Browsing by Author "Sun, H. D."
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Item Open Access Nanosecond colloidal quantum dot lasers for sensing(Optical Society of America, 2014) Guilhabert, B.; Foucher, C.; Haughey, A M.; Mutlugun, E.; Gao, Y.; Herrnsdorf, J.; Sun, H. D.; Demir, Hilmi Volkan; Dawson, M. D.; Laurand, N.Low-threshold, gain switched colloidal quantum dot (CQD) distributed-feedback lasers operating in the nanosecond regime are reported and proposed for sensing applications for the first time to the authors' knowledge. The lasers are based on a mechanically-flexible polymeric, second order grating structure overcoated with a thin-film of CQD/PMMA composite. The threshold fluence of the resulting lasers is as low as 0.5 mJ=cm2 for a 610 nm emission and the typical linewidth is below 0.3 nm. The emission wavelength of the lasers can be set at the design stage and laser operation between 605 nm and 616 nm, while using the exact same CQD gain material, is shown. In addition, the potential of such CQD lasers for refractive index sensing in solution is demonstrated by immersion in water. © 2014 Optical Society of America.Item Open Access Near resonant third-order optical nonlinearities of colloidal InP/ZnS quantum dots(AIP Publishing, 2013) Wang, Y.; Yang, X.; He, T. C.; Gao, Y.; Demir, Hilmi Volkan; Sun, X. W.; Sun, H. D.We have investigated the third-order optical nonlinearities of high-quality colloidal InP/ZnS core-shell quantum dots (QDs) using Z-scan technique with femtosecond pulses. The two-photon absorption cross-sections as high as 6.2 × 103 GM are observed at 800 nm (non-resonant regime) in InP/ZnS QDs with diameter of 2.8 nm, which is even larger than those of CdSe, CdS, and CdTe QDs at similar sizes. Furthermore, both of the 2.2 nm and 2.8 nm-sized InP/ZnS QDs exhibit strong saturable absorption in near resonant regime, which is attributed to large exciton Bohr radius in this material. These results strongly suggest the promising potential of InP/ZnS QDs for widespread applications, especially in two-photon excited bio-imaging and saturable absorbing.Item Open Access Stimulated emission and lasing from CdSe/CdS/ZnS core-multi-shell quantum dots by simultaneous three-photon absorption(Wiley - V C H Verlag GmbH, 2014) Wang Y.; Ta, V. D.; Gao, Y.; He, T. C.; Chen R.; Mutlugun, E.; Demir, Hilmi Volkan; Sun, H. D.Three-photon pumped stimulated emission and coherent random lasing from colloidal CdSe/CdS/ZnS core-multishell quantum dots are achieved for the first time. These results can offer new possibilities in biology and photonics, as well as at their intersection of biophotonics.