Optical monitoring of the angular position of micro mirrors in an optical switch
First Claim
Patent Images
1. An optical switch for selectively switching optical signals between input fibers and output fibers, comprising:
- a switching substrate including a plurality of micro-mirrors that are individually tiltable about at least a first axis relative to the switching substrate, the micro-mirrors for reflecting optical signal beams and an out-of-band optical position control signal beam incident thereto, the optical signal beams and out-of-band position control signal beam being reflected in selected angular directions based on tilt angles of the micro-mirrors about at least the first axis;
a beam splitter positioned in an optical path of the optical signal beams and the out-of-band optical position control signal beam reflected from the micro-mirrors, wherein the optical signal beams and the out-of-band position control signal beam exit the beam splitter in different directions;
an optical position detector having a sensing surface;
a lens assembly for focusing the out-of band optical position control signal beam from the beam splitter to produce at least one beam spot on the sensing surface of the optical position detector, wherein the optical position detector generates beam spot position signals indicative of the position of the at least one beam spot on the sensing surface; and
control circuitry that generates control signals for controlling tilt angles of the micro-mirrors of the switching substrate responsive to the beam spot position signals.
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Abstract
The position of a micro-mirror, for example, in an optical switch, may be monitored using an optical position control signals that are detected by a detector arrangement. The position of the micro-mirror may be adjusted by detecting the position of the beam spot and comparing the detected position to a desired position.
67 Citations
22 Claims
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1. An optical switch for selectively switching optical signals between input fibers and output fibers, comprising:
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a switching substrate including a plurality of micro-mirrors that are individually tiltable about at least a first axis relative to the switching substrate, the micro-mirrors for reflecting optical signal beams and an out-of-band optical position control signal beam incident thereto, the optical signal beams and out-of-band position control signal beam being reflected in selected angular directions based on tilt angles of the micro-mirrors about at least the first axis;
a beam splitter positioned in an optical path of the optical signal beams and the out-of-band optical position control signal beam reflected from the micro-mirrors, wherein the optical signal beams and the out-of-band position control signal beam exit the beam splitter in different directions;
an optical position detector having a sensing surface;
a lens assembly for focusing the out-of band optical position control signal beam from the beam splitter to produce at least one beam spot on the sensing surface of the optical position detector, wherein the optical position detector generates beam spot position signals indicative of the position of the at least one beam spot on the sensing surface; and
control circuitry that generates control signals for controlling tilt angles of the micro-mirrors of the switching substrate responsive to the beam spot position signals. - View Dependent Claims (2, 3, 4)
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5. An optical switch for selectively switching optical signals between input fibers and output fibers, comprising:
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a switching substrate including a plurality of micro-mirrors that are individually tiltable about first and second axes relative to the switching substrate, the micro-mirrors for reflecting optical signal beams and an out-of-band optical position control signal beam incident thereto, the optical signal beams and out-of-band position control signal beam being reflected in selected angular directions based on tilt angles of the micro-mirrors about the first and second axes;
a beam splitter positioned in an optical path of the optical signal beams and the out-of-band optical position control signal beam reflected from the micro-mirrors, wherein the optical signal beams and the out-of-band position control signal beam exit the beam splitter in different directions;
an optical position detector having a sensing surface;
a lens assembly for focusing the out-of band optical position control signal beam from the beam splitter to produce at least one beam spot on the sensing surface of the optical position detector, wherein the optical position detector generates beam spot position signals indicative of the position of the at least one beam spot on the sensing surface; and
control circuitry that generates control signals for controlling tilt angles of the micro-mirrors about the first and second axes responsive to the beam spot position signals. - View Dependent Claims (6, 7, 8, 9, 10)
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11. An optical switch, comprising:
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a plurality of input optical fibers for propagating optical signals and a first out-of-band optical position control signal in a forward direction;
a first plurality of lenses for converting the optical signals into optical signal beams and for converting the first out-of-band optical position control signal to a first out-of-band optical position control signal beam;
a plurality of output optical fibers that propagate a second out-of-band optical position control signal in a reverse direction;
a second plurality of lenses for converting the second out-of-band optical position control signals to a second out-of-band optical position control beam;
first and second switching substrates, each of the first and second switching substrates including a plurality of micro-mirrors that are individually tiltable about first and second axes, wherein;
(i) the micro-mirrors of the first switching substrate reflect the optical signal beams from the first plurality of lenses to selected micro-mirrors of the second switching substrate and reflect the first out-of-band optical position control beam and (ii) the micro-mirrors of the second switching substrate reflect the optical signal beams from the micro-mirrors of the first switching substrate through the second plurality of lenses and into the output fibers for propagation in the forward direction, whereby the optical signals from the input optical fibers are selectively switched to the output optical fibers, said micro-mirrors of the second switching substrate further reflecting the second out-of-band optical position control signal;
one or more beam splitters positioned in an optical path between the first and second switching substrates, wherein the one or more beam splitters allow the optical signal beams to pass between the first and second switching substrates, direct the first out-of-band optical position control signal beam in a first direction, and direct the second out-of-band optical position control signal beam in a second direction;
first and second optical position detectors, each having a sensing surface;
a first lens assembly for focusing the first out-of band optical position control signal beam from the beam splitter to produce at least one beam spot on the sensing surface of the first optical position detector, wherein the first optical position detector generates first beam spot position signals indicative of the position of the at least one beam spot on the sensing surface of the first optical position detector;
a second lens assembly for focusing the second out-of band optical position control signal beam from the beam splitter to produce at least one beam spot on the sensing surface of the second optical position detector, wherein the second optical position detector generates second beam spot position signals indicative of the position of the at least one beam spot on the sensing surface of the second optical position detector; and
control circuitry that generates control signals for controlling tilt angles of the micro-mirrors of the first and second switching substrates about the first and second axes responsive to the first and second beam spot position signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method for optically monitoring the position of micro-mirrors in an optical switch, comprising:
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directing optical beams to a switching substrate, wherein the switching substrate comprises a plurality of micro-mirrors that reflect the optical beams in accordance with selected tilt angles of the micro-mirrors, the tilt angles of the micro-mirrors being individually controllable, and wherein the optical beams comprise optical signal beams and at least one of the optical beams comprises an optical signal beam and an out-of-band optical position control beam;
splitting the optical beams reflected from the micro-mirrors so that the optical signal beams and the out-of band optical position control beam are directed in different directions;
inserting the optical signal beams in selected output optical fibers; and
focusing the out-of-band optical position control beam on a sensing surface of a optical position detector, wherein a beam spot formed on the sensing surface by the focused out-of-band optical position control beam varies spatially in accordance with the tilt angle of the micro-mirror that reflected the out-of-band optical position control signal;
sensing the spatial location of the beam spot on the sensing surface;
generating beam spot position signals; and
controlling the tilt angle of the angle of the micro-mirror that reflected the out-of-band optical position control signal in accordance with the beam spot position signals. - View Dependent Claims (20, 21, 22)
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Specification