Channelmania! Secure the Future of your DWDM Network Topology Remaining Flexible to 1.6T Technology#

Gerhard Stein (Flexoptix; slides also credit Thomas Weible and Gert Matyasowicz, Flexoptix)

• Why: Physical optics and WAN transport are core to this PM, and this is the program's one deep-dive into coherent optics physics and DWDM topology planning for the 800G/1.6T era. Caveat: it is vendor-presented (Flexoptix), but the slides are engineering-heavy — constellation math, receiver architectures, spectrum planning — not a product pitch.
• What: A technical walkthrough of why coherent transceivers only recently became feasible, and how to design DWDM topologies that stay flexible as line rates scale. Covers on-off-keying's limits, higher-order modulation (16-constellation/4-bit patterns over two orthogonal polarizations, 425 Gbps at 53.125 GBd), and coherent receiver design (balanced/asymmetric detection, phase and polarization diversity, homo-/hetero-/intradyn detection).
• How: The core prescription is to stop planning in wavelengths (nm, channel numbers) and plan in spectrum (THz/GHz): contrast 96 × 50 GHz C-band channels (~2 dB insertion loss) with 12 × 400 GHz sub-bands; the authors show a DIY superchannel using cheap PLC splitters and ordinary 50 GHz DWDM mux/demux with coherent RX, and note 800G coherent ZR+ OSFP pluggables shipping today with XPO (up to 12.6T, liquid-cooled) arriving.
• Where applicable: Any operator or DC interconnect planning C-band capacity upgrades and topology flexibility toward 1.6T. The spectrum-planning argument is broadly applicable; the framing leans toward Flexoptix's programmable-transceiver business, so vendor-fit should be discounted.