Authors: Á. Valera-Albacete, E. Castillo-García, F. Almonacid, E. F. Fernández  ·  AdPVTech / CEACTEMA, University of Jaén, Spain  ·  Funded by EIC Pathfinder  

Imagine charging a drone mid-flight, or powering a remote sensor kilometres away, without a single wire. That is the promise of Wireless Laser Power Transmission (WLPT): a laser fires a beam of light; a photovoltaic receiver catches it and turns it back into electricity. The concept is elegant, but taming the physics of Gaussian laser beams — whose intensity peaks sharply in the centre and fades at the edges — has proven devilishly hard for receiver designers. A new paper from researchers at the University of Jaén tackles one of the technology's most stubborn practical obstacles — and offers a surprisingly elegant solution. 

The problem with laser beams 

Unlike sunlight, a laser beam is far from uniform. Its intensity peaks sharply at the centre and fades toward the edges, which means that when multiple solar cells share the same receiver, they end up absorbing very different amounts of light. Wire those mismatched cells together the conventional way and the weakest link bottlenecks the whole array, wasting a large fraction of the harvested energy before it ever reaches the load. 

A smarter way to connect the cells 

The Jaén team built a compact nine-cell silicon receiver equipped with custom concentrator optics and tested it under a real 808 nm laser beam. Rather than connecting all cells in a simple series or parallel layout, they grouped them according to the amount of light — and therefore current — each one naturally receives. Cells near the bright centre form one group; those in the middle ring another; the dim corner cells a third. Each group then feeds its own power-tracking circuit. 

"Grouping cells by photocurrent brings the module's response close to the theoretical ideal, even under strongly non-uniform illumination." 

The results, published in Optics & Laser Technology, show this current-based grouping dramatically outperforms conventional wiring schemes and nearly matches a theoretically perfect, mismatch-free receiver. The concentrator optics also proved their worth on a second front: the receiver maintained high efficiency for beam angles well beyond what bare photovoltaic converters can tolerate — a critical advantage whenever pointing is imperfect. 

Why it matters 

WLPT is attracting growing interest for powering drones, remote sensors, underwater platforms, and space systems — anywhere that cables are impractical and radio-frequency transfer falls short. The findings from this study apply broadly: the interconnection principles demonstrated here are largely independent of the photovoltaic material used, meaning they could be carried over to the high-efficiency III–V semiconductor devices that push WLPT performance to its limits. 

The full paper, including detailed optical, thermal, and electrical measurements, is freely available via the link.