Fiber Lasers
Fiber lasers are lasers which use the core of an optical fiber as the gain medium to generate and deliver a laser beam. Gain medium consists of a fiber inner core doped with rare earth ions such as erbium, neodymium, ytterbium, thulium or praseodymium. Most fiber lasers use diode bars as energy sources. Typically radiation produced by diode bars is injected into a cladding that surrounds the “active” inner core. To contain this radiation, the fiber (inner core plus cladding) is covered with an outer sheath that has a lower refractive index, thus preventing radiation to escape due to total internal reflection. This way, the confined radiation produced by diode bars bounces around inside the fiber and every time it crosses the core, energy builds up and excited atoms emit photons, producing the laser beam.


Schematic diagram of high power fiber laser using_a_double-clad_fiberSchematic diagram of Core and Clad of fiber laser