Subwavelength metallic cavities with high-Qresonance modes

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.2

Ultrahigh quality factor in a metal-embedded semiconductor microdisk cavity

“…The metallic nanocavities have also been numerically characterized and the higher Q factors of ∼1700 [12] and ∼ 3400 [13] have been reported. Recently, higher Q factor about 5000 at room temperature [14] and 9000 at 20 K [15] have been demonstrated in a metal-embedded cavity. Although high Q factor in a metallic cavity has been experimentally demonstrated, the generation mechanism of the high Q factor is not fully clarified so far.…”