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Polarization control apparatus and associated method

  • US 6,526,187 B1
  • Filed: 05/17/2001
  • Issued: 02/25/2003
  • Est. Priority Date: 05/17/2001
  • Status: Expired due to Term
First Claim
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1. An optical polarization controller that controls a first temporal separation between a first polarization and a second polarization of an output optical signal, wherein a second temporal separation exists between a first polarization and a second polarization of an input optical signal, the optical polarization controller comprising:

  • a controller that determines the first temporal separation, the controller compares the first temporal separation with the second temporal separation;

    a polarization separation device that transmits the first polarization of the output optical signal along a first path and transmits the second polarization of the output optical signal along a second path; and

    a delay element that delays the first polarization of the output optical signal relative to the second polarization of the output optical signal whereby a duration of the first temporal separation becomes closer to a duration of the second temporal separation, the delay element further comprising;

    a waveguide that includes an input port wherein the input optical signal is introduced into the waveguide, an output port wherein an optical signal exits the waveguide, and a region of changeable propagation constant disposed along a length of the waveguide and between the input port and the output port, wherein the input optical signal is guided by total internal reflection in the waveguide, and the waveguide is formed at least in part from an active semiconductor, a first electrode positioned proximate a first surface of the region of changeable propagation constant and electrically separated from the active semiconductor, a second electrode in electrical contact with the active semiconductor and disposed on a first side of the region of changeable propagation constant, a two-dimensional electron (hole) gas (2DEG) having a free carrier distribution that is formed on the first surface of the active semiconductor when a voltage is applied between the first electrode and the second electrode, and wherein changing the voltage causes a corresponding change of the free carrier distribution which, in turn, causes corresponding change of a propagation constant level in the region of changeable propagation constant that changes a duration that the first polarization of the output optical signal is flowing through the region of changeable propagation constant.

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