Theoretical And Experimental Study On Mode-locked Fiber Laser

A stable optical ultra short pulse source with a high repetition rate is very important for realizing future ultra-high speed optical communication. The actively mode locked fiber laser is very attractive among many potential optical sources in future all optical communication systems. In this dissertation, we theoretically and experimentally study in the field of actively mode locked fiber laser and in its relative fields. The main contents are as follows:1. In the experiment, by detuning the modulation frequency a fraction of the cavity fundamental frequency (fc) qfc/p from the harmonic frequency, where q and p are relative prime integers and q is less than p, we demonstrated a high order rational harmonic mode locked fiber ring laser. The highest order obtained in the experiment is up to 25. The properties of the rational harmonic mode locked pulse train are also discussed.2. We propose two types of dual-wavelength mode locked fiber ring lasers, which are using parallel or series connections of fiber Bragg gratings (FBGs) as wavelength selectors. The lasers can generate dual-wavelengths mode locked pulses with different repetition rates in only one ring cavity.3. We theoretically analyze the pulse train generated by a rational harmonic mode locked fiber ring laser by using the time domain analysis method. Based on the analysis, we propose a simple method to equalize the pulse amplitude in a rational harmonic mode locked fiber ring laser when the rational harmonic order is less than 5 by using the modulator as both a mode locker and a pulse amplitude equalizer in the ring cavity.4. In an actively mode locked fiber ring laser which use an F-P laser diode (F-P LD) as the modulator, we use a high birefringence fiber loop mirror as a periodic multichannel wavelength filter to select a laser mode emitted by the F-P LD. With this method, the output laser can be selected rapidly in 12 continuous modes in a range of 9.88nm.5. With the method of utilizing temporal spectral multiplexing of pulses in the gain medium to reduce gain cross saturation effects, a novel dual-wavelength actively mode locked fiber ring laser with an F-P LD as the modulator is proposed. The...