Browsing by Author "Ta, V. D."

Now showing 1 - 6 of 6

Open Access
Anisotropic stimulated emission from aligned CdSe/CdS dot-in-rods
(IEEE, 2014-10) Gao, Y.; Ta, V. D.; Zhao, X.; Wang, Y.; Chen, R.; Zhao, Y.; Dang, C.; Sun, X.; Sun, H.; Demir, Hilmi Volkan
Anisotropic optical properties of CdSe/CdS dot-in-rods loaded in a capillary tube are demonstrated, suggesting nanorods' alignment with a microfluidic approach. Polarized emissions from photoluminescence and whispering gallery mode lasing show promising applications for lighting and displays. © 2014 IEEE.
Open Access
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.
Open Access
Observation of polarized gain from aligned colloidal nanorods
(Royal Society of Chemistry, 2015) Gao, Y.; Ta, V. D.; Zhao, X.; Wang Y.; Chen R.; Mutlugün, E.; Fong, K. E.; Tan S.T.; Dang C.; Sun, X. W.; Sun, H.; Demir, Hilmi Volkan
In recent years, colloidal semiconductor nanorods have attracted great interest for polarized spontaneous emission. However, their polarized gain has not been possible to achieve so far. In this work we show the highly polarized stimulated emission from the densely packed ensembles of core-seeded nanorods in a cylindrical cavity. Here CdSe/CdS dot-in-rods were coated and aligned on the inner wall of a capillary tube, providing optical feedback for the nanorod gain medium. Results show that the polarized gain originates intrinsically from the aligned nanorods and not from the cavity and that the optical anisotropy of the nanorod ensemble was amplified with the capillary tube, resulting in highly polarized whispering gallery mode lasing. The highly polarized emission and lasing, together with easy fabrication and flexible incorporation, make this microlaser a promising candidate for important color conversion and enrichment applications including liquid crystal display backlighting and laser lighting. This journal is © The Royal Society of Chemistry.
Open Access
Reconfigurable Liquid Whispering Gallery Mode Microlasers
(Nature Publishing Group, 2016) Yang, S.; Ta, V. D.; Wang, Y.; Chen, R.; He, T.; Demir, Hilmi Volkan; Sun, H.
Engineering photonic devices from liquid has been emerging as a fascinating research avenue. Reconfigurably tuning liquid optical micro-devices are highly desirable but remain extremely challenging because of the fluidic nature. In this article we demonstrate an all-liquid tunable whispering gallery mode microlaser floating on a liquid surface fabricated by using inkjet print technique. We show that the cavity resonance of such liquid lasers could be reconfigurably manipulated by surface tension alteration originated from the tiny concentration change of the surfactant in the supporting liquid. As such, remarkable sensing of water-soluble organic compounds with a sensitivity of free spectral range as high as 19.85 THz/(mol · mL-1) and the detectivity limit around 5.56 × 10-3 mol · mL-1 is achieved. Our work provides not only a novel approach to effectively tuning a laser resonator but also new insight into potential applications in biological, chemical and environmental sensing.
Open Access
Robust whispering-gallery-mode microbubble lasers from colloidal quantum dots
(American Chemical Society, 2017) Wang Y.; Ta, V. D.; Leck K.S.; Tan, B. H. I.; Wang, Z.; He T.; Ohl, C.-D.; Demir, Hilmi Volkan; Sun, H.
Microlasers hold great promise for the development of photonics and optoelectronics. Among the discovered optical gain materials, colloidal quantum dots (CQDs) have been recognized as the most appealing candidate due to the facile emission tunability and solution processability. However, to date, it is still challenging to develop CQD-based microlasers with low cost yet high performance. Moreover, the poor long-term stability of CQDs remains to be the most critical issue, which may block their laser aspirations. Herein, we developed a unique but generic approach to forming a novel type of a whispering-gallery-mode (WGM) microbubble laser from the hybrid CQD/poly(methyl methacrylate) (PMMA) nanocomposites. The formation mechanism of the microbubbles was unraveled by recording the drying process of the nanocomposite droplets. Interestingly, these microbubbles naturally serve as the high-quality WGM laser resonators. By simply changing the CQDs, the lasing emission can be tuned across the whole visible spectral range. Importantly, these microbubble lasers exhibit unprecedented long-term stability (over one year), sufficient for practical applications. As a proof-of-concept, the potential of water vapor sensing was demonstrated. Our results represent a significant advance in microlasers based on the advantageous CQDs and may offer new possibilities for photonics and optoelectronics.
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.