ps) laser pulse. Their nonlinear absorption coefficients are -2.2×10^-10m/W, 2.1×10^-10m/W under the ns laser pulse and -2.09×10^-12m/W, 1.9×10^-12m/W under the ps laser pulse. The nonlinear absorptions of sample 1 and sample 2 are reverse saturable absorption and saturated absorption under the femtosecond (fs) laser pulse. Their nonlinear absorption coefficients are 8.5×10^-13m/W and -4.3×10^-13m/W respectively. The experimental results show the signs of nonlinear absorptions for sample 1 and sample 2 are all opposite under the ns, ps and fs laser pulses respectively. The nonlinear absorption of sample 1 results from two-photon absorption. The nonlinear absorption of sample 2 results from two-photon absorption under the ns and ps laser pulses, and single photon absorption under the fs laser pulse. The analyses of experimental results show that the nonlinear absorption characteristics of CDs with different fluorescence emission wavelengths are different. The main reason dues to the different particle sizes of CDs, quantum size effects of CDs influence their nonlinear absorption characteristics.

Citation Download Citation

Meiling Gao and Qing Chang "Nonlinear absorption characteristics of carbon quantum dots", Proc. SPIE 9671, AOPC 2015: Advances in Laser Technology and Applications, 96710A (15 October 2015); https://doi.org/10.1117/12.2197679

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