New kind of laser uses small particle clumps to generate light

Lasers usually use mirrors to create laser light, but a new kind uses clumps of moving particles. The result is a laser that is more programmable and could generate extra sharp visual displays

Physics


July 14, 2022

Laser beams cross in different directions from several different sources

A new kind of laser is more programmable than conventional ones

Getty Images / Flavio Coelho

A new kind of laser uses small moving particles to produce light rays. The laser is more programmable than standard lasers, and the approach could be used to create visual displays that are sharp from all angles.

Conventional lasers repeatedly reflect light between two mirrors until it becomes bright and focused. Riccardo Sapienza at Imperial College London and his colleagues have built a laser that uses particles that can arrange themselves to perform a similar process.

The new type of laser first requires the use of green light from a traditional laser. The researchers throw this green light into a small glass box filled with a liquid solution containing titanium oxide and silicone oxide particles. This heats up the silicone oxide particles and causes the titanium oxide particles to clump around them.

The green light then bounces between particles in the lump – in the same way that light bounces between mirrors in conventional lasers – until the lump itself begins to emit a laser beam, now in the color red.

By pushing the particles into different positions with the green light, the team can program the properties of the light emitted by the laser, such as where in the device it originates from and how pure its color is. By comparison, conventional lasers cannot be adjusted after manufacture.

Diederik Wiersma at the University of Florence in Italy says that the new laser is the first kind that can be programmed by moving its components, allowing it to have more functions.

Sapienza says a use can be in display screens, such as digital billboards. Particles could move and gather in a specific place in the screen and emit a color that could be very clean, visible in both very strong and very dim light and from all lines of sight.

In the future, he wants to devise a way for particles to move independently around the solution and start emitting laser light when they encounter a pollution or other environmental change such as higher acidity. He says such a sensor would be a bit like a “living laser” that explores the surroundings and changes shape so that it can signal when it encounters something dangerous.

Journal reference: Natural physicsDOI: 10.1038 / s41567-022-01656-2

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