Novel Optical Techniques to Enable Network Management in All-Optical Networks

This thesis addresses three important network management aspects of optical networks, namely, optical lightpath tracing problem for all-optical networks, all-optical packet buffering in optical packet switching networks, power-efficient operation in wavelength division multiplexing passive optical networks (WDM-PON).;Lightpath tracing through all-optical encoder: In an all-optical reconfigurable wavelength routing network, the lightpath of the optical data packets can be reconfigured, via the optical cross connects (OXC) residing at each network node. In order to monitor any possible routing errors, any possible causes of signal quality degradation, detect any source of malicious or attack traffic and provide quality of service (QoS) aware next-hop routing strategy, monitoring of lightpath of optical data packets is necessary. This scheme encodes the lightpath information into the label of individual optical packet. Each network node is assigned with a distinct prime number as an identification tag. By using the optical encoders located at the outputs of OXCs, the label value of the packets will be multiplied by the prime number designated to the respective OXC, residing at the network node. Hence, the information of the network nodes that the packet has traversed will be encoded to the label as the product of all the prime numbers assigned to all traversed network nodes. Therefore, at the destination node, the whole physical lightpath of each received optical data packet can be easily identified through factorization of the encoded label value.;Our scheme provides substantial reduction in the requirement of fiber delay lines, as compared to the time-delay recognition techniques. It offers fast detection when comparing with pilot tone detection method. Besides, possible network looping problem can be detected and the encoded label can be acted as time-to-live (TTL) identifier of the optical packet.;All-optical power-controlled optical packet buffer: All-optical packet buffer is essential for the contention resolution in all-optical packet switching network. In order to realize simple and efficient operation of optical packet buffer, we propose the use of all-optical power-controlled packet buffer for which the number of circulating loops is controlled by the input signal power (i.e. input signal with higher power will experience longer delay). We formulate the problem of designing a re-circulating delay buffer into signal power dependent filtering problem. The optical OOK signal first passes through a re-circulating loop generating multiple copies at different time instants that each delayed copy will have halved power as the previous one. Then it will pass through the signal power dependent filter implemented by using optical nonlinear effect. The filter has the characteristics that only signal (packet copy) with specific power level can be outputted while the others get attenuated and therefore cleared. As a result, in order to change the amount of delay, we just need to change the input signal power such that the signal with specific delay will fall into the pass band of the power dependent filter and get outputted.;Compared with other delay schemes which use many SOAs as gates to control the number of re-circulating delay or implementing tunable wavelength converter and passes through wavelength dependent delay, our scheme provides easy control of the delay required.;Signaling techniques for power-efficient operation of WDM-PON: In WDM-PON, the upstream signal at the optical network unit (ONU) can be generated by re-modulating the downstream signal received from the optical line terminal (OLT). However, the conventional architecture may suffer from power consumption problem. When there is no downstream signal, the ONU is not able to send any upstream data. Thus even if there is no traffic on the line, the OLT has to send the downstream signal continuously, in order to ensure the ONU can always be able to send its upstream data. In such networks, burst-mode traffic transmission can provide improvement on power efficiency. We propose a signaling technique to send "Wake Up" message from the ONU to OLT, to notify the transceiver of the OLT to recover from sleep mode. It is done by modulating the Amplified Spontaneous Emission (ASE) noise in RSOA at the ONU with the particular ONU specific pilot tone monitoring signal. Thus, it does not require the presence of the remodulating downstream signal. At the OLT, a specific module is needed for the detection of the pilot tones from different ONUs and then activate the corresponding transceiver. Our scheme offers simple and cost-effective approach for power-efficient operation in the WDM-PON.