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High-Q surface-plasmon-polariton whispering-gallery microcavity

Min, Bumki and Ostby, Eric and Sorger, Volker and Ulin-Avila, Erick and Yang, Lan and Zhang, Xiang and Vahala, Kerry (2009) High-Q surface-plasmon-polariton whispering-gallery microcavity. Nature, 457 (7228). pp. 455-459. ISSN 0028-0836. doi:10.1038/nature07627.

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Surface plasmon polaritons (SPPs) are electron density waves excited at the interfaces between metals and dielectric materials (1). Owing to their highly localized electromagnetic fields, they may be used for the transport and manipulation of photons on subwavelength scales (2-9). In particular, plasmonic resonant cavities represent an application that could exploit this field compression to create ultrasmall-mode-volume devices. A key figure of merit in this regard is the ratio of cavity quality factor, Q (related to the dissipation rate of photons confined to the cavity), to cavity mode volume, V (refs 10, 11). However, plasmonic cavity Q factors have so far been limited to values less than 100 both for visible and near-infrared wavelengths (12-16). Significantly, such values are far below the theoretically achievable Q factors for plasmonic resonant structures. Here we demonstrate a high-Q SPP whispering-gallery microcavity that is made by coating the surface of a high-Q silica microresonator with a thin layer of a noble metal. Using this structure, Q factors of 1,376 ± 65 can be achieved in the near infrared for surface-plasmonic whispering-gallery modes at room temperature. This nearly ideal value, which is close to the theoretical metal-loss-limited Q factor, is attributed to the suppression and minimization of radiation and scattering losses that are made possible by the geometrical structure and the fabrication method. The SPP eigenmodes, as well as the dielectric eigenmodes, are confined within the whispering-gallery microcavity and accessed evanescently using a single strand of low-loss, tapered optical waveguide (17, 18). This coupling scheme provides a convenient way of selectively exciting and probing confined SPP eigenmodes. Up to 49.7 per cent of input power is coupled by phase-matching control between the microcavity SPP and the tapered fibre eigenmodes.

Item Type:Article
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URLURL TypeDescription
Zhang, Xiang0000-0003-4004-5185
Vahala, Kerry0000-0003-1783-1380
Additional Information:© 2009 Nature Publishing Group. Received 12 July; accepted 6 November 2008. We thank R. F. Oulton and G. Bartal for discussions and S. Zhang for a critical reading of the manuscript. This work was supported by the US Air Force Office of Scientific Research MURI program (grant no. FA9550-04-1-0434) and by the NSF Nanoscale Science and Engineering Center under award no. DMI-0327077.
Funding AgencyGrant Number
Air Force Office of Scientific ResearchFA9550-04-1-0434
National Science FoundationDMI-0327077
Issue or Number:7228
Record Number:CaltechAUTHORS:MINnat09
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13284
Deposited By: Tony Diaz
Deposited On:10 Feb 2009 00:46
Last Modified:08 Nov 2021 22:36

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