Researchers have demonstrated, for the first time, that laser light can be used to manipulate a glass optical fiber tapered to a sharp point smaller than a speck of dust, in the middle of an optical fiber with a hollow core. Amazingly, optical forces cause the sharp point, or “nanospike,” to self-align at the center of the hollow core, trapping it more and more strongly at the core center as the laser power increases.”Launching very high power laser light into an optical fiber, especially a hollow-core fiber, can be very difficult and usually requires extensive electronics and optics to maintain alignment,” explained Philip Russell, director at the Max Planck Institute for the Science of Light in Erlangen, Germany, and leader of the research team. “This can be accomplished with our new system by simply pushing the nanospike into the hollow core and then turning up the laser power slowly. Once the nanospike self-stabilizes, you can turn up the laser power and nothing will move or get damaged.”In The Optical Society”s high impact journal Optica, the researchers report that almost 90 percent of the laser light was transferred from the nanospike to the hollow-core fiber. The new work could increase applications for hollow-core fibers, a new class of fiber that features a hollow core rather than one made of glass like traditional optical fibers. Hollow-core fibers are especially good at handling high-power lasers, making them potentially useful for laser machining and cutting of metals, plastics, wood and other materials.
