Title: Ultra-broadband On-chip Twisted Light Emitter,
Abstract: 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.