Wireless charging is already currentcell phoneand a feature of other devices, but it’s not much better functionally than plugging in the power cord. The device usually needs to sit on a base or make contact with a special surface and not move too far while charging.
In order to exert the ability of wireless charging, it is necessary to break through the limitation of transmission distance and realize the seamless transmission of power like Wi-Fi transmission of data. Scientists are working toward that goal, trying to transmit microwaves or lasers to devices, or to generate electromagnetic fields that fill a room, but it often requires bulky and complex equipment.
For the new study, scientists at Sejong University developed a new wireless charging system that uses infrared light to enable long-distance power transfer. It consists of two main parts – a transmitter that can be installed in the room, and a receiver that can be integrated into the electronics. The transmitter is an optical power source using an erbium-doped fiber amplifier that produces an infrared beam with a center wavelength of 1,550 nanometers (nm).
This beam is then launched through the air to a receiver, which consists of a spherical lens retroreflector. This focuses incoming light to a point in the center, where a photovoltaic cell waits to absorb the light and generate electricity. If the line of sight between the transmitter and receiver is interrupted, the device quickly and automatically switches to a low-intensity safe mode.
In tests, the team was able to transmit a 400-milliwatt beam over a distance of 100 feet, where a 10-by-10-millimeter (0.4-inch) receiver converted it into 85 milliwatts of electricity. That’s not a lot of energy — maybe enough to power a small sensor or two — but the team says it could scale to the point of charging everyday electronics like cell phones. Systems that work on a similar principle are being tested on larger grid scales to replace power lines.