Ultra-broadband On-chip Twisted Light Emitter

On-chip twisted light emitters are essential components for orbital angular momentum (OAM) communication devices, which could address the growing demand for high-capacity communication systems by providing an additional degree of freedom for wavelength/frequency division multiplexing (WDM/FDM). Although whispering gallery mode enabled OAM emitters have been shown to possess some advantages, such as being compact and phase accurate, their inherent narrow bandwidth prevents them from being compatible with WDM/FDM techniques. Here, we demonstrate an ultra-broadband multiplexed OAM emitter that utilizes a novel joint path-resonance phase control concept. The emitter has a micron sized radius and nanometer sized features. Coaxial OAM beams are emitted across the entire telecommunication band from 1450 to 1650 nm. We applied the emitter for OAM communication with a data rate of 1.2 Tbit/s assisted by 30-channel optical frequency combs (OFC). The emitter provides a new solution to further increase of the capacity in the OFC communication scenario.