Over the last 10 years, advances in optical transport based on digital coherent detection have enabled significant improvements in the cost per bit by transmitting higher and higher capacities. To achieve higher capacities, vendors have increased the bandwidth of components, utilized higher-order modulations, and improved algorithms, such as Forward Error Correction (FEC). At the same time, advances in CMOS process nodes and integrated photonics have enabled smaller pluggable form factors and lower power dissipation.
As coherent interfaces have evolved from bulky discrete solutions toward pluggables, there has generally been a