Mоделовање полупроводничких оптичких појачавача за примене у оптичким приступним мрежама

Abstract

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 spontaneous 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.