Fiber Gas Laser

Lasers are incredibly important to many consumer, scientific, and industrial products. The functions of these lasers can vary widely, with different lasers possessing different levels of power, wavelength, and beam quality. Ultimately, these differences translate into a host of various uses, from repairing severed neuron connections to glimpsing the structure of biomolecules.

Now, a new kind of laser has achieved a new and long-sought after spectral range. This new laser is expected to lead to the development of innovative uses for mid-infrared lasers, which are currently used in spectroscopy, environmental sensing, and detecting explosives.

The tech was developed by scientists from the University of Bath in the United Kingdom. Their findings were published in the journal Optica.

The fiber gas laser is capable of emitting a pulsed and continuous mid-infrared (IR) beam between a spectral range of 3.1 and 3.2 microns, which has posed a challenge for laser developers for a long time. It has been heralded as the "holy grail" range, due to how long scientists have been trying to achieve it.

It combines properties of both gas and fiber lasers. The researchers placed a suitable gas inside a hollow optical fiber to achieve the fiber gas laser.

William Wadsworth, co-lead on the research, explains that "beyond about 2.8 microns, conventional fiber lasers start to fall off in terms of power, and the other main technology for the mid IR, quantum cascade lasers, doesn't pick up until beyond 3.5 microns....this has left a gap that has presented a great deal of difficulty."

Silica Hollow-Core Fibers
The fiber's long and thin bubbles of glass reflect light into the fiber's core much in the same way that light reflects off the surface of the soap bubble in the foreground, making it appear iridescent. Credit: University of Bath

The success of the new laser is owed to the research team’s development of silica hollow-core fibers, which use internal glass structures to contain light in hollow cores. Traditional optical fibers do so within a solid core.

By remaining mostly inside the hollow cores, light isn’t absorbed at wavelengths over 2.8 microns like it does in silica-based glass, which is the preferred material for creating optical fibers.

"This new way to construct a gas laser could be expanded to make more and more laser types that would have been impossible without our hollow-core fiber," says Fei Yu, another member of the research team.

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