Predmet ove disertacije jeste razvoj detaljnih i efikasnih numeričkih i analitičkih modela poluprovodničkih optičkih pojačivača, za primrnu u pristupnim optičkim mrežeme...
The object of the dissertation is the development of various detailed and efficient numerical and analytical models of semiconductor optical amplifiers, employed in access optical networks. Starting from the optical properties of active
regions based on the bulk semiconductor and the multiple quantum wells, the
theoretical model of the two most commonly used amplier types traveling-wave
and reective, is developed, such that the ampliers are optimized to be polarization
insensitive. The models are based on a system of integro-dierential equations,
written with respect to carrier densities, spectral photon densities of the signals and
noise, and signals' phases for both propagation directions.
First o, a wideband steady-state amplier model is developed, together with the
accompanying numerical algorithm, further used for a detailed amplier analysis.
It has been shown that the reective amplier exhibits pronounced resonances and
antiresonances in the spectrum of the output amplied spontan...eous emission noise.
The transmission gain of the reective ampliers proves to be higher in comparison
to the traveling-wave ones. Results show that spectrally dependent connement
factor and refractive index variation signicantly inuence the transmission gain.
Relying on a set of appropriately chosen approximations, a new, semi-analytical
model is developed, together with the algorithm for its implementation. Semianalytical
model provides reliable results within the time that is up to two orders
of magnitude shorter in comparison with the wideband steady-state model, which
makes it an attractive choice for software solutions intended for modeling of complex
optical communication systems.
Dynamic analysis starts with the large signal numerical model, implemented
using the ½up-wind scheme for equation solving. It has been shown that both
amplier types can be successfully used in electro-optic signal (re)modulation. Dynamic
characteristics are further studied using a detailed small-signal model with the
current modeled as a traveling microwave. Results reveal that reective ampliers
exhibit two maxima in −3dB bandwidth dependence on input optical power, which
is not the case with their traveling-wave counterparts. Finally, analytical formulae
for −3dB bandwidth of both amplier types are developed, for a commonly chosen
transparency operating regime, which show excellent qualitative agreement with the
results obtained using the numerical model.
Based on the obtained results, guidelines are provided for the choice of operating
regime, geometrical and structural amplier parameters, for increasing the
transmission gain and the modulation bandwidth.
Faculty:
University of Belgrade, School of Electrical Engineering
