Mousumi Basu
Indian Institute of Engineering Science & Technology, India
Title: Nonlinear pulse dynamics in passive and active optical fibers
Biography
Biography: Mousumi Basu
Abstract
Propagation of optical pulses with different shapes in optical fibers has created tremendous research interests because of the potential applications in ultra high speed optical systems, quantum optics, high power lasers, supercontinuum generation. Nonlinear pulse reshaping towards Parabolic (PP), semi parabolic (SPP) and triangular (TP) pulses can be possible in optical fibers and it depends on fiber parameters such as dispersion, nonlinearity and gain; and also on pulse properties such as pulse energy, width and peak power. A Gaussian pulse propagating through a normal dispersion fiber amplifier, can be changed to a linearly chirped PP of self similar nature in presence of nonlinearity and thus it does not suffer from the deadly effects of optical wave breaking. Any pulse from a CW laser asymptotically converts into a PP independent of its initial shape when Raman fiber amplifier is used to provide gain. However use of erbium doped fiber amplifier (EDFA) may change the dynamics of pulse propagation. For EDFA the dipole relaxation time and gain dispersion term control the pulse propagation by modifying the nonlinear Schrödinger equation. It is also seen that the evolved pulse may be parabolic or nonparabolic; depending on the repetition rate of the input laser source, initial pulse parameters as well as fiber parameters. Some nonparabolic pulses are very close to PP, which are termed as semiparabolic pulse. Those SPP can be again stabilized to PP using two stage fiber system. At the same time prechirping technique in a normal dispersion fiber is also helpful to generate stable TP which are used as sawtooth pulses in optical signal processing.
