Ph.D Thesis

Ph.D StudentBilenca Alberto
SubjectGain and Noise Properties of Semiconductor Optical
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Gad Eisenstein


This Ph. D. research addresses several aspects of gain and noise in nonlinear semiconductor optical amplifiers (SOAs). The first part of this research presents the first experimental realization of InAs / InP quantum-dash SOAs operating at 1550 nm. The unique properties of these amplifiers are highlighted in the context of high-speed wavelength direction-independent conversation and wideband all-optical nonlinear signal processing.

The second part describes a rigorous analytical analysis of the noise properties of nonlinear self-assembled quantum-dot SOAs. A new quantum-dot SOA model considering both incoherent and coherent gain phenomena is formulated. The impact of gain inhomogeneity and fast gain dynamics on the output optical noise and relative-intensity-noise (RIN) spectra is emphasized. It is shown that incoherent and wide coherent spectral holes are burned in the output optical noise and RIN spectra, thus having numerous implications in all-optical signal processing applications. Furthermore, our analysis successfully explains, for the first time, the optical noise / gain compression spectra dependence on the injected power as observed in experimental data of self-assembled nano-structure SOAs.

The last part of this research addresses the fundamental problem of the statistical properties of nonlinearly amplified isolated optical pulses in SOAs using the Fokker-Planck approach. A class of analytical / numerical solutions of the Fokker-Planck equation, as well as importance sampling simulations of the corresponding Langevin equation are described. It is proven, for the first time, that the electric field samples at the output of a moderately / deeply saturated SOA do not comprise a Gaussian process.