  We propose an energy-efficient procedure for transponder configuration in
FMF-based elastic optical networks in which quality of service and physical
constraints are guaranteed and joint optimization of transmit optical power,
temporal, spatial and spectral variables are addressed. We use geometric
convexification techniques to provide convex representations for quality of
service, transponder power consumption and transponder configuration problem.
Simulation results show that our convex formulation is considerably faster than
its mixed-integer nonlinear counterpart and its ability to optimize transmit
optical power reduces total transponder power consumption up to 32%. We also
analyze the effect of mode coupling and number of available modes on power
consumption of different network elements.
