All-optical Tunable Delay Line Based On Wavelength Conversion And Dispersion And Its Applications

All-optical buffer is one of the key devices in the all-optical switching node. As a kind of method to achieve all-optical buffering, all-optical delay line has attracted great attention, due to its simple structure and convinient operation. In this paper, we propose and experimentally demonstrate a novel all-optical delay line based on wavelength conversion and fiber dispersion. This scheme is used to structure tunable and switchable ultrawideband (UWB) signal generation successfully. The main contents of the dissertation are as follows:(1) The basic theory and operation principle of the all-optical delay line based on wavelength conversion and dispersion are introduced. The cross-gain modulation (XGM) effect in semiconductor optical amplifier (SOA) to achieve wavelength conversion and the delay introduced by fiber dispersion are analyzed. An all-optical Manchester logic NOT gate is realized by using the XGM effect in SOA.(2) A novel all-optical delay line based on wavelength conversion in SOA and dispersion in dispersion-compensating fiber (DCF) is proposed. Using 10 Gbit/s signal, we obtain large range of continuous tunable time delay at long wavelength in C band in experiment. The simulation results show that this structure can also be used to generate time delay for 40 Gbit/s signal with good signal quality performance.(3) We propose a scheme based on reflective SOA (RSOA) wavelength conversion and single mode fiber (SMF). In experiment, we achieve very large delay at short wavelength in C band. The simulation shows that the scheme can get good signal quality performance when used to high speed situation.(4) We combine and simplify the two structures, and demonstrate a wideband tunable all-optical delay line. We obtained large time delay in the whole C band. The simulation of high-speed application shows that the signal quality is acceptable.(5) A tunable and switchable all-optical UWB signal generator is proposed and simulated, by using an SOA and an ODL. Through mechanical tuning of ODL, the pulsewidth and radio-frequency (RF) spectrum can be tuned and the pulse polarity can be switched. The output spectrum satisfied the definition of UWB well. (6) Using the all-optical tunable time delay mechanism, a filter-free all-optical tunable and switchable UWB monocyle generator is experimentally demonstrated. The pulsewidth and radio-frequency (RF) spectrum can be tuned and the pulse polarity can be switched, by varying the wavelength of the probe.