Long-range optical coupling with epsilon-near-zero materials
- Danqing Wang
- Zheyu Lu
- Sorren Warkander
- Niharika Gupta
- Qingjun Wang
- Penghong Ci
- Ruihan Guo
- Jiachen Li
- Ali Javey
- Jie Yao
- Feng Wang
- Junqiao Wu
2025-10-16
Long-range resonant quantum tunneling of electrons happens across potential barriers when the wavefunction interferes constructively outside the barrier. Here we demonstrate an analogy in optical systems based on epsilon-near-zero materials, achieving phase-modulated, long-range optical interactions between transparent semiconducting oxide layers beyond the evanescent photonic coupling. Distinct from weak thin-film interference, intense electromagnetic fields confined within the epsilon-near-zero thin films show anti-correlated intensity oscillations as a function of interlayer separation up to hundreds of microns. The oscillatory, anti-correlated electromagnetic field intensities were probed by second harmonic generation from wedged indium tin oxide multilayers. Such a system that hosts subwavelength mode footprint and simultaneously long-range radiative coupling offers prospects for long-distance optical communication, large-scale photonic circuits, and hybrid quantum photonic systems.