Phased Array Antenna Beam-Steering in a Dispersion-Engineered Few-Mode Fiber

We present, for the first time to our knowledge, experimental demonstration of tunable optical beamforming for phased array antennas using a few-mode fiber. The double-clad step-index few-mode fiber is dispersion engineered such that it operates as a continuously tunable 5-sample true-time delay line, enabling continuous steering of the beam-pointing angle. Using this approach, we measure the radiation pattern from 5 elements of an in-house fabricated 8-element phased array antenna at the radiofrequency of 26 GHz and demonstrate continuous beam-steering over a 59$<^>\circ$ range by sweeping the optical wavelength from 1543 nm up to 1560 nm. Such a few-mode fiber-based beamformer could be beneficial to next-generation fiber-wireless communications and radar systems, as it provides further versatility and capacity along with reduced size, weight and power consumption.