Network architectures and requirements for widely tunable lasers

The use of tunable lasers in a long haul network has two applications: sparing and optical networking. The justification for sparing is that the use of tunable lasers reduces the number of extra transponders (one for every wavelength) that service providers must stock. Several applications are covered in the term "optical networking". In general, wavelengths are changed remotely at any site in the network. This is important at nodes that are interconnections between rings called hub nodes.