Related Experiment Video
Updated: Jan 8, 2026

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Strong coupling of double resonance designs and epsilon-near-zero modes for mode-matching enhancement of
Ai-Yin Liu1, Chun-Hsiang Tseng2, Kuang-I Lin3
1Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, 10617, Taiwan.
Abstract:
We investigate the coupling effects between a double-resonance split-ring resonators (SRRs) design and the epsilon-near-zero (ENZ) guided mode of ultrathin indium tin oxide (ITO) films on second-harmonic generation (SHG). The optimized SRRs with an aspect ratio of 0.3 support a magnetic dipole (MD) resonance within the ENZ regime of ITO and a higher-order resonance at the SH frequency to achieve mode matching under cross-polarized excitation. The SRR-ITO coupled system (as opposed to the nanorod-ITO coupled system) was found to perform constructive (destructive) polarization interference between the nonlinear polarization currents at the upper hybridized modes (ω+) and the linear electric field at SH frequency (2ω+), resulting in a 1218-fold SHG enhancement outperformed than that of the nanorod-ITO coupled system, as predicted by overlap integral analysis. The measured SHG conversion efficiency for the SRR-ITO coupled system exceeds 10-7 at an excitation wavelength of 1,320 nm, corresponding to a one-order (two-order) of magnitude enhancement compared to the nanorod-ITO coupled system (Au/ITO film). These findings highlight the potential of the proposed hybrid metasurfaces for efficient cross-polarized nonlinear signal generation, paving the way for advanced applications such as light sources, modulators in integrated photonic circuits, and biological sensing.
Related Concept Videos
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
Sound Waves: Resonance
¹H NMR Signal Multiplicity: Splitting Patterns
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...

