Multi-Segment Photonic Power Converters for Energy Harvesting and High-Speed Optical Wireless Communication

The demand for energy-efficient high-speed wireless communication, coupled with the rapid rise of IoT devices, requires systems that integrate power harvesting with optical data reception to eliminate the need for charging or battery replacements. Recent advances have explored the use of solar cells as optical receivers for high-speed data detection alongside power harvesting. GaAs-based Photonic power converters (PPCs) provide six times greater electron mobility than silicon- or cadmium telluride-based cells, enabling faster data detection and improved power efficiency. However, their bandwidth is constrained by junction capacitance, which increases with active area, creating a trade-off between power output and data rate. To address this, we propose and test multi-segment GaAs-based PPCs that serve as both energy harvesters and data detectors. By segmenting the active area into 2, 4, or 6 subcells, forming circular areas with diameters of 1, 1.5, or 2.08 mm, we reduce capacitance and boost bandwidth while preserving light collection. Fabricated on a semi-insulating Gallium arsenide (GaAs) substrate with etched trenches for electrical isolation, the series-connected subcells optimize absorption and minimize parasitic effects. The PPCs were used for an eye-safe 1.5 m optical wireless link, employing Orthogonal frequency-division multiplexing (OFDM) with adaptive bit and power loading. The system achieved a world record data rate of 3.8 Gbps, which is four times higher than prior works. The system converts 39.7% of optical power from a beam of 2.3 mW, although the segmentation increases the sensitivity of the alignment. These findings provide new solutions for off-grid backhaul for future communication networks, such as 6th generation (6 G) cellular.