Two-Dimensional Fiber Beamforming System Based on Mode Diversity

• Published in: IEEE access Vol. 9; p. 1
• Main Authors: Zhang, Meiling, Liu, Xiao, Pang, Rui, Hu, Guijun
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.01.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Array signal processing; Beamforming; Coupled modes; Coupling; Delay lines; Delays; few-mode fiber; Laser beams; mode division multiplexing; Optical fiber dispersion; Optical fibers; optical true time-delay; Performance evaluation; Scanning; Time lag; Two dimensional displays
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3062670

In this paper, a novel two-dimensional (2D) beamforming system based on mode diversity and true-time delay (TTD) of optical fiber is proposed. The system is composed of two cascaded TTD units, which are single-mode fiber TTD line array and mode TTD line array of few-mode fiber. For the first time, the mode diversity technology is applied to the 2D beamforming system which can realize beam scanning at a single wavelength and greatly reduces the cost and complexity. A beamforming system with 3×3 array antenna is built, and the properties of which are experimentally evaluated under a single wavelength of 1550.52 nm. The azimuth and elevation angles can reach the scanning range of ±60°. The gain performance are characterized, which decreases about 6 dB when the angle changes from (0.11°, -0.11°) to (59.82°,60.21°) or (-59.25°, -60.02°). The influence of frequency and mode coupling on the system performance are evaluated. The beam direction of the system is independent of microwave signal frequency while the test scope is 8.5 GHz to 11.5 GHz. Mode coupling has no effect on the beam direction of the system.