Iso-propagation vortices: a breakthrough in optical communication technology

The rapid advance of optical communication technology requires improvements in data transmission capacity and efficiency.Conventional methods of increasing the transmission capacity such as polarization, wavelength, and spatial mode division multiplexing have shown significant promise, while spatial mode division multiplexing (SDM) offers a new approach through the use of orthogonal spatial modes as distinct communication channels.6][7] Furthermore, the orthogonality of different OAM modes increases their potential for multiplexing in communication systems to significantly increase the data capacity of communication devices.Each OAM mode can carry an independent data stream and be efficiently separated at the receiver with minimal crosstalk.The integration of OAM in optical communications holds potential for a variety of applications, including high-capacity free-space optical (FSO) links, fiber-optic systems, and even in quantum communication links.However, major challenges arise due to diffraction-induced expansion and divergence. 8,9As OAM beams propagate, diffraction causes them to expand and diverge, which reduces the spatial coherence and causes signal interference.These issues are especially pronounced over long distances that require additional compensators to maintain the