Micromechanical modulator
First Claim
1. A modulator for modulating an optical signal comprising:
- a conductive substrate;
a conductive membrane comprising at least a first layer of material, the first layer having a refractive index which is approximately equal to the square root of the refractive index of the substrate, and a thickness approximately equal to one-quarter of a wavelength of the optical signal, as measured within the first layer, the membrane further having an optically transparent portion;
a flexible support for positioning the membrane in a first position wherein the membrane is oriented in spaced and superposed relation to the substrate, defining an air gap which is approximately equal to an integer multiple of one-quarter of a wavelength of the optical signal, as measured in air; and
a means for supplying bias;
where, under the action of bias, the membrane moves to a second position, changing the air gap by approximately one-quarter of a wavelength of the optical signal, as measured in air, where the change from the first to the second position causes a change in the amount of the optical signal that is reflected from the membrane.
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Accused Products
Abstract
A method and apparatus for modulating an optical signal using a micromechanical modulator are disclosed. The modulator comprises a membrane, which consists of at least one layer, and a substrate, spaced to form an air gap. The layers of the membrane are characterized in that there is a relationship between the refractive indices of the layers and the refractive index of the substrate. The membrane is suspended in a first position over the substrate by a flexible support arrangement. Bias is applied to the membrane and the substrate to create an electrostatic force to move the membrane towards the substrate to a second position. The reflectivity of the device to an optical signal changes as the membrane moves from the first position to the second position, thereby modulating the signal.
552 Citations
55 Claims
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1. A modulator for modulating an optical signal comprising:
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a conductive substrate; a conductive membrane comprising at least a first layer of material, the first layer having a refractive index which is approximately equal to the square root of the refractive index of the substrate, and a thickness approximately equal to one-quarter of a wavelength of the optical signal, as measured within the first layer, the membrane further having an optically transparent portion; a flexible support for positioning the membrane in a first position wherein the membrane is oriented in spaced and superposed relation to the substrate, defining an air gap which is approximately equal to an integer multiple of one-quarter of a wavelength of the optical signal, as measured in air; and a means for supplying bias; where, under the action of bias, the membrane moves to a second position, changing the air gap by approximately one-quarter of a wavelength of the optical signal, as measured in air, where the change from the first to the second position causes a change in the amount of the optical signal that is reflected from the membrane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A modulator for modulating an optical signal comprising:
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a conductive substrate; an optical fiber having a first end in optical communication with an optically transparent portion of a conductive membrane; the conductive membrane having a first and a second surface and comprising an optically active layer having a refractive index which is approximately equal to the square root of the product of the refractive indices of the conductive substrate and the optical fiber, and a thickness approximately equal to one-quarter of a wavelength of the optical signal, as measured within the optically active layer; and a means for supplying bias, wherein the first end of the optical fiber is in superposed relation to the first surface of the conductive membrane and is spaced from the first surface by approximately an integer multiple of one-quarter of a wavelength of the optical signal, as measured in air, and where the conductive substrate is oriented in superposed relation to the second surface of the conductive membrane and is spaced from the second surface by approximately an integer multiple of one-quarter of a wavelength of the optical signal, as measured in air, where the space between the second surface of the conductive membrane and the conductive substrate defines a first position of the conductive membrane, and where under the action of bias, the conductive membrane moves to a second position, changing the space between the second surface and the conductive substrate by approximately one-quarter of a wavelength of the optical signal, as measured in air, the change from the first to the second position causing a change in the amount of the optical signal that is reflected from the membrane.
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17. A device which, under the action of an applied bias, has a variable reflectivity to an incident optical signal received by the device, comprising:
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a substrate; a membrane comprising at least a first layer of material, the first layer having a refractive index which is approximately equal to the square root of the refractive index of the substrate, the membrane further having an optically transparent portion; and a flexible support for positioning the membrane in a first position wherein the membrane is oriented in spaced and superposed relation to the substrate to form an air gap. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A device which, under the action of an applied bias, has a variable reflectivity to an incident optical signal received by the device, comprising:
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a substrate; and an optical fiber having a first end in optical communication with an optically transparent portion of a membrane; the membrane having a first and a second surface and comprising at least a first layer having a refractive index which is approximately equal to the square root of the product of the refractive indices of the substrate and the optical fiber; wherein the first end of the optical fiber is in superposed and spaced relation to the first surface of the membrane, and where the substrate is oriented in superposed and spaced relation to the second surface of the membrane so that the membrane is positioned between the first end of the optical fiber and the substrate. - View Dependent Claims (41)
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42. A method for modulating an optical signal comprising:
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providing a conductive substrate; providing a conductive membrane in spaced and superposed relation to the substrate where the membrane comprises a layer of material having a refractive index which is approximately equal to the square root of the refractive index of the substrate, the membrane further having a first and second position; exposing the membrane to an optical signal; and applying a bias to move the membrane from the first position to the second position causing the reflectivity of the membrane to change. - View Dependent Claims (43, 44, 45)
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46. A method for modulating an optical signal, comprising the steps of:
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providing a device for modulating an optical signal comprising a membrane and a substrate in spaced, superposed relation, where the membrane comprises a layer of material having a refractive index which is approximately equal to the square root of the refractive index of the substrate, and where the membrane has a first position in the absence of a bias and a second position when bias is applied; exposing the device to an optical signal; and applying a bias to the device to move the membrane from the first position to the second position. - View Dependent Claims (47)
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48. A method for making a modulator for modulating an optical signal comprising:
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providing a conductive substrate; forming a conductive membrane on the substrate so that an air gap is defined between the membrane and a portion of the substrate, where the membrane comprises at least a first layer of material having a refractive index which is approximately equal to the square root of the refractive index of the substrate. - View Dependent Claims (49, 50, 51)
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52. A method for making a modulator for modulating an optical signal comprising:
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providing a conductive substrate; forming a conductive membrane on the substrate so that an air gap is defined between the membrane and a portion of the substrate, where the membrane comprises at least a first layer of material having a refractive index which is approximately equal to the square root of the product of the refractive indices of the substrate and the optical fiber; forming a support to support an optical fiber so that the optical fiber is spaced from the first layer of the membrane by approximately an integer multiple of one-quarter of a wavelength of the optical signal, as measured in air; and attaching the optical fiber to the support. - View Dependent Claims (53, 54, 55)
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Specification