Photonic meta-switch based on phase change and catenary-enabled continuous phase regulation

Abstract

Aiming at the characteristics of passive and discrete phase regulations inherent in current metasurfaces, we combine optimized isowidth catenary with non-volatile phase change dielectrics and explore a type of bistable phase-change-based wavefront meta-switch of continuous phase tuning and active switching. First, the switchable wavefront deflector is demonstrated in the mid-IR range between 9 µm and 10 µm. Upon phase transition between crystalline state and amorphous state, the incident wave can be switched into anomalous reflection and regular reflection, i.e. the “on” state and “off ” state of wave deflection. Further, a type of dynamically tunable Bessel beam switch is demonstrated. In the amorphous state, the polarization conversion efficiency approaches to 100% with an incident wave of 9.6 µm in wavelength. Therefore, the normal geometrical phase and the second-order Bessel focus are switched “on”. However, the cross-polarization and geometrical phase are switched “off ” upon phase changing into crystallized state. Intrinsically, non-dispersive spin-orbit interaction ensures that this kind of device possesses the broadband characteristics. Such a devise has great potential applications in active optoelectronic integration, optical communications, etc.