Fiber Ultra-Short Pulse Generation And All-Optical Wavelength Conversion

The combination of optical time division multiplexing (OTDM) and wavelength division multiplexing (WDM) technologies will be the trend in near future optical network, which put the researches on components into focus. This dissertation is focused on ultra-short pulse sources and all optical wavelength conversion, which include:Nonlinear polarization rotation passively mode-locked fiber laser Influence of cavity parameters on output pulse width, chirp, bandwidth and stability is investigated numerically.Stable, self-starting 1.5ps mode-locked pulse at 13.9MHz repetition rate is obtained. Transform-limited pulse with wavelength continuously tunable over 9nm is obtained for the first time. The output pulse is compressed to 750fs with 50m single mode fiber (SMF) and beautiful division figure of high-order soliton is observed. Actively-passively mode-locked fiber laser with a DI-NOLMSwitching characteristics of dispersion-imbalanced nonlinear optical loop mirror (DI-NOLM) is investigated numerically in detail.11ps stable mode-locked pulse train and 20GHz, 30GHz harmonic mode-locked pulses with uniform amplitude are obtained with the figure-eight structure.Fiber supercontinuum (FSC) pulse source The influences of nonlinear effects of fiber, fiber parameters and pump pulse parameters on superconitnuum (SC) spectrum are studied numerically.SC is generated and sliced in fibers with different dispersion characteristic and length. More than 450nm 20dB bandwidth is generated with uniformity within (0.25dB over hundreds of nanometers for the first time.All wavelength conversion based on FWM in SOAInfluence of important parameters on conversion efficiency and signal-noise ratio (SNR) are studied numerically. It is also analyzed that constant efficiency and SNR can be obtained in a wide detuning range with orthogonally polarized pump mechanism. The output 10GHz pulse of electro-absorption modulated laser (EAL) is wavelength converted by using FWM in SOA. Meanwhile, only 3.88dB fluctuation of conversion efficiency over 52nm wavelength detuning range is obtained by using orthogonally polarized pump for the first time.Gain-flattening of erbium-doped fiber amplifier with fiber loop mirror (FLM)The method of EDFA gain flattening using a FLM acting as a wavelength filter is analyzed in theory. The feasibility of using closely twisted SMF generating birefringence to construct FLM is brought forward for the first time.Experimentally, an ASE flatness of (0.6dB within 34nm is obtained, which is the best result with similar method until now.