Browsing by Author "Nalla, V."

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    Blue liquid lasers from solution of CdZnS/ZnS ternary alloy quantum dots with quasi ‐ continuous pumping
    (Wiley - VCH Verlag GmbH & Co. KGaA, 2015) Wang Y.; Leck K.S.; Ta, V. D.; Chen R.; Nalla, V.; Gao, Y.; He T.; Demir, Hilmi Volkan; Sun, H.
    A blue (ca. 440 nm) liquid laser with an ultra‐low threshold through which quasi‐continuous wave pumping is accessible is achieved by engineering unconventional ternary CdZnS/ZnS alloyed‐core/shell QDs. Such an achievement is enabled by exploiting the novel gain media with minimal defects, suppressed Auger recombination, and large gain cross‐section in combination with high‐quality‐factor whispering gallery mode resonators.
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    Unraveling the ultralow threshold stimulated emission from CdZnS/ZnS quantum dot and enabling high ‐ Q microlasers
    (Wiley-VCH Verlag, 2015) Wang Y.; Fong, K. E.; Yang, S.; Ta, V.; Gao, Y.; Wang, Z.; Nalla, V.; Demir, Hilmi Volkan; Sun, H.
    The newly engineered ternary CdZnS/ZnS colloidal quantum dots (CQDs) are found to exhibit remarkably high photoluminescence quantum yield and excellent optical gain properties. However, the underlying mechanisms, which could offer the guidelines for devising CQDs for optimized photonic devices, remain undisclosed. In this work, through comprehensive steady-state and time-resolved spectroscopy studies on a series of CdZnS-based CQDs, we unambiguously clarify that CdZnS-based CQDs are inherently superior optical gain media in the blue spectral range due to the slow Auger process and that the ultralow threshold stimulated emission is enabled by surface/interface engineering. Furthermore, external cavity-free high-Q quasitoroid microlasers were produced from self-assembly of CdZnS/ZnS CQDs by facile inkjet printing technique. Detailed spectroscopy analysis confirms the whispering gallery mode lasing mechanism of the quasitoroid microlasers. This tempting microlaser fabrication method should be applicable to other solution-processed gain materials, which could trigger broad research interests. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA.