الفهرس Only 14 pages are availabe for public view
 |  | from | 229 |  |  |
| | | from | 229 | | |
Abstract
The inhomogeneous broadening, although secondary to homogeneous
broadening in Erbium doped fiber amplifier, recent experimental results show its
effect in some applications. Laser stabilization techniques are essential for the
applications of Erbium doped fiber amplifiers in WDM systems. One such important
configuration is obtained by inducing laser oscillations in the amplifier. To treat this
system we developed a full mathematical model based on semiclassical theory. The
Er ions are described by the density matrix approach taking into consideration the
Stark splitted manifolds of each energy level. However, the electromagnetic field is
described classically. Monochromatic as well as polychromatic field are considered.
Special attention has been given to an laser oscillation with high power levels inside
the amplifier. This model is applied to our case by extracting the relevant parameters
from experimental results. The model describes the saturation effects due to the signal
powers not only on the population difference of the amplifying levels but also on the
concerned on the emission and absorption themselves. The model can also handle
beating effects between the propagating signals as well as lending itself for describing
fast field variations. The only basic assumption on the model is the thermalization of
the population of the Stark splitted sup-levels which makes this model valid for power
variation up to 100 GHz. This model is then applied to the laser stabilized Erbium
doped fiber amplifier appropriate approximation particularly of Erbium doped fiber
systems makes it possible to reduced the computation effect will allowing an
approximate analytical solution. It is found that the analytical solution in within 5%
error from the numerical solution. The effect of fiber length, mirror reflectivity, pump
wavelength, laser wavelength, and the Er3+ concentration on threshold pump power
are discussed. Gain control under add/DROP ten channels in wave division multiplexing
transmission has been calculated for different system parameters, particularly the laser
wavelength. This last parameters show sensitively to inhomogeneous broadening
particularly 1.53 mm wavelength. The results show that there exist a preferred set of
parameters that yield the best gain control and noise figure for the amplifier. The gain
excursion of less then 0.3 dB found when nine out of ten channels were DROPped