Influence of Gain Dispersion on the Propagation Characteristics of Ultrashort Optical Pulses in Distributed Fiber Amplifiers

The physical model for the optical pulse propagating in the amplifier has been established. Within the normal dispersion region of the fiber, the evolution of the optical pulse in the amplifier has been simulated numerically, and the influence of gain dispersion on the propagation characteristics of the pulse has been discussed emphatically. The results show that, during the propagation of the ultrashort optical pulse in a distributed fiber amplifier, group velocity dispersion and Kerr nonlinear effect will affect the pulse profile and spectrum. For the ultrashort optical pulse with a wideband spectrum, the influence of gain spectrum on the propagation characteristics of the optical pulse, in essence, is that of gain dispersion, which is equivalent to a loss mechanism and will generate gain narrowing effect, so it should be considered in the design of an amplifier system.