Ultrashort Laser Pulse Phenomena, 2nd Edition

Fiber Lasers 381

well into the tetravalent silica matrix, tending instead to form strongly

interacting clusters at the high concentrations necessary for practical bulk

glass lasers [146]. The confinement of both the laser and pump modes allows

the gain dopant to be distributed along greater lengths of fiber at lower con-

centration, obviating the need for high concentrations and so eliminating

the interactions cited previously.

• Diode laser pumping is practicable (due in large part to the previous two

points). Single mode laser diodes have been developed at 980 nm and

1480 nm for erbium fiber amplifiers in telecommunications applications.

The four-level structure of neodymium allows for pumping even by multi-

mode lasers, such as high-power laser diode ...