Optical modulation and wavelength conversion using electroabsorption modulators

Electroabsorption modulators can be used in high-speed optical communication systems for a variety of optical signal processing functions, such as optical modulation and wavelength conversion. This thesis characterizes and models electroabsorption modulators for optical modulation and wavelength conversion, and studies the implications of the properties of electroabsorption modulators on optical transmission system performance.; For optical modulation using electroabsorption modulators, the effect of the optical input power on the properties of electroabsorption modulators (electroabsorption, frequency chirp and frequency response) is experimentally characterized, the dynamics of the photogenerated carriers and its effect on the characteristics of optical modulation are explored based on the carrier rate equation, and the system performance implications of the modulator's optical input power are evaluated by both system experiments and numerical simulations. The properties of the electroabsorption modulators are found to be dependent on the optical powers; particularly, higher optical input powers lead to reduced absorption, increased α-parameter and possibly degraded frequency response. The effect of the optical input power is attributed to the photogenerated carriers. The dynamics of the photogenerated carriers is modeled with a carrier rate equation, and numerical simulations show that the photogenerated carriers affect the optical modulation. The results of numerical simulation and system experiments demonstrate that the performance of optical transmission using electroabsorption modulators degrades, or more exactly, the fiber dispersion penalty increases, with an increase in the optical input power to the modulator.; While the optical power dependence of modulator properties affects the optical modulation and transmission performance adversely, cross-absorption modulation takes advantage of absorption saturation in electroabsorption modulators to achieve all-optical wavelength conversion. Absorption saturation and static cross-absorption in electroabsorption modulators are experimentally characterized. A theoretical model based on the carrier rate equation and absorption saturation is built to predict the cross-absorption phenomenon. The cross-absorption modulation is experimentally tested and theoretically estimated; specifically, the output signal power and frequency chirp of the wavelength-converted signal are experimentally characterized and numerically simulated based on the rate equation model. The numerical simulations and the experimental measurements show good agreement for cross-absorption modulation. The noise transfer characteristics in wavelength conversion using cross-absorption modulation are experimentally evaluated. The experimental results show that the signal and noise transfer characteristics are both lowpass processes. The system performance of wavelength conversion is numerically simulated and experimentally assessed. All-optical regeneration with pulse reshaping capability is demonstrated with wavelength conversion using electroabsorption modulators.