Cost and Energy Efficiency in Next-Generation Variable-Line-Rate Optical Networks By Avishek Nag B.S. (Jadavpur University, Kolkata, India) 2005 M.S. (Indian Institute of Technology, Kharagpur, India) 2007 Dissertation Submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering in the Office of Graduate Studies of the University of California Davis Approved: Biswanath Mukherjee, Chair Chen-Nee Chuah Jonathan P. Heritage Committee in Charge 2012 -i-