Continuous-wave upconverting nanoparticle microlasers

Journal Article · Mon Jun 18 00:00:00 EDT 2018 · Nature Nanotechnology

DOI:https://doi.org/10.1038/s41565-018-0161-8· OSTI ID:1574385

Fernandez-Bravo, Angel; Yao, Kaiyuan ; Barnard, Edward S. ; Borys, Nicholas J.; Levy, Elizabeth S.; Tian, Bining; Tajon, Cheryl A.; Moretti, Luca; Altoe, M. Virginia; Aloni, Shaul; Beketayev, Kenes ; Scotognella, Francesco; Cohen, Bruce E. ; Chan, Emory M.; Schuck, P. James

Reducing the size of lasers to microscale dimensions enables new technologies¹ that are specifically tailored for operation in confined spaces ranging from ultra-high-speed microprocessors² to live brain tissue³. However, reduced cavity sizes increase optical losses and require greater input powers to reach lasing thresholds. Multiphoton-pumped lasers^4,5,6,7 that have been miniaturized using nanomaterials such as lanthanide-doped upconverting nanoparticles (UCNPs)⁸ as lasing media require high pump intensities to achieve ultraviolet and visible emission and therefore operate under pulsed excitation schemes. Here, we make use of the recently described energy-looping excitation mechanism in Tm³⁺-doped UCNPs⁹ to achieve continuous-wave upconverted lasing action in stand-alone microcavities at excitation fluences as low as 14 kW cm^-2. Continuous-wave lasing is uninterrupted, maximizing signal and enabling modulation of optical interactions¹⁰. By coupling energy-looping nanoparticles to whispering-gallery modes of polystyrene microspheres, we induce stable lasing for more than 5 h at blue and near-infrared wavelengths simultaneously. These microcavities are excited in the biologically transmissive second near-infrared (NIR-II) window and are small enough to be embedded in organisms, tissues or devices. The ability to produce continuous-wave lasing in microcavities immersed in blood serum highlights practical applications of these microscale lasers for sensing and illumination in complex biological environments.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1574385
• Journal Information: Nature Nanotechnology, Vol. 13, Issue 7; ISSN 1748-3387
• Publisher: Nature Publishing Group
• Country of Publication: United States
• Language: English