All-optical header processing based on nonlinear gain and index dynamics in semiconductor optical amplifiers

This thesis is devoted to all optical header recognition. All-optical header recognizers play an important role in futuristic all-optical packet switches. In the literature several approaches for all-optical header recognition have been discussed, but in this thesis, we focus on all-optical header recognition based on nonlinear gain and index dynamics in semiconductor optical amplifiers. After a general introduction on the topic, in Chapter 2 an all-optical packet switch concept is discussed. This packet switch contains an optical header processor that is operated by employing two-pulse correlation principles in a semiconductor optical (laser) amplifier that is placed in an optical loop mirror (SLALOM). The header processor used in the packet switch presented in Chapter 2 can only recognize 1 specific header pattern. In Chapter 3 of this thesis, it is shown how header recognition concepts that are based on two-pulse correlation principles can be extended to recognize a larger amount of packet headers. Also the packet switch presented in Chapter 2 contains an optical threshold function. This function was necessary since the header recognizer in the packet switch could only suppress the packet payload. Therefore in Chapter 4 and all-optical header preprocessor is discussed that solves this issue. In Chapter 5 of this thesis all-optical header processing is discussed employing selfinduced nonlinear polarisation rotation in a semiconductor optical amplifier. The advantage of employing header processing and header pre-processing employing nonlinear polarisation rotation is that the optical powers to be injected in the header processing system could be drastically reduced. Finally, In Chapter 6, we show concepts for all-optical header recognition employing terahertz optical asymmetric demultiplexers (TOADs). The advantage of employing TOADs instead of SLALOMs is that header recognizers employing TOADs can be made so compact so that the system allows photonic integration. In Chapter 6, a concept is presented in which TOADs are employed for optical header recognition. In contrast to other optical header recognition concepts employing TOADs, the one presented in Chapter 6 of this thesis does not require optical clock recovery