The optical fiber in the photo above doesn't just guide the beam--the fiber produces the beam. Instead of a tube of helium and neon gas, or a piece of ruby, the "active medium" of this laser is added to the glass in the fiber. Since the mirrors are just the polished ends of the fiber, there is nothing to go out of alignment, and maintenance is easy.
- Fiber lasers are using laser cutting. - To find out how the fiber optic laser promises to fuse the technologies of transistors and fiber optics, see this Penn State page. Also, here's another image of a fiber laser. - To see how the fiber contains a laser beam, visit The Physics Classroom: Total Internal Reflection.
