In situations where fiber is not readily available, due to fiber exhaust or limited penetration, tunable lasers and DWDM are helping to expand capacity for metro, DCI and access applications. Even in areas where plenty of fiber is available, those techniques help maximize the ROI of a service provider’s fiber infrastructure. Further, advances in coherent technology and pluggable transceivers have enabled widespread deployment of IP over DWDM services and self-tuning algorithms have simplified the installation and maintenance of DWDM. As a result, metro transport, DCI and future access networks are moving towards coherent tunable pluggables, with annual sales forecast to double by 2026.