This paper describes recent progress in relation to the key optical devices for high-speed digital coherent transmission, namely coherent receivers and advanced-format modulators. Miniaturization and higher performance have been achieved on a silica-based planar lightwave circuit (PLC) platform and it has been integrated with other key materials.
Shin Kamei, Shin Kamei,
"Compact optical devices for high-speed digital coherent link", Proc. SPIE 9008, Optical Metro Networks and Short-Haul Systems VI, 900805 (1 February 2014); doi: 10.1117/12.2042117; https://doi.org/10.1117/12.2042117