LAUSR

We theoretically investigate the dipolar whispering-gallery modes (WGMs) with different mode orders supported by spherical hyperbolic metamaterial (HMM) cavities consisting of alternating metal and dielectric layers. Associated with the excitations of the WGMs with the highest and the second highest mode orders, the HMM cavities are capable of creating highly enhanced and uniformly distributed local fields in the entire dielectric core region. Variation on the metal filling ratio allows for easily tuning the resonant wavelengths of WGMs over a wide spectral range. By integrating a nonlinear nanocrystal into the HMM cavities, we show enhancements of intensity of second harmonic generation up to a factor of 3.9 × 1010, which is two orders of magnitude higher than the largest enhancement achieved in the single-layer plasmonic core-shell cavities.