High-capacity millimetre-wave communications with orbital angular momentum multiplexing.

Area of Science:

• Electromagnetic wave propagation
• Wireless communication technologies
• Optical physics

Background:

• Orbital angular momentum (OAM) is a property of electromagnetic waves enabling phase front twisting.
• OAM multiplexing allows multiple coaxial data streams, potentially increasing system capacity and spectral efficiency.
• Millimetre-wave (mmWave) frequencies offer large bandwidths for high-speed communication.

Purpose of the Study:

• To demonstrate the feasibility of OAM multiplexing for enhancing mmWave wireless communication links.
• To investigate the potential of OAM beams for increasing spectral efficiency and system capacity.
• To develop and test an OAM mode demultiplexer for practical application.

Main Methods:

• Utilizing four independent orbital angular momentum beams on each of two polarizations for multiplexing.
• Establishing a 32-Gbit s(-1) mmWave link over a 2.5-meter distance.
• Developing a mmWave OAM mode demultiplexer capable of separating multiple OAM channels.

Main Results:

• Achieved a spectral efficiency of approximately 16 bit s(-1) Hz(-1) using eight OAM channels (four per polarization).
• Recovered all eight OAM channels with bit-error rates below 3.8 × 10(-3).
• Demonstrated an OAM mode demultiplexer with crosstalk less than -12.5 dB for four OAM channels.

Conclusions:

• Orbital angular momentum multiplexing is a viable technique for significantly improving mmWave wireless communication capacity and spectral efficiency.
• The demonstrated OAM multiplexing and demultiplexing technologies pave the way for next-generation high-speed wireless systems.
• Successful recovery of multiple OAM channels with low bit-error rates validates the potential of this approach for practical deployment.