The rising demand for transmission capacity in optical networks has motivated
steady interest in expansion beyond the standard C-band (1530-1565 nm) into the
adjacent L-band (1565-1625 nm), for an approximate doubling of capacity in a
single stroke. However, in the context of quantum networking, the ability to
leverage the L-band will require advanced tools for characterization and
management of entanglement resources which have so far been lagging. In this
work, we demonstrate an ultrabroadband two-photon source integrating both C-
and L-band wavelength-selective switches for complete control of spectral
routing and allocation across 7.5 THz in a single setup. Polarization state
tomography of all 150 pairs of 25 GHz-wide channels reveals an average fidelity
of 0.98 and total distillable entanglement greater than 181 kebits/s. This
source is explicitly designed for flex-grid optical networks and can facilitate
optimal utilization of entanglement resources across the full C+L-band.Comment: 5 pages, 4 figure