ABSTRACT
A fiber laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, and thulium. This chapter discusses high-energy ultrafast fiber lasers and their applications and high-power ultrafast fiber lasers and their applications. It provides a schematic diagram of the high-energy fiber laser system by several fiber laser groups, such as PolarOnyx, Cornell University, and IMRA. In the high-power photonics crystal fiber (PCF) amplifier, first, a PCF is used to provide large mode field diameter for signal amplification in the core and large numerical aperture (NA) as high as 0.8 in the cladding for coupling more pump power into the fiber. This enables the use of a short length of fiber to increase average output power and to reduce the effect of nonlinearity for high-energy pulse.
