Massive individual orbital angular momentum channels for multiplexing enabled by Dammann gratings

TLDR

Optical communication is approaching the limits of conventional multiplexing, and orbital angular momentum (OAM) of vortex beams offers a new degree of freedom to increase free‑space capacity. The study demonstrates independent collinear OAM channel generation, transmission, and simultaneous detection using Dammann optical vortex gratings (DOVGs). Dammann gratings generate, transmit, and detect OAM beams to enable multiplexing. The DOVG‑enabled OAM multiplexing achieved 80–160 Tbit s⁻¹ capacity with 1600 individually modulated QPSK/16‑QAM channels across 10 OAM states, 80 wavelengths, and two polarizations, removing the bottleneck of massive OAM state detection and potentially scaling to Pbit s⁻¹.

Abstract

Data transmission rates in optical communication systems are approaching the limits of conventional multiplexing methods. Orbital angular momentum (OAM) in optical vortex beams offers a new degree of freedom and the potential to increase the capacity of free-space optical communication systems, with OAM beams acting as information carriers for OAM division multiplexing (OAM-DM). We demonstrate independent collinear OAM channel generation, transmission and simultaneous detection using Dammann optical vortex gratings (DOVGs). We achieve 80/160 Tbit s−1 capacity with uniform power distributions along all channels, with 1600 individually modulated quadrature phase-shift keying (QPSK)/16-QAM data channels multiplexed by 10 OAM states, 80 wavelengths and two polarizations. DOVG-enabled OAM multiplexing technology removes the bottleneck of massive OAM state parallel detection and offers an opportunity to raise optical communication systems capacity to Pbit s−1 level. Dammann gratings are used to realize multiplexing based on the generation, transmission and detection of optical angular momentum (OAM). The OAM of optical vortex beams offers a new degree of freedom for multiplexing and hence the promise of higher data communication rates, but massive parallel detection of OAM states has proved challenging. Now, researchers in China, Australia and Singapore have used Dammann optical vortex gratings (DOVGs) to realize multiplexing of massive OAM channels with individual modulation and simultaneous detection capabilities. They achieved a data capacity of 80 Tbit s−1 by multiplexing 1600 channels using ten OAM states, 80 wavelengths and two polarizations. This DOVG-enabled OAM multiplexing technology removes the bottleneck of massive parallel detection of OAM states and has the potential to increase optical communication capacities to the Pbit s−1 level.