Dynamic RF Beam Steering Using Photo-Induced Fresnel Zone Plates on Solar Cells

Optically reconfigurable beam steering at millimeter-wave (mm-wave) frequencies requires engineered semiconductor surfaces with high-power optical sources. This article presents the first demonstration of beam steering using a commercially available monocrystalline silicon solar cell, directly exploiting its intrinsic photovoltaic properties for electromagnetic wave modulation. Dynamically reconfigurable Fresnel zone plate (FZP) patterns are projected onto the solar cell with low-power visible light (0.043 W/cm²), enabling reconfigurable beam steering across the Ka-band (26.4-40 GHz). The solar cell's back-contact design preserves RF transparency while providing polarization isolation up to -25 dB, and measurements show 10-dB modulation depth under illumination. Simulations and experiments confirm diffraction-based steering of a 30-GHz source. Furthermore, a 5G new radio (NR) data-link experiment at 28.03 GHz using 256-QAM modulation demonstrates the system's capability to sustain high-rate communication links. This fabrication-free and accessible approach establishes a practical path toward reconfigurable mm-wave beam steering and adaptive RF devices.