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QD-based-laser-2013Quantum Dots Laser Developed

In a search for a more reliable and tuneable laser sources, a group of scientists led by Prof. Lee from the National Cheng Kung University of Taiwan developed a quantum-dots based laser. Colloidal quantum dots (QD) of CdSe/ZnS were embedded into a cholesteric liquid crystal matrix. The article is soon to be published in Advanced Optical Materials.

Liquid crystals, which have photonic crystal behaviour, are already used in construction of dye-doped lasers, which, however, have several drawbacks such as thermal, chemical and photo- instabilities. 

This study was the first to report a highly directional lasing emission based on a QD-embedded CLC (QDCLC) cell. Experimental results showed that the QDs had a key function not only as the nanoscaled source of fluorescence emission but also as the structural stabilizer of the CLC microresonator. 

Comparing the developed QD-laser with the existing dye-doped laser, Prof. Lee said,  "The developed QDCLC laser could tolerate a strong pumped energy without damage (over 83 μ J/pulse), and this threshold is over 1.66 times higher than that (50 μ J/pulse) of a traditional DDCLC laser. The divergence angle of the QDCLC lasing emission is 1.67 times smaller than that of the DDCLC lasing emission. Furthermore, the QDCLC laser has flexibly thermal and electrical tunabilities in the lasing threshold, linewidth, and wavelength." 

"Combining the QD gain medium and the tunable CLC resonator can potentially result in the fabrication of tunable coherent light sources or laser devices (e.g., tunable single photon laser) with advantages of low cost, highly fl exible tunability, high stability, high damage threshold, lower beam divergence, and high reusability" Prof. Lee said.

All of the materials used in this study including CdSe/ZnS quantum dots are commercially available.

Related articles:
QDs Plus MOF for enhanced Light-Harvesting
Quantum Dots Can Shine Even Brighter

NanoJam (C) 2013
Image Source: John Wiley & Sons, Inc
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