Charging your smartphone with lasers? UW engineers find a way — GeekWire

Joanna Estrada
February 22, 2018

Engineers at the University of Washington have demonstrated the ability to charge a smartphone wireless from across a room using a laser. The power cell charges the smartphone by tapping the power from the laser. As the laser reaches a smartphone, special 3D printed "retroreflectors", which have been placed around the power cell on a smartphone, reflect the guard beams back to photodiodes on the laser emitter. To bleed off excess heat from the laser, the device also has a flat metal heatsink.

"Safety was our focus in designing this system", co-author Shyam Gollakota, PhD, an associate professor in the UW's Paul G. Allen School of Computer Science & Engineering, said in a statement. "We have designed, constructed and tested this laser-based charging system with a rapid-response safety mechanism, which ensures that the laser emitter will terminate the charging beam before a person comes into the path of the laser".

Majumdar said that the safety standard of the device was "robust" and up to the mark to apply it to a variety of commercial and home settings. A narrow beam can deliver a steady 2W of power to 15 square-inch area from a distance of up 14 feet.

But this can be adjusted. The emitter can also be made to project charging lasers to cover 100 sq cm over a distance of 12 metres.

The engineers responsible for the technology have said that they have put safety measures in place to be confident that the technology is not risky. The emitter can be modified to charge from up to 40-feet away and can be wide enough to charge anything placed on a counter or tabletop.

The smartphone can signal its location through the emission of high-frequency "chirps", the study explained.

However, they will not cause a disruption each time you want to charge your phone.

The laser emitter is created to automatically sense when a phone is ready to be charged, while the smartphone was programmed to send out high-frequency "chirps" inaudible to the human ear that tells the emitter where it is.

Someday charging your smartphone may be as simple as just placing it on a table or countertop.

Although wireless charging for mobile devices via induction pads has been available for some years, they still can't be charged without being relatively close to a power socket. The laser is configured to produce a focused beam in the near-infrared spectrum.

The safety system consists of a number of guard beams emitted by another laser which is co-located with the power laser and surround its beams.

The smartphone is charged by the beam through a power cell located at the back of the phone. With the technology, the charging beam is generated by a laser emitter.

The charging and guard lasers are invisible to the human eye but have been colored red for demonstration purposes. The interruption can be sensed quickly enough to detect even the fastest movements of the human body and prevent burns.

After detection, the laser begins to charge the phone battery.

This all works as quickly as the process of plugging your phone into a USB port. "But instead of plugging your phone in, you simply place it on a table".

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