Lasers are recognised for the monochromatic mother nature of their gentle, so a great deal so that you might in no way have considered there could be these kinds of a issue as a white laser. But in the unusual environment of physics, a whole lot of matters that feel extremely hard are not seriously, as demonstrated by this dust-cheap supercontinuum laser.
Of course, we’re not gurus on lasers, and definitely not on non-linear optics, so we’ll rely on [Les Wright]’s movie down below to explain what is likely on here. In essence, a “supercontinuum” is just the conversion of a monochromatic source to a broader spectral bandwidth. It is a non-linear optical system that is commonly attained with high-priced bits of kit, like photonic crystal fibers, which are optical fibers with an array of very small air-loaded holes functioning down their lengths. Blast a high-intensity monochromatic laser down one particular stop, and white light-weight comes out the other close.
These kinds of fibers are clearly fantastically costly, so [Les] seemed back in the literature and discovered that a straightforward silica glass solitary-method fiber could be applied to deliver a supercontinuum. As luck would have it, he had been experimenting with telecom fibers not long ago, so alongside with a nitrogen laser he recovered from a Dumpster, he experienced quite a great deal everything he desired. The ultimate setup uses the UV laser to pump a stilbene dye laser, which shoots a potent pulse of 426 nanometer mild into about 200 meters of fiber, and makes a attractive supercontinuum made up of light from 430 nm to 670 nm — really significantly the entire seen spectrum.
It is fantastic to see tasks like this that leverage reduced-value, uncomplicated-to-resource devices to examine esoteric physics concepts.