US Patent 7266299 Add/drop-drop and continue-module and drop and continue module

A tunable add/drop&continue or drop&continue module comprises two optical filters where at least one is tunable and that are arranged following one another between a branching unit for optical signals and an insertion unit follow a branching unit for optical signals. The reflection attenuation of the one tunable optical filter is lower and the transmission attenuation higher than that of the other optical filter, as a result of which the drop&continue function of the module can be realized without high circuit-oriented expense.