Document Type

Theses, Ph.D

Rights

This item is available under a Creative Commons License for non-commercial use only

Publication Details

Successfully submitted for the Award of Doctor of Philosophy to the Dublin Institute of Technology, August, 2010.

Abstract

In today's information age demand for ultra-fast information transfer with ultra-high bandwidths has reached extraordinary levels. Hence, the transmission in the future internet-backbone will be increasingly constrained in the network nodes. At the same time, the power consumption of the network systems will increase to unsustainable levels. To overcome these constraints power-ecient photonic networks which provide ultra-fast all-optical switching and routing are essential. Nowadays, optical signal processing and switching can be implemented relatively easily. However, the realization of optical bu ers and short-term memories is still an unsolved challenge. The slow- and fast-light e ect has been investigated as one solution for the optical bu ering over the last few years. It means the slowing down and acceleration of the group velocity of light pulses in a medium. To realize this, many di erent methods and material systems have been developed but due to its signi cant advantages the nonlinear e ect of stimulated Brillouin scattering (SBS) is particularly promising. However, it also su ers from disadvantages which limit the slow- and fast-light performance. In this thesis the slow- and fast-light e ect using SBS is investigated. SBS-based slow- and fast-light utilizes the generation of arti cial resonances by the coupling of a strong pump wave inside an optical ber. This creates gain and loss regions in which a counterpropagating signal wave can be ampli ed and attenuated, but slowed down and accelerated as well. The properties of such a system depend directly on the Brillouin spectrum. Thus, the focus of this work is the analysis of opportunities to overcome the natural limits of SBS-based slow-light by the optimization of the transfer function. Therefore, di fferent novel methods for a bandwidth enhancement, an enhancement of the maximum achievable time delay and a reduction of the output pulse distortions are investigated in theory and experiment. This includes the theoretical background and practical limits of these methods. The most important results are a bandwidth enhancement to a multiple of the natural Brillouin bandwidth up to the GHz range, a time delay enhancement of up to four times of the initial pulse width and a signi cant distortion reduction of the output pulses by 25 %. Although there are various potential applications for the slow- and fast-light e ect, this work examines the topic mainly under the aspect of information and communication systems. Thus, this thesis will show that SBS-based slow- and fast-light is a reliable and ecient candidate to realize all-optical short-term bu ers. Despite the small storage capacity compared to other techniques, it can be used for an accurate synchronization, multiplexing and equalization of multiple high bit rate data channels as well as for phasedarray antennas.