Title: Controlled Assembly of Upconverting Nanoparticles for Low-Threshold Microlasers and Their Imaging in Scattering Media

Abstract

Micron-sized lasers fabricated from upconverting nanoparticles (UCNP) coupled to whispering gallery mode (WGM) microresonators can exhibit continuous-wave anti-Stokes lasing useful for tracking cells, environmental sensing, and coherent stimulation of biological activity. The integration of these microlasers into organisms and microelectronics requires even smaller diameters, however, which raises threshold pump powers beyond practical limits for biological applications. To meet the need for low lasing thresholds and high fidelity fabrication methods, we use correlative optical and electron microscopy to uncover the nanoparticle assembly process and structural factors that determine efficient upconverted lasing. We show that 5 μm microspheres with controlled submonolayer UCNP coatings exhibit, on average, 25-fold lower laser thresholds (1.7 ± 0.7 kW/cm²) compared to the mean values of the lowest threshold UCNP lasers, and variability is reduced 30-fold. WGMs are observed in the upconversion spectra for TiO₂-coated microspheres as small as 3 μm, a size at which optical losses had previously prevented such observations. Finally, we demonstrate that the WGM signatures of these upconverting microlasers can be imaged and distinguished through tissue-mimicking phantoms. These advances will enable the fabrication of more efficient upconverting lasers for imaging, sensing, and actuation in optically complex environments.

Authors:

Liu, Yawei ^[1]; Teitelboim, Ayelet ^[2]; Fernandez-Bravo, Angel ^[2]; Yao, Kaiyuan ^[3]; Altoe, M. P. ^[2]; Aloni, Shaul ^[2]; Zhang, Chunhua  ^[4];

• Search DOE PAGES for author "Zhang, Chunhua"
• Search DOE PAGES for ORCID "0000-0002-8803-2415"

Cohen, Bruce E.  ^[2];

• Search DOE PAGES for author "Cohen, Bruce E."
• Search DOE PAGES for ORCID "0000-0003-3655-3638"

Schuck, P. James  ^[5];

• Search DOE PAGES for author "Schuck, P. James"
• Search DOE PAGES for ORCID "0000-0001-9244-2671"

Chan, Emory M.  ^[2]

• Search DOE PAGES for author "Chan, Emory M."
• Search DOE PAGES for ORCID "0000-0002-5655-0146"

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry; Harbin Institute of Technology (China). School of Chemistry and Chemical Engineering
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry
3. Columbia Univ., New York, NY (United States). Dept. of Mechanical Engineering; Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering
4. Harbin Institute of Technology (China). School of Chemistry and Chemical Engineering
5. Columbia Univ., New York, NY (United States). Dept. of Mechanical Engineering

Publication Date:

Thu Feb 13 00:00:00 EST 2020

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1779236

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

ACS Nano

Additional Journal Information:

Journal Volume: 14; Journal Issue: 2; Journal ID: ISSN 1936-0851

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

77 NANOSCIENCE AND NANOTECHNOLOGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; anti-Stokes laser; self-assembly; nanoparticle; microlaser; upconverison