The next leap in optical transport will take us to 400G, says Dr. Jens Rasmussen, Director, Photonic Systems Labs at Fujitsu Laboratories. This will bring several keep benefits in operational savings and capital savings. 400G cards will be software-definable to enable a flexible mix of bit rates and thereby simplify inventory management. The leap to 400G is also about transporting more data on a single fiber. Fujitsu R&D is actively working on ways of improving spectral efficiency by bringing channels closer together. Adaptive modulation for line side cards includes support for today's QPSK and more complex formats like 8QAM and 16QAM.