| Abstract: | In this thesis a theoretical model of laser nonlinearity is analysed and the intermodulation noise is calculated. The large-signal-model of the laser rate equations is used in the analysis. An output-to-input approach is used to obtain a general system equation for the laser and then Volterra series expansion is applied to the system equation to obtain system transfer functions. First, the nth-order Volterra transfer functions, $G\sb{n}$($w\sb1$, ...,$w\sb{n}$), from output to input are calculated. Then, based on harmonic balance the forward Volterra transfer functions, $F\sb{n}$($w\sb1$, ...,$w\sb{n}$), are calculated from $G\sb{n}$($w\sb1$, ...,$w\sb{n}$), and these $F\sb{n}$($w\sb1$, ...,$w\sb{n}$), are used to model the frequency dependent form input-to-output nonlinearities of the laser. The theoretical models for second harmonic (2HD), third harmonic (3HD) and third-order intermodulation (IMD) distortions are expressed in terms of signal frequency, optical modulation depth and laser parameters. Using the Mircea-Sinnreich equations, intermodulation spectra are computed. Harmonic distortions and third-order intermodulation distortion for various carrier (C) levels have been computed and variations of 2HD/C, 3HD/C and IMD/C with frequency and D.C. bias are shown graphically. This system analysis are compared with previously published results and a good agreement is found. (Abstract shortened by UMI.) |