Laser Power Beaming: A Breakthrough in Wireless Energy Transfer
The U.S. military is pushing the boundaries of wireless power transmission, and recent advancements suggest a future where energy can be beamed across notable distances. A team led by Paul Jaffe, Principal and Head of the College of Science and engineering at the University of Glasgow, recently achieved a record-breaking milestone in laser power beaming - a critical step toward realizing DARPA’s ambitious POWER (Persistent optical Wireless Energy Relay) program. But what makes laser technology so promising, and what challenges remain? Let’s delve into the details.
Why Lasers for Wireless Power?
For decades, radio waves have been the go-to for wireless communication. Though, when it comes to power transmission, lasers offer distinct advantages.As Jaffe explains, lasers are far more focusable than radio waves. You can create a narrow, concentrated beam with minimal spreading – a crucial factor for efficient long-distance energy transfer.
Here’s a breakdown of the key differences:
Focusability: Lasers create highly concentrated beams. Radio waves spread out more rapidly.
Antenna Size: Laser systems require considerably smaller equipment than radio counterparts. A previous microwave test at the Naval Research Laboratory required a 5-meter transmitter and 2-meter receiver to transmit 1.6 kW over 1 km.
Beamforming: Radio waves,with their longer wavelengths,are harder to shape into focused beams.
However, lasers aren’t a perfect solution. Atmospheric conditions like fog and clouds can scatter optical frequencies, making microwaves generally more reliable for transmission through the atmosphere.
The Science Behind the beam
The ability to focus a beam hinges on wavelength. According to Dr. yeatman, the output diameter of any transmission needs to be much larger than the wavelength to achieve focus.
Infrared light (used in laser power beaming) has shorter wavelengths than radio waves.
Shorter wavelengths make creating a tightly focused beam significantly easier.
This precision, combined with the potential for long-range transmission and compact equipment, makes laser technology ideal for building an airborne power relay network – the core goal of DARPA’s POWER program. In fact, jaffe states, “If it doesn’t work with optical, it doesn’t work at all [for DARPA’s goal].”
A Record-Breaking Achievement & Unexpected Discoveries
The recent record, achieved at the High Energy Laser Systems Test Facility in New Mexico, wasn’t even the primary objective of the team. This highlights the exploratory nature of the research and the potential for unforeseen breakthroughs.
Beyond the record itself, the project yielded several surprising discoveries:
Diffractive Optics: Traditionally, mirrors and lenses are used to redirect laser beams. The team found that diffractive optics - which manipulate light using patterns of microscopic structures - are exceptionally well-suited for this application, particularly due to their efficiency with monochromatic wavelengths.
Additive Manufacturing & Integrated Cooling: The growth of additively manufactured optics with an integrated cooling system was another unexpected success. This innovation opens up “new and intriguing ways to tackle some of the problems that are very likely to have applications far beyond what we’re doing for POWER,” Jaffe notes.
What does This mean for the Future?
The advancements in laser power beaming represent a significant leap forward in wireless energy transfer. While challenges remain – particularly regarding atmospheric interference – the potential benefits are considerable. Imagine a future with:
Persistent drone operation: Airborne relays could provide continuous power to drones, extending their flight times and capabilities.
Remote power delivery: Energy could be beamed to disaster areas or remote locations without the need for customary infrastructure.
Space-based solar power: Collecting solar energy in space and beaming it down to Earth could provide a clean and lasting energy source.
This isn’t just a theoretical exercise. The U.S. Army’s accomplished demonstration, coupled with ongoing research, is paving the way for a future powered by light. as Yeatman aptly puts it, the recent achievement was “an notable achievement” – a testament to the ingenuity and dedication of the POWER team and a glimpse into the exciting possibilities of wireless power beaming.
**(Image: Paul Jaffe (in orange) stands with the POWER Receiver Array Demo team around the receiver after achieving a new
