Fiber integrated chalcogenide metasurface enabled phase and intensity modulation with built-in memory functionality

Abstract

Optical fibers are the main photonic technology platform that serve as the crucial high-speed connections between network nodes and servers across large distances; however, current electro-optic signal conversions present an energy intensive, bandwidth and data rate limited bottleneck. To realized next-generation communication transfer speeds (beyond 5G), a change in hardware architecture is required: the implementation of an all-optical network where signal generation, processing and routing is brought into the optical domain. Recently, planar phase change chalcogenide metamaterials have demonstrated all-optical switching, capable of intensity and phase modulation with built-in memory functionality (non-volatility) at a fraction of the operation wavelength in size[1-5]; thereby presenting an energy efficient, reconfigurable, and small footprint platform for integration onto optical fibers to functionalize this traditionally passive light guiding component. Here we present metadevices made from reconfigurable phase change chalcogenide (specifically Ge2Sb2Te5 composition) metamaterials on both optical fiber-tip and side-polished configurations. Integrated on a commercial single mode fiber tip, the cuboid GST metasurface exhibits large transmission contrasts between amorphous and crystalline phases and both normal and anomalous dispersion profiles ranging across the telecom bands for applications in signal broadening compensation. The metasurface periodicity enables spectral position control of dielectric Mie resonances, allowing for tunable operation across the telecom band. We also demonstrate that side-polished fiber integrated metadevices exhibit two types of resonances: one arising from thin film Fabry-Perot modes and another originating from metamaterial grating modes. By varying the period and thickness of the nanograting, the two resonant modes can be spectrally shifted to address applications in multi-band filtering and wavelength division multiplexing.