Abstract

In our work, PbS/CdS core/shell quantum dots with an absorption peak of 1043 nm were successfully employed as a modulator for achieving a passively $Q$-switched Nd-doped fiber laser. The saturation intensity and modulation depth of the film-type modulator were $7.6\mathrm{MW}/{\mathrm{cm}}^2$ and 4.1%, respectively. Due to the protection of the CdS shell, the PbS core exhibited good photo-chemical stability, which led to the generation of stable passively $Q$-switched operation. The maximum average output power was 7.88 mW with a minimum pulse width of 235.7 ns. To our knowledge, this was the first demonstration focusing on the combination of quantum dot and Nd-doped fiber laser; in addition, 235.7 ns was the narrowest pulse width of a passively $Q$-switched Nd-doped fiber laser. Our results highlighted the excellent nonlinear absorption properties of PbS/CdS core/shell quantum dots and give significant guidance for future optical applications of quantum dots and demonstrations of pulsed Nd-doped fiber lasers.

© 2019 Optical Society of America

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