Fiber lasers use a small optical fiber made out of silica glass. The most common fiber laser is the Erbium- Doped Fiber Laser. Doping, is when small particles of one element are mixed with another. Erbium is a very absorbent and can produce a wavelength of 970 Nano meters. The doped fiber is located inside the fiber core. An advantage to using fiber lasers are their superior stability. They do not bounce between mirrors. They produce a straight beam and are finely aligned. Because the beam is confined, it has a small core. It produces a very small high powered beam dot. Fiber lasers, like other lasers, need to be cooled down with a cooling jacket. They are economical and energy efficient, converting about 75% of its power to the pump source.