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US 7,067,795 B1Granted
Methods and systems for dynamic control of polarization of an optical signal
AssigneeGeneral Photonics Corporation
InventorsLianshan Yan, X. Steve Yao, Yongqiang Shi
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Abstract
Techniques and systems for dynamically controlling polarization of an optical signal by using various feedback controls, and by combining both feed-forward and feedback controls. Various dynamic control algorithms for such systems and other optical systems have been disclosed.
Claims20
A method for controlling polarization of light with a polarization controller which comprises a plurality of adjustable polarization elements, comprising:
- directing an input beam of light through the adjustable polarization elements of the polarization controller;
- measuring at least a portion of light transmitted through the polarization controller to produce a feedback signal;
- in response to the feedback signal, controlling the adjustable polarization elements of the polarization controller, one element at a time, to maximize or minimize the feedback signal, in order to control the polarization of the light transmitted through the polarization controller;
- and
- when an adjustable polarization element that is being adjusted operates near a limit of an operating range, adjusting the control of the adjustable polarization element to be away from the limit while adjusting other adjustable polarization elements, one at a time, to maximize or minimize the feedback signal until the adjustable polarization element is operated within a range that is away from an upper limit and an lower limit of the operating range without resetting any of the adjustable polarization elements in the polarization controller.
2 more elements
A device, comprising:
- a polarization controller which comprises a plurality of adjustable polarization elements along an optical path in series and operates to control polarization of light that transmits through the optical path, wherein each adjustable polarization element is adjustable in response to a control voltage to change the polarization of the light;
- a sensing unit to measure at least a portion of the light transmitted through the polarization controller and to produce a feedback signal from the measurement;
- and
- a feedback control which processes the feedback signal and responds to the feedback signal to control the adjustable polarization elements, one element at a time, to maximize or minimize the feedback signal without resetting any of the adjustable polarization elements in the polarization controller,
- wherein the feedback control is adapted to determine whether an adjustable polarization element that is being adjusted operates near a limit of an operating voltage range, and to adjust the control voltage of the adjustable polarization element to be away from the limit while adjusting other adjustable polarization elements, one at a time, to maximize or minimize the feedback signal until the adjustable polarization element is operated within a range that is away from an upper limit and an lower limit of the operating voltage range without resetting any of the adjustable polarization elements in the polarization controller.
2 more elements
Dependencies are inferred from the claim text.