Channelmania! – future proof your DWDM network topology while keeping it flexible for 1.6T#

Thomas Weible - Flexoptix

• Why: DWDM topology planning for the 800G/1.6T coherent era — squarely in the PM's physical WAN interconnect interest. This is about how to structure a C-band plant so future superchannels don't strand you.
• What: An argument for planning DWDM networks in frequency terms (THz/GHz) rather than channel numbers or wavelengths, and for a "colorless," flexible architecture: carve the C-band into 12 × 400 GHz subbands using low-cost PLC 1×4 splitters to combine TX / split RX, and run each subband through ordinary 50 GHz DWDM MUX/DeMUX. This yields DIY coherent superchannels (425 Gbps @ 53.125 GBd dual-polarization 16-QAM per the deck) that can be re-arranged as optics evolve. The deck also notes ~100 GHz spacing as the observed optimum (attributed to Blake Willis), 800G ZR+ in DD/OSFP form factors arriving, 12.8T liquid-cooled XPO optics approaching, 300 GHz options appearing, and that coherent BIDI needs a second laser for the RX local oscillator.
• How: Coherent intradyne detection with phase- and polarization-diversity balanced receivers; higher-order modulation constellations (4 bits/symbol × 2 polarizations); superchannels assembled from COTS PLC splitters plus standard DWDM muxes; "make a frequency plan for your spans."
• Where applicable: Operators building or re-planning their own DWDM plant. This is a vendor session (Flexoptix sells tunable optics), but the frequency-plan method and superchannel construction approach are vendor-neutral engineering. The slide text is fragmentary and fast-paced; expect the talk to be denser than the deck.