  The generation of rapidly tunable Optical Vortex (OV) beams is one of the
most demanding research areas of the present era as they possess Orbital
Angular Momentum (OAM) with additional degrees of freedom that can be exploited
to enhance signal-carrying capacity by using mode division multiplexing and
information encoding in optical communication. Particularly, rapidly tunable
OAM devices at a fixed wavelength in the telecom band stir extensive interest
among researchers for both classical and quantum applications. This article
demonstrates the realistic design of a Si-integrated photonic device for
rapidly tunable OAM wave generation at a 1550-nm wavelength by using an
ultra-low-loss Phase Change Material (PCM) embedded with a Si-ring resonator
with angular gratings. Different OAM modes are achieved by tuning the effective
refractive index using rapid electrical switching of Sb2Se3 film from amorphous
to crystalline states and vice versa. The generation of OAM waves relies on a
traveling wave modulation of the refractive index of the micro-ring, which
breaks the degeneracy of oppositely oriented whispering gallery modes. The
proposed device is capable of producing rapidly tunable OV beams, carrying
different OAM modes by using electrically controllable switching of
ultra-low-loss PCM Sb2Se3.
