February 1, 2023

Lasers are identified for the monochromatic nature in their mild, such a lot in order that you could by no means have concept there may well be this sort of factor as a white laser. However within the bizarre international of physics, a large number of issues that appear inconceivable aren’t truly, as demonstrated through this dirt-cheap supercontinuum laser.

After all, we’re no longer mavens on lasers, and on no account on non-linear optics, so we’ll depend on [Les Wright]’s video under to provide an explanation for what’s occurring right here. Principally, a “supercontinuum” is solely the conversion of a monochromatic supply to a broader spectral bandwidth. It’s a non-linear optical procedure that’s normally completed with pricey bits of equipment, like photonic crystal fibers, which might be optical fibers with an array of tiny air-filled holes operating down their lengths. Blast a high-intensity monochromatic laser down one finish, and white mild comes out the opposite finish.

Such fibers are patently superbly pricey, so [Les] seemed again within the literature and located {that a} easy silica glass single-mode fiber may well be used to provide a supercontinuum. As good fortune would have it, he were experimenting with telecom fibers lately, so at the side of a nitrogen laser he recovered from a Dumpster, he had just about the whole thing he wanted. The overall setup makes use of the UV laser to pump a stilbene dye laser, which shoots a formidable pulse of 426 nanometer mild into about 200 meters of fiber, and produces a beautiful supercontinuum containing mild from 430 nm to 670 nm — just about all the visual spectrum.

It’s nice to look tasks like this that leverage low cost, easy-to-source apparatus to discover esoteric physics ideas.