Double-cavity micromechanical optical modulator with plural multilayer mirrors
First Claim
1. A modulator for modulating an optical signal comprising:
- a conductive substrate;
at least three multilayer mirrors disposed on said substrate, said mirrors being spaced apart from one another to define upper and lower optical cavities, said lower cavity having a fixed thickness approximately equal to a multiple of one-half of a wavelength of the optical signal, as measured within said lower cavity, said upper cavity being formed by an airgap having a variable thickness that in a first state is approximately equal to a multiple of one-half of a wavelength of the optical signal, as measured within said upper cavity, wherein a total reflectivity of said multilayer mirrors approaches a minimum value when said upper cavity is in its first state, said multilayer mirror located above said airgap including;
a conductive membrane having an optically transparent portion;
a flexible support for positioning the membrane in a first position wherein, under the action of a bias, the membrane moves to a second position, changing said air gap by a fraction of a wavelength of the optical signal, as measured in air, where the change from the first to the second position causes a change from a minimum total reflectivity to a maximum total reflectivity state.
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Abstract
A mechanical modulator is provided that includes a conductive substrate and at least three multilayer mirrors disposed on the substrate. The mirrors are spaced apart from one another to define upper and lower optical cavities. The upper cavity is formed by an airgap having a variable thickness. The multilayer mirror located above the airgap includes a conductive membrane having an optically transparent portion and a flexible support for orienting the membrane in a first position. Under the action of a bias, the membrane moves to a second position, changing the air gap by a fraction of a wavelength of the optical signal, as measured in air. The change in position of the membrane from the first to the second position causes a change in the total reflectivity of the modulator from a minimum to a maximum value.
266 Citations
13 Claims
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1. A modulator for modulating an optical signal comprising:
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a conductive substrate; at least three multilayer mirrors disposed on said substrate, said mirrors being spaced apart from one another to define upper and lower optical cavities, said lower cavity having a fixed thickness approximately equal to a multiple of one-half of a wavelength of the optical signal, as measured within said lower cavity, said upper cavity being formed by an airgap having a variable thickness that in a first state is approximately equal to a multiple of one-half of a wavelength of the optical signal, as measured within said upper cavity, wherein a total reflectivity of said multilayer mirrors approaches a minimum value when said upper cavity is in its first state, said multilayer mirror located above said airgap including; a conductive membrane having an optically transparent portion; a flexible support for positioning the membrane in a first position wherein, under the action of a bias, the membrane moves to a second position, changing said air gap by a fraction of a wavelength of the optical signal, as measured in air, where the change from the first to the second position causes a change from a minimum total reflectivity to a maximum total reflectivity state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification