Research And Realization On Key Technologies In Ultra-high-speed Optical Communication Networks

With the rapid developments of the internet technology and information technology, the broadband networks become widespread in the world. A variety of new emerging network applications occupy a large number of network bandwidth, making Internet traffic doubling almost every two years. Due to the limits of "electronic bottleneck" of the used electronic device in existing optical communications networks, the highest commercial single-wavelength transmission rate is limited up to 40GBit / s. In order to improve the transmission capacity of transmission and information processing capability of core network nodes, new types of ultra-high-speed optical communication network should be studied extensively. This dissertation focuses on investigations of key technologies and issues in ultrahigh-speed photonics networks, included ultra-short-pulse generation technology, all optical wavelength conversion, ultra-fast multiplexing/demultiplexing systems and all optical switching network structures. The research work and results are summarized as follows:1. A linear cavity actively mode-locked fiber laser is demonstrated with a semiconductor optical amplifier (SOA) employing in the cavity. Without wavelength selective device in the cavity, the demonstrated mode-locked laser shows a very simple cavity configuration. A pulse train with pulsewidth about 6.8ps in a wide wavelength tunable span (1528 nm to 1565 nm) and a wide repetition tunable span (3 GHz to 10 GHz) is achieved successfully. The generated pulses show a low timing jitter about 60 fs.2. By injecting an external pulse forwardly into a ring cavity, an actively mode-locked fiber ring laser is demonstrated. Without any extral pulse compression, a pulse train with pulsewidth about 6ps is achieved with low timing jitter about 70fs. The mode-locked fiber laser presents a wide wavelength tunable span (1530nm-1565nm) and a wide repetition tunable span (1 GHz-15 GHz). A detailed experimentally research is done to investigate the relationship between the pulsewidth of generated pulse trains with the parameters of cavity and external pulse sequence. 3. 80 Gbit/s error-free polarity-preserved wavelength conversion was achieved by implementing cross gain modulation (XGM)/cross phase modulation (XPM) in an SOA in conjunction with shifted filtering. In contrast to other wavelength conversion schemes, the technique presented is advantageous in that the polarity of the output signal is preserved, the scheme exhibits polarization independence, and the set-up has a very simple configuration. In order to improve the performance of wavelength conversion, we analyze the impact of the shift between the wavelength of probe light and the central wavelength of OBPF.4. Base on the four-wave mixing effect in SOA, all-optical demultiplexing from 80Gbit/s to 10Gbit/s is achieved with a single SOA. The demultiplexing system can operate without bit error. For a 10^-9 bit error rate, the maximum power penalty is 3.5dB. In addition, an experimental analysis is done for the impact of input power of signal light on the bit error performance of the demultiplexing system.5. A new de-multiplexing scheme is proposed with a high-speed remain-block D flip-flop. This scheme shows a lot of advantages, such as signal regeneration, RZ-NRZ conversion, and stable operation. With this new scheme, a 10Gbit/s signal is de-multiplexed from a 40Gbit/s signal successfully.6. By combining the transparency of optical circuit switching networks and the large transmission capacity of optical time division multiplexing (OTDM) networks, an 80Gbit/s wavelength-routed all-optical switching networks is demonstrated based on high performance all-optical wavelength converter.