Sejong University researchers have reported in their paper, titled "Long-range wireless optical power transfer system using an EDFA" published in Optics Expres, a new system to wirelessly transmit power over 98 feet (30 meters) using infrared laser light wirelessly. The amount of electricity is enough to charge sensors, but further progress could possibly charge mobile phones in public places.

Study team leader Jinyong Ha from Sejong University in South Korea explained that the ability to power devices wirelessly could eliminate the need to use power cables for phones or tablets, Science Alert reported. More so, it could be used for monitoring processes in manufacturing plants, and power various sensors, like those in the Internet of Things (IoT) devices.

New Laser Charging System Safer and Goes Further Beyond

Researchers used infrared laser light to transmit 400mW of light power over 98 feet (30 meters) through thin air. The distributed laser charging is perfectly safe as it falls back to a lower power mode when not in use and is able to go further beyond previous experiments with similar concepts.

Furthermore, researchers explain that laser charging works like a traditional laser but is separated into a transmitter and receiver. Ha said that the distributed laser charging system enables self-alignment without the tracking processes as long as both transmitter and receiver are in the line of sight of each other.

According to the press release via Optica, the system automatically switches to a power-safe mode when there is an obstacle that cuts the line of sight between the transmitter and receiver. In this way, it promotes hazard-free power delivery in the air.

Additionally, the team used an erbium-doped fiber amplifier optical power source that has a central wavelength of 1550 nm, which is in the safest region of the wavelength range and poses no harm to human eyes or skin. Also, it creates a narrowband beam with optical power within the safety limits for free space propagation.

The team also incorporated a spherical ball lens retroreflector in the receiver to facilitate the 360-degree transmitter-receiver alignment. Ha said that they noticed that the overall performance depended on the refractive index of the ball lens, wherein the most effective is at a 2.003 reflective index.

Tesla's Vision of Wireless Power Transmission

The new technology might still be in its early days, but its possible use could already be imagined. From the wireless energy transfer to power sensors and charge electronics to making a huge difference in the industrial environment where cabling is not only hard to put together but also difficult to maintain.

According to an article on the Suffolk University website, wireless power transmission (WPT) was one of Nicola Tesla's dreams. He wanted to create a way to supply energy without using cable wires and almost accomplished it with his creation of the Tesla coil, which could wirelessly transmit electricity.

He experimented with the WPT from 1891 to 1898 using a radio frequency resonant transformer of the Tesla could that produces high voltage, high-frequency currents that could transfer power over short distances without wires.

Sadly, the Tesla coil has no practical application anymore. Nonetheless, Tesla's vision of WPT has transformed the way electricity was understood and used even to this day.

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