Optical communications using orbital angular momentum beams

Abstract

Orbital angular momentum (OAM), which describes the "phase twist" (helical phase pattern) of light beams, has recently gained interest due to its potential applications in many diverse areas. Particularly promising is the use of OAM for optical communications since: (i) coaxially propagating OAM beams with different azimuthal OAM states are mutually orthogonal, (ii) inter-beam crosstalk can be minimized, and (iii) the beams can be efficiently multiplexed and demultiplexed. As a result, multiple OAM states could be used as different carriers for multiplexing and transmitting multiple data streams, thereby potentially increasing the system capacity. In this paper, we review recent progress in OAM beam generation/detection, multiplexing/demultiplexing, and its potential applications in different scenarios including free-space optical communications, fiber-optic communications, and RF communications. Technical challenges and perspectives of OAM beams are also discussed.

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

“…Similarly, mode-division multiplexing of rotationally asymmetric linearly polarised (LP) modes requires 3D waveguides [140]. Also optical angular momentum (OAM) beams can be used for mode-division multiplexing [141]. This approach is in particular attractive for free-space optical communication with a recent demonstration of using a hybrid 3D photonic circuit for multiplexing and demultiplexing of different OAM beams [7].…”

“…Like the LP modes, OAM can also be used as an orthogonal basis set of modes for mode-division multiplexing in order to scale the transmission capacity of fibre as well as free-space communication links [141]. An OAM beam exhibits a helical phase front, where the OAM order is the number of 2π phase shifts in a circle around the beam axis.…”

Novel Equalization Techniques for Space Division Multiplexing Based on Stokes Space Update Rule

“…Alternatively, another set of orthogonal modes may be excited, like orbital angular momentum (OAM) modes, that exhibit less degeneracy of propagation constant and thus less severe (resonant) crosstalk between the modes. The generation of OAM modes can be done by means of ring resonators or its conversion by free space optics employing Spatial Light Modulators (SLM) [15]. OAM modes also require the design of specific optical fibers that are capable of removing aforementioned degeneracy and thus of suppressing mode coupling such as the inverse-parabolic graded-index fiber (IPGIF) [16].…”

Calculation of a mode set in weakly guiding fibers

“…The essence of mode division multiplexing is as follows: as a linear superposition of fiber modes, laser beams can be used to generate signals that will effectively transmit data in a physical carrier -a multimodal fiber; the data transmitted can be contained both in the modal composition and in the energy portion associated with each laser mode [3][4][5][6][7][8][9][10][11][12][13]. In addition, the division of the vortex basis connected with orbital angular momentum is especially perspective [7][8][9][10][11][12][13][14].…”