Researchers from the University of Strathclyde, led by Othman Younus and Harald Haas, have developed a novel approach to integrate energy harvesting with high-speed optical wireless communication. This work, published in the journal Nature Communications, aims to address the growing demand for energy-efficient wireless communication systems, particularly for Internet of Things (IoT) devices.
The team has created multi-segment photonic power converters (PPCs) based on gallium arsenide (GaAs), which serve dual purposes: harvesting energy and detecting high-speed optical data. GaAs-based PPCs offer six times greater electron mobility than silicon- or cadmium telluride-based cells, enabling faster data detection and improved power efficiency. However, the bandwidth of these devices is typically constrained by junction capacitance, which increases with the active area, creating a trade-off between power output and data rate.
To overcome this limitation, the researchers segmented the active area of the PPCs into 2, 4, or 6 subcells, forming circular areas with diameters of 1, 1.5, or 2.08 millimeters. This segmentation reduces capacitance and boosts bandwidth while preserving light collection. The subcells were fabricated on a semi-insulating GaAs substrate with etched trenches for electrical isolation, optimizing absorption and minimizing parasitic effects.
The team tested the PPCs in an eye-safe 1.5-meter optical wireless link, employing orthogonal frequency-division multiplexing (OFDM) with adaptive bit and power loading. The system achieved a record data rate of 3.8 gigabits per second (Gbps), four times higher than previous works. Additionally, the system converted 39.7 percent of optical power from a beam of 2.3 milliwatts. While the segmentation increases the sensitivity of the alignment, the findings provide new solutions for off-grid backhaul for future communication networks, such as 6th generation (6G) cellular.
For the energy sector, this research offers a promising avenue for integrating energy harvesting with high-speed data communication, which could be particularly useful for remote or off-grid energy systems. By eliminating the need for charging or battery replacements, these PPCs could enhance the efficiency and reliability of energy systems, particularly in applications where continuous power supply is crucial.
This article is based on research available at arXiv.