Orbital angular momentum of light for communications

Abstract

Structured light, especially beams carrying orbital angular momentum (OAM), has gained much interest due to its unique amplitude and phase structures. In terms of communication systems, multiple orthogonal OAM beams can be potentially utilized for increasing link capacity in different scenarios. This review describes challenges, advances, and perspectives on different aspects of the OAM-based optical communications, including (a) OAM generation/detection and (de)multiplexing, (b) classical free-space optical communication links, (c) fiber-based communication links, (d) quantum communication links, (e) OAM-based communications in different frequency ranges, (f) OAM-based communications using integrated devices, and (g) novel structured beams for communications.

Towards higher-dimensional structured light

“…Here the many DoFs and dimensionality of structured light come to the fore. The idea is to exploit the spatial degree of freedom of light, referred to as space-division multiplexing (SDM) 31 , 32 or its sister mode division multiplexing (MDM) 33 , for more channels and more capacity per channel, and has gained momentum in recent years (see refs., 10 – 12 , 34 – 37 for recent reviews). Topical among the multiplexing techniques is the use of OAM modes, particularly in conjunction with other DoFs 38 , as illustrated in Fig.…”

Divergence-degenerate spatial multiplexing towards future ultrahigh capacity, low error-rate optical communications

“…Multiplexing of independent optical degrees of freedom (DoFs) such as polarization and wavelength have long been implemented to increase the capacity of optical communication systems 1 – 4 . The exploration of spatial DoFs of optical fields has offered new possibilities that mode-division-multiplexing (MDM) scales the capacity by a factor equal to the number of spatial modes acting as independent information channel carriers 5 – 9 . Among all spatial modes, the use of orbital angular momentum (OAM) beams, which can accommodate theoretically infinite orthogonal modes, has generated widespread and significant interest in the last decade 10 – 18 .…”

Mode‐switchable orbit angular momentum waves by mechanically rotating 2 bit phase quantization transmitarray

“…OAM was first simulated in the radio frequency (RF) band in 2007 2 and experimentally verified in 2011 3 . OAM beams have been extensively applied in many fields such as biomedicine, particle manipulation, detecting spinning object, imaging, and both quantum and classical communications because OAM can improve communication capacity greatly and solve the problem of spectrum scarcity 4–8 …”

“…3 OAM beams have been extensively applied in many fields such as biomedicine, particle manipulation, detecting spinning object, imaging, and both quantum and classical communications because OAM can improve communication capacity greatly and solve the problem of spectrum scarcity. [4][5][6][7][8] In general, generating RF or millimeter vortex waves carrying OAM can be divided into two methods: (1) Direct generation using antennas, such as phased array antennas (usually circular arrays), 9 traveling-wave antenna, 10 dielectric resonator antenna, 11 substrate integrated cavity resonator antenna, 12 active single microstrip patch antennas, 13 and so forth. (2) Indirect generation by reflection or transmission, such as spiral phase plate, 14 the helical parabolic antenna, 15 planar metasurface (MS) 16 and so on.…”