  Thesis Statement: Cost-effective switching and spectrum utilization
efficiency have become critical design considerations in optical networks. This
dissertation provides in-depth exploration of these important aspects, and
proposes effective techniques for low-cost switching architectures and resource
allocation algorithms to facilitate the adoption of optical networks in the
near future.
  The dramatic growth of Internet traffic brings challenges for optical network
designers. The increasing traffic and bandwidth requirements mean that various
resource allocation schemes to achieve different network design goals assume
great importance. The general problem of resource allocation to lightpath
requests is a challenging problem.
  An emerging technology of flexible and more fine-grained grid through the use
of Optical Orthogonal Frequency Division Multiplexing (OOFDM) allows fiber
bandwidth to be more suitably matched up with application requirements, thereby
making the network more elastic than the conventional Wavelength Division
Multiplexing (WDM) optical networks. Despite the advances of employing OOFDM
technology in elastic optical networks (EONs), imminent fiber capacity
exhaustion due to the ever-increasing demands means that multiple fibers per
link will be inevitable. While increasing the number of fibers boosts the
capacity of networks, there is a price to pay for it in the form of increased
number of switch ports / complexity of switches. The huge amount of traffic
demands and thus high hardware requirements motivate multigranularity (such as
wavebanding) to save costs in optical networks. This dissertation aims to
tackle several types of resource allocation challenges in multi-granular
optical networks to either improve the spectrum utilization or provide
cost-effective switching techniques.
