You may soon be swapping your standard phone charger for a light-powered optical fiber. Researchers at the University of Ottawa found that electronic devices, including smartphones, can be connected and powered simultaneously over long distances with a simple optical fiber. Using this technology, devices can operate through extreme weather and still catch a signal in remote areas by using laser-powered solutions integrated into existing fiber optic networks. This could reduce costs and improve reliability across telecommunication networks. The researchers developed a simulation model for multijunction photonic power converters operating at infrared wavelengths used in telecommunications. These systems benefit from low attenuation losses per kilometer in fiber. “Multijunction” means the devices are constructed by stacking multiple semiconductor junctions that absorb light, resulting in more of the total laser light being converted to electric power and enabling higher voltages to be reached. Such multijunction cells have greater wavelength sensitivity than single-junction devices due to the challenge of current matching. A major component of the project involves power-by-light systems, which transmit laser light to a photonic power converter (PPC), sometimes called a laser power converter. PPCs are photovoltaic cells that convert monochromatic light into power and produce the operating voltages needed to run electrical devices. In PPCs, output voltage and efficiency are lost within the optical fiber transmission window of 1.3- to 1.6-μm laser wavelengths. Based on their research, the team developed a high-efficiency multijunction PPC to fast-track the future of connectivity. Hand with scissors courtesy of iStock.com/AnnaSivak. Phone courtesy of iStock.com/kadirkaba. “In traditional power-over-fiber systems, most of the laser light is lost,” said professor Karin Hinzer of the University of Ottawa’s SUNLAB, which collaborated with Germany’s Fraunhofer Institute for Solar Energy Systems ISE on the study. “With these new devices, the fiber can be much longer.” It is important to remember that maximizing optical-to-electrical power conversion efficiency is crucial when designing PPCs. Tuning the laser wavelength and the bandgap of the PPC’s absorber material can minimize thermalization, transparency, and current collection losses. For long-distance power transmission through optical fibers, laser wavelengths within 1.3 to 1.6 μm minimize attenuation losses. Since the bandgap-voltage offset is effectively constant with bandgap for indium gallium arsenide phosphide (InGaAsP) photovoltaic devices (bandgap of 0.736 to 1.215 eV), higher efficiencies can be achieved with larger bandgap absorber layers. Researchers created a four-junction PPC with InGaAsP absorber layers that surpassed the 50% efficiency barrier at 1.446 μm. The researchers used a calibrated drift-diffusion model that includes luminescent coupling, optical interference effects, and realistic charge transport, which provides more accurate predictions at the cost of increased computational expense. To accelerate the incorporation of power-by-light systems into telecommunication infrastructure, it is necessary to use the same fiber for simultaneous power and data transmission. However, this dual-use fiber configuration requires different wavelengths to avoid sacrificing data quality. Ten-junction PPCs were grown by metal-organic vapor-phase epitaxy (crystalline structures) and fabricated by the Fraunhofer team. So, what are the applications of this technology? Surprisingly, it can be implemented in many different fields. You may see it used in smart-grid and lightning-proof wind-turbine blade monitoring; spark-free fuel gauges in planes; remote video camera links; underwater sensors; and even in space, to power drones, satellites, and lunar vehicles.