Patent ID: 6647209
Filing Date: 2003-11-11
Classification: G02B,H04B,H04J

Abstract:
An apparatus for switching signals in an optical fiber between add, drop and pass-through status, the apparatus comprising:(1) a demultiplexer for demultiplexing the different wavelength signals carried on the optical fiber; (2) a first switching array for selecting which demultiplexed signals are routed to a drop port and which demultiplexed signals are to be pass-through signals; (3) a second switching array for receiving the pass-through signals and an optional added signal from an add port; and (4) a multiplexer for multiplexing the signals from the second switching array and multiplexing the signals into an output port, wherein each of the demultiplexer and multiplexer comprises: (a) an integrated optical fan-out circuit having a first side and a second side and a plurality of integrated waveguides, each extending between the first and second sides, wherein the waveguides have sufficient separation and are configured and adapted to be coupled to a linear array of optical fibers at the first side, and wherein the separation between the waveguides at the second side is smaller than that at the first side; (b) a beam splitter configured and adapted to receive the plurality of light beams and to split each of the beams into a p-polarized beam and s-polarized beam; (c) a polarization rotator configured and adapted to rotate the polarization direction of either the p-polarized beams or the s-polarized beams by substantially 90 degrees relative to the other polarized beams; (d) a diffraction grating configured and adapted to diffract each of the beams of different wavelength into a different angular direction; (e) a polarization rotator configured and adapted to rotate the polarization direction of the p-polarized beams or the s-polarized beams rotated by component (c) by substantially 90 degrees relative to the other polarized beams; and (f) a beam combiner configured and adapted to receive the plurality of light beams and to combine the p-polarized beams and s-polarized beams into a single beam having a plurality of wavelengths, whereby the device is capable of multiplexing a plurality of light beams of different wavelengths when it is disposed such that the beams propagate sequentially through components (a) through (f), and of demultiplexing a beam containing a plurality of wavelengths when the device is disposed such that the beam propagates sequentially through components (f) through (a).