Patent ID: 6459826
Filing Date: 2002-10-01
Classification: H04Q

Abstract:
An optical switch apparatus arranged as an Add/Drop unit comprisinga programmable optical polarization unit for receiving an input optical signal and for selecting the polarization of an output signal in response to a control signal; a first polarization beam splitter (PBS) for splitting the selected polarization output signal from the programmable optical polarization unit into a first and second orthogonally polarized signals; a feedback circuit for coupling a feedback signal indicative of the optical signal strength of at least one of the orthogonally polarized signals back to the programmable optical polarization unit; wherein the programmable optical polarization unit adjusts the polarization of the selected polarization output signal in response to the feedback signal; wherein the first PBS operates as a drop unit where the first orthogonally polarized signal, produced in response to a first control signal, is outputted at a first port and the second orthogonally polarized signal, produced in response to a second control signal, is outputted at a drop port; and a second PBS having only one connection to the first PBS, that connection being from a first port of the first PBS to the first port of the second PBS so that the first orthogonally polarized signal passes to an output port of the second PBS and wherein a new second orthogonally polarized signal received at an add port of the second PBS is combined with the first orthogonally polarized signal to produce a combined output signal at the output port.