Mars optical modulators
First Claim
Patent Images
1. An electrooptic device comprising:
- (a) a substrate having a refractive index η
, and having at least two layers (i) and (ii) on the surface thereof, wherein(i) is a layer having a thickness t1 greater than 50 Angstroms, and an index of refraction approximately equal to η
1/2, and(ii) is a layer with a refractive index η
, and a thickness t2,(b) a membrane having an optically transparent portion and comprising at least two layers (iii) and (iv), whereinlayer (iii) is a layer with a refractive index η
, and a thickness t3, andlayer (iv) is a layer with a refractive index approximately equal toη
1/2, and a thickness t4, where t4 is greater than 50 Angstroms,(c) means for directing a beam of light on said optically transparent portion of said membrane, said light having a wavelength λ
, where λ and
t1 and t4 are related by;
space="preserve" listing-type="equation">t.sub.1 =(λ
/4η
.sup.1/2)t.sub.4(d) a flexible support for positioning the optically transparent portion of said membrane at a first position spaced from said substrate and defining an air gap d1 between said layer (ii) and said layer (iii), and a second position spaced from said substrate defining an air gap d2 between said layer (ii) and layer (iii), and(e) means for applying an electrical bias across said air gap to optically switch said optically transparent portion of said membrane from said first position to said second position.
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Abstract
The specification describes a double poly Mechanical Anti-Reflection Switch (MARS) device in which transition layers of SiNx are provided on either side of the air gap, and the thickness ratio of the two transition layers is adjusted to provide a tradeoff between the insertion loss of the device and the optical bandwidth.
165 Citations
20 Claims
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1. An electrooptic device comprising:
-
(a) a substrate having a refractive index η
, and having at least two layers (i) and (ii) on the surface thereof, wherein(i) is a layer having a thickness t1 greater than 50 Angstroms, and an index of refraction approximately equal to η
1/2, and(ii) is a layer with a refractive index η
, and a thickness t2,(b) a membrane having an optically transparent portion and comprising at least two layers (iii) and (iv), wherein layer (iii) is a layer with a refractive index η
, and a thickness t3, andlayer (iv) is a layer with a refractive index approximately equal to η
1/2, and a thickness t4, where t4 is greater than 50 Angstroms,(c) means for directing a beam of light on said optically transparent portion of said membrane, said light having a wavelength λ
, where λ and
t1 and t4 are related by;
space="preserve" listing-type="equation">t.sub.1 =(λ
/4η
.sup.1/2)t.sub.4(d) a flexible support for positioning the optically transparent portion of said membrane at a first position spaced from said substrate and defining an air gap d1 between said layer (ii) and said layer (iii), and a second position spaced from said substrate defining an air gap d2 between said layer (ii) and layer (iii), and (e) means for applying an electrical bias across said air gap to optically switch said optically transparent portion of said membrane from said first position to said second position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for modulating light comprising:
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(a) directing a beam of light with a wavelength λ
on a substrate, said substrate having a refractive index η
, and having at least two layers (i) and (ii) thereon, wherein;(i) is a layer with a thickness t1, and a refractive index approximately equal to η
1/2,(ii) is a layer with a refractive index η
, and a thickness approximately equal to λ
/4η
,(b) providing a membrane spaced from said substrate, said membrane having an optically transparent portion and comprising at least two layers (iii), and (iv), wherein layer (iii) is a layer with a refractive index η
, and a thickness approximately equal to λ
/4η
,layer (iv) is a layer with a refractive index approximately equal to η
1/2, and a thickness t2, wherein;
space="preserve" listing-type="equation">t.sub.1 =(λ
/4η
.sup.1/2)-t.sub.2(c) providing a flexible support for positioning said optically transparent portion of said membrane at a first position spaced from said substrate and defining an air gap d1 between said layers (ii) and (iii), and a second position spaced from said substrate defining an air gap d2 between said layers (ii) and (iii), and (d) applying an electrical bias across said air gap to switch said optically transparent portion of said membrane from said first position to said second position. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for fabricating an electrooptic modulator comprising the steps of:
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a. depositing a first dielectric layer having a thickness t1 on a semiconductor substrate, b. depositing a first polysilicon layer on said first dielectric layer, c. depositing a glass layer on said first polysilicon layer, d. depositing a second polysilicon layer on said glass layer, e. depositing a second dielectric layer with a thickness t2 on said second polysilicon layer, said dielectric layer selected from the group consisting of silicon dioxide and silicon nitride, and wherein t1 +t2 equal approximately 2077 μ
m,f. masking said dielectric layer with a photomask having a central membrane feature and at least three arms extending from said central membrane feature to a peripheral frame, leaving exposed portions corresponding with spaces between said arms, g. etching through said dielectric layer and said second polysilicon layer using a plasma etch and using said photomask as an etch mask, to form openings corresponding with said spaces between said arms and expose portions of said glass layer in said openings, and h. etching through said glass layer in said exposed portions and under said arms using a wet etchant, thereby forming an air gap between said insulating layer and said central membrane feature and leaving said central membrane feature supported by said arms. - View Dependent Claims (20)
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Specification