Epsilon-near-zero (ENZ) thin films facilitate strong light-matter interactions with a widespread impact in nonlinear, quantum and thermal photonics. Here, we extend the scope of thin film ENZ modes by elucidating the generalized polaritonic modes emerging from anisotropy and near-zero permittivity. Through a theoretical investigation of generalized ENZ polaritons on silicon carbide (SiC) metasurfaces, we reveal a complex polaritonic landscape, consisting of a seven-region phase diagram. We show that the complex interplay between material properties and geometry changes the nature of the modes, and we clarify when ENZ modes with closed and open isofrequency curves (IFCs) can be observed, and how they coexist with surface phonon-polaritons and hyperbolic modes. The associated photonic topological transitions are accompanied by phase velocity sign reversals and induce dramatic modifications of near-field profiles and Purcell enhancement factors. Our work merges insights from anisotropic and ENZ effects, enabling enhanced control over polariton behavior with broad implications for subwavelength optics, material design, nonlinear effects, thermal emission, and quantum technologies.
Femtosecond all-optical polarization manipulation of harmonic generation in an anisotropic strongly coupled plasmon-epsilon-near-zero metasurface
Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Xi’an Jiaotong University（教育部光电技术与器件重点实验室、陕西省信息光子技术重点实验室，西安交通大学电子科学与工程学院）
