Fast attenuator
First Claim
1. An optical attenuator comprising:
- an input port and an output port;
a deformable membrane having a reflective surface disposed to reflect light launched from the input port substantially towards the output port, the membrane supported by a frame having a radially symmetric opening; and
deforming means for controllably deflecting the membrane into the opening such that the reflective surface forms a concave mirror having a concavity that determines the optical coupling efficiency between the input and output ports.
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Accused Products
Abstract
The invention provides a fast variable optical attenuator including a reflective membrane that serves as a varifocal mirror. Electrostatic deflection of the mirror defocuses the optical system and attenuates an optical signal launched to the mirror from an input port to an output port. Since the mirror is generally limited to deflections less than 1 micron, fast attenuation within a small (<5 dB) dynamic range is achieved. The dynamic range is improved by combining the fast attenuator with a slower attenuator. In the preferred embodiment, the slow and fast attenuator are not coupled via optical waveguides, but rather are optically coupled via free space or are integrated in the same device. Advantageously, this compact arrangement reduces the excess loss associated with optical fiber coupling and lowers packaging costs.
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Citations
15 Claims
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1. An optical attenuator comprising:
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an input port and an output port;
a deformable membrane having a reflective surface disposed to reflect light launched from the input port substantially towards the output port, the membrane supported by a frame having a radially symmetric opening; and
deforming means for controllably deflecting the membrane into the opening such that the reflective surface forms a concave mirror having a concavity that determines the optical coupling efficiency between the input and output ports. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A variable optical attenuator comprising:
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a first attenuator having a dynamic range less than about 10 dB and a response time of less than about one microsecond; and
a second attenuator having a dynamic range greater than about 10 dB at a response time greater than about one millisecond, wherein the first and second attenuators are optically coupled in series. - View Dependent Claims (15)
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Specification