Investigations On Characteristics And Applications Of Injection Mode-locked Laser Based On SOA

All optical 3R regeneration is an effective method to overcome the optical signal degradation in the long haul transmission systems. All optical clock recovery is one of the key technologies in the 3R regeneration system. In this thesis, injection mode locked laser (IMLL) based on semiconductor optical amplifier (SOA) is applied for all optical clock recovery because of its advantages, such as simple configuration, wavelength tunability, stability, low cost and commercially available product, etc. SOA is the key component in IMLL, whose carrier density is modulated by the injected signal. Thus the light in the loop is modulated due to the cross gain modulation (XGM) and the cross phase modulation (XPM). At the same time, the light in the loop also modulates the gain of SOA. To our knowledge, there are no reports about the theory of simulation for IMLL based on SOA at present. In this thesis, a numerical simulation model of the IMLL based on SOA was established, by which the impacts of some parameters, such as the injected signals, noise of SOA, on the clock recovery was investigated. It is found in the numerical simulation and experiment, there is amplitude fluctuation and timing jitter in the clock pulses recovered from the IMLL, which is called as pattern effect,because of the long recovery time of the carriers in the SOA. This is the most serious flaw of the IMLL based on SOA for clock recovery. In this thesis, an approach called comb-like filter preprocessing was proposed. Numerical calculation demonstrates that this method is very effective to reduce the pattern effect in the clock recovery. As the comb-like filter with higher finesse requires higher precision of free spectrum range (FSR) and lower jitter of signal wavelength, a comb-like filter with low finesse (about 21) and an SOA were combined to preprocess the signal. With this technology, 10Gb/s and 40Gb/s clock recovery were successfully demonstrated. Clock recovery and 3R regeneration from degraded signals are researched in many laboratories. By preprocessing the data signals with the combination of comb-like filter and SOA, 10GHz clock pulses with low jitter and high extinction rate were successfully recovered from the serious degraded signals. 10Gb/s 3R regeneration was also demonstrated from the degraded signals, where an electro-absorption modulator (EAM) was used as an optical switch. All optical clock division and multiplication is an important technology in the future all optical networks. In this thesis, with the IMLL based on SOA, we not only realized the frequency division for 10GHz and 20GHz but also demonstrated the non-integer frequency multiplication. Amplitude equalization for optical pulses is one of the commonly used technologies in the experiment. It was demonstrated experimentally that IMLL based on SOA could be used for amplitude equalization without waveform distortion and wavelength tunable operation.