Intersecting N x M star couplers for routing optical signals

摘要

Overlapped coupler combination Photonic Lightguide Circuits for routing optical signals within an optical communication system include at least two couplers whose planar slab waveguides are disposed in supportedly overlying relation so as to conserve wafer real estate. In a preferred form of the invention wherein a Dragone router is implemented, output waveguides of a first of the couplers are connected to the input waveguides of a second of the couplers at a predetermined angle so as to create path length differences in the individual optical signals traversing through the various waveguides. These path length differences ensure that the optical signals have good wavelength differentiation so that a large number of channels can be accommodated. The signals traverse through the couplers in uniform or non-uniform spaced channels of less than about 100 GHz, and more preferably less than about 25 GHz. The coupler combination devices are particularly useful as Dragone routers and other types of DWDM routers.