On-fiber photonic nanojet enables super-resolution in en face optical coherence tomography and scattering nanoscopy

Abstract Photonic nanojet (PNJ) of subwavelength spot-size originating at shadow side of a microsphere is projected as an imperative optical tool for micro-nano optics applications. Lack of a free hold PNJ source limits its vast potential. A state-of-the-art PNJ is introduced on a chemically etched...

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Bibliographic Details
Main Authors: Kaushal Vairagi, Jasleen Kaur, Pooja Gupta, Stefan Enoch, Samir K. Mondal
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Communications Physics
Online Access:https://doi.org/10.1038/s42005-025-02007-2
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Summary:Abstract Photonic nanojet (PNJ) of subwavelength spot-size originating at shadow side of a microsphere is projected as an imperative optical tool for micro-nano optics applications. Lack of a free hold PNJ source limits its vast potential. A state-of-the-art PNJ is introduced on a chemically etched encaved optical fiber nanoprobe holding a microsphere. Nanoprobe generating optical beam of spot-size ~2 μm, is focused on the microsphere resulting in PNJ of varying spot-size, 0.8λ to 0.5λ, over its’ length ~13λ at 660 nm wavelength. A PNJ centered around 840 nm wavelength combined with an effective numerical aperture ~2 results in an en-face optical coherence tomography (OCT) image of lateral resolution ~247 nm and phase map with optical thickness, ~70 nm for a standard DVD. Further, the PNJ based backscattered nanoscopy of silver nano-particles is exhibited with resolution ~40 nm. This commercially viable PNJ head can be an ideal platform for various microscopies and other applications.
ISSN:2399-3650