Variable delay device for an optical component such as a polarization mode dispersion compensator

A variable delay component utilized to correct polarization mode dispersion in an optical signal having a fast polarization mode component, a slow polarization mode component, and an initial polarization mode differential therebetween, the variable delay component comprising:

• a plurality of optical fiber delay elements each having a fast axis and a slow axis capable of transmitting a selected polarization mode;
• and
• a plurality of polarization selectors optically coupled to the plurality of optical fiber delay elements, the plurality of delay optical fiber elements and the plurality of polarization selectors disposed in series with one another such that the optical signal traverses each of the plurality of polarization selectors and each of the plurality of optical fiber delay elements as the optical signal traverses the variable delay component, the fast polarization mode component of the optical signal being generally aligned with the slow axis of at least one of the plurality of optical fiber delay elements to impose an incremental delay on the fast polarization mode component of the optical signal, at least one of the plurality of polarization selectors being selectively actuated to translate the fast polarization mode component of the optical signal to the fast axis of subsequent ones of the plurality of optical fiber delay elements so as not to impose an incremental delay on the fast polarization mode component of the optical signal, such that the sum of the incremental delays imposed by the plurality of optical fiber delay elements on the fast polarization mode component of the optical signal generally corrects for the initial polarization mode differential.

A delay component utilized to correct polarization mode dispersion in an optical signal having a fast polarization mode component, a slow polarization mode component, and an initial polarization mode differential therebetween, the variable delay component comprising:

• an optical fiber delay element having a fast axis and a slow axis each capable of transmitting a selected polarization mode;
• and
• a polarization rotator optically coupled to the optical fiber delay element, the delay element and the polarization rotator disposed in series with one another such that the optical signal traverses the polarization rotator and the optical fiber delay element, the polarization rotator selectively actuated to rotate the fast polarization mode component of the optical signal to the slow axis of the optical fiber delay element so as to impose an incremental delay on the fast polarization mode component of the optical signal, or the polarization rotator selectively actuated to not rotate the fast polarization mode component of the optical signal to the slow axis of the optical fiber delay element so as not to impose an incremental delay on the fast polarization mode component of the optical signal, such that the incremental delay imposed by the optical fiber delay element on the fast polarization mode component of the optical signal generally corrects for at least a portion of the initial polarization mode differential.

A method for compensating for polarization mode dispersion in a optical signal having a fast polarization mode component, a slow polarization mode component, and an initial polarization mode differential therebetween, the method comprising the steps of:

• providing a plurality of optical fiber delay elements each having a fast axis and a slow axis capable of transmitting a selected polarization mode, each of the plurality of optical fiber delay elements having an incremental delay associated with the slow axis thereof;
• providing a plurality of polarization selectors, the plurality of optical fiber delay elements and the plurality of polarization selectors being disposed in series and alternating with one another such that the optical signal traverses each of the plurality of polarization selectors and each of the plurality of optical fiber delay elements as the optical signal traverses the variable delay component;
• and
• selectively actuating one or more of the polarization selectors in a predetermined pattern to translate the fast polarization mode component of the optical signal to the slow axis of one or more of the plurality of optical fiber delay elements so as to impose one or more of the incremental delays on the fast polarization mode component of the optical signal, such that the sum of the one or more incremental delays imposed by the plurality of optical fiber delay elements on the fast polarization mode component of the optical signal generally corrects for the initial polarization mode differential.

In a polarization mode dispersion compensator utilized to correct polarization mode dispersion in an optical signal having a fast polarization mode component, a slow polarization mode component, and an initial polarization mode differential therebetween, the polarization mode compensator including a device for discriminating between the fast polarization mode component and the slow polarization mode and for measuring the initial polarization mode differential, a variable delay device for imposing a selected delay on the fast polarization mode component of the optical signal, and a control device for adjusting the variable delay device in response to the initial polarization mode differential measured, the improvement in the variable delay device comprising:

• a plurality of optical fiber delay elements each having a fast axis and a slow axis and an incremental delay associated with the slow axis thereof;
• and
• a plurality of polarization rotators optically coupled to and disposed in series alternating with the plurality of optical fiber delay elements, such that one or more of the polarization rotators may be actuated in a predetermined pattern to selectively rotate the fast polarization mode component of the optical signal to the slow axis of one or more of the plurality of optical fiber delay elements so as to impose one or more of the incremental delays on the fast polarization mode component of the optical signal, such that the sum of the one or more incremental delays imposed by the plurality of optical fiber delay elements on the fast polarization mode component of the optical signal generally corrects for the initial polarization mode differential.

A variable delay component utilized to correct polarization mode dispersion in an optical signal having a first mode component, a second mode component, and an initial differential therebetween, the variable delay component comprising:

• a plurality of optical fiber delay elements each having a fast optical characteristic and a slow optical characteristic capable of transmitting a selected optical mode;
• and
• a plurality of selectors optically coupled to the plurality of optical fiber delay elements, the plurality of optical fiber delay elements and the plurality of selectors disposed in series and alternating with one another such that the optical signal traverses each of the plurality of selectors and each of the plurality of optical fiber delay elements as the optical signal traverses the variable delay component,
• a first of the plurality of selectors being selectively actuated to translate the first mode component of the optical signal to be associated with the slow optical characteristic at least one of the plurality of optical fibers delay elements so as to impose an incremental delay on the first mode component of the optical signal, such that the sum of the incremental delays imposed by the plurality of optical fiber delay elements on the first mode component of the optical signal generally corrects for the initial differential.