Ishihara N, Kurosawa H, Takemoto R, Jahan NA, Nakajima H, Kumano H, Suemune I. Subwavelength metallic cavities with high-Q resonance modes.
NANOTECHNOLOGY 2015;
26:085201. [PMID:
25648417 DOI:
10.1088/0957-4484/26/8/085201]
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Abstract
Metallic cavities have been extensively studied to realize small-volume nanocavities and nanolasers. However cavity-resonance quality (Q) factors of nanolasers observed up to now remain low (up to ∼500) due to metal optical absorption. In this paper, we report the observation of highest Q factors of 9000 at low temperature and ∼6000 near room temperature in a metallic cavity with a probe of sub-bandgap emission of Si-doped GaAs. We analyze the temperature dependence of cavity-mode resonance wavelengths and show that the refractive-index term dominates the measured temperature dependence. We also show that this refractive-index term is cavity-mode dependent and the fitting procedure offers a new method to identify cavity modes. We simulate the metallic cavity with finite-element method and attribute the high-Q cavity mode to a whispering gallery optical mode. This mode is shown to have isotropic polarization dependence of the output emission, which is preferable for quantum information applications.
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