Researchers wirelessly transmit power over 98 feet of thin air : ScienceAlert

Thanks to newly developed technology, one day we will be able to wirelessly charge mobile phones and tablets in the air.

The researchers used infrared laser light to transmit 400mW of optical power at distances of up to 30 meters (98 feet). That’s enough to charge a small sensor, but it could eventually be developed to charge larger devices such as smartphones as well.

All this is done in a completely secure way. The laser reverts to low power mode when not in use.

The technical term for it is distributed laser charging, and the specific type developed here is safer and can go further than previous experiments with similar kinds of wireless power transfer technology.

“Most other approaches require the receiving device to be in a special charging cradle or fixed, but with distributed laser charging, as long as the transmitter and receiver are within line of sight of each other, the tracking process self-alignment is possible without Jinyong Ha, an electrical engineer at Sejong University in South Korea.

Laser transmitter and receiver on the table
Experimental device. (Ha Jin Young, Sejong University)

Components that typically reflect light are laser cavity Together they will be the same device. Here it is separated into transmitter and receiver. In other words, as long as the transmitter and receiver can see each other, a laser cavity forms in the space between them.

In the experimental setup, an amplifier transmitter specially treated with a silvery-white metal called erbium was placed 30 meters from the receiver and equipped with a photocell that converted the light signal into electrical power.

At just 10 mm x 10 mm (0.4 inch x 0.4 inch), this receiver is small enough to fit into compact gadgets such as sensors. For example, small smart home devices such as motion sensors and temperature sensors can be wirelessly charged this way.

I walked into the airport one day and was able to charge my phone while it was in use. No cables or plugs required. But before that, the team needs to expand the level of energy the system can transfer.

Part of that process could include upgrading the receiver’s solar cells to be able to convert more laser light into electricity. Another potential improvement would be to make the setup work with multiple receivers at once.

Lasers with a center wavelength of 1550 nanometers are in the safest part of the infrared spectrum and do not harm human skin or eyes. Scientists have made many more improvements to improve the system’s efficiency and ensure that as much energy as possible is transferred.

“The receiver unit incorporates a spherical ball lens retroreflector to facilitate 360-degree transmitter-receiver alignment, which maximizes power transfer efficiency,” Ha said. says Mr.

“The overall performance of the system depends on the refractive index of the ball lens, and we have experimentally observed that a refractive index of 2.003 is the most effective.”

Although the technology is still in its infancy, personal electronics aren’t the only areas where wireless energy transfer can prove beneficial. It can also make a big difference in industrial environments where cabling is difficult to assemble and maintain.

“Replacing factory power cords with a laser charging system saves maintenance and replacement costs,” Ha says.

“This can be particularly useful in harsh environments where electrical connections can cause interference or pose a fire hazard.”

This research Optics Express.

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