High germanium content waveguide materials
First Claim
1. A glass composition comprising:
- a germanium-silicon oxynitride having a Ge/(Si+Ge) mole ratio of from about 0.25 to about 0.47 and an N/(N+O) mole ratio of less than about 0.1.
1 Assignment
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Accused Products
Abstract
Germanium-silicon oxide, germanium-silicon oxynitride and silica-germania-titania materials and oxynitride materials suitable for fabricating optical waveguides for liquid crystal based cross-connect optical switching devices have a refractive index of from about 1.48 to about 1.52 at 1550 nm, and a coefficient of thermal expansion at room temperature of from about 3×10−6° C.−1 to about 4.4×10−6° C.−1. The compositions are adjusted so that the refractive index of the germanium-silicon oxide, germanium-silicon oxynitride or silica-germania-titania material is closely matched to the refractive index of a typical liquid crystal material whereby improved optical performance of a liquid crystal based cross-connect optical switching device is achieved. The coefficient of thermal expansion of the germanium-silicon oxide, germanium-silicon oxynitride, or silica-germania-titania material is closely matched to the coefficient of thermal expansion of silicon, whereby strain induced birefringence caused by thermal stresses is reduced or avoided.
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Citations
19 Claims
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1. A glass composition comprising:
a germanium-silicon oxynitride having a Ge/(Si+Ge) mole ratio of from about 0.25 to about 0.47 and an N/(N+O) mole ratio of less than about 0.1. - View Dependent Claims (2, 3, 4, 16)
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5. A planar optical device comprising:
a waveguide core and waveguide cladding, wherein at least one of the waveguide core and the waveguide cladding is a germanium-silicon oxynitride glass having a Ge/(Si+Ge) mole ratio of from about 0.25 to about 0.47 and an N/(N+O) mole ratio of less than about 0.1. - View Dependent Claims (6, 7, 8, 17)
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9. A method of forming a planar optical device on a silicon substrate, wherein the device includes a waveguide baying a refractive index of from about 1.48 to about 1.52 at 1550 nm, and a coefficient of thermal expansion of from about 3×
- 10−
6°
C.−
1 to about 4.4×
10−
6°
C.−
1, comprising;depositing on a silicon substrate by plasma enhanced chemical vapor deposition a germanium-silicon oxide or oxynitride cladding layer having a Ge/(Si+Ge) mole ratio of from about 0.25 to about 0.47 and an N/(N+O) mole ratio of 0 to about 0.1;
depositing on the cladding layer by plasma enhanced chemical vapor deposition a germanium-silicon oxide or oxynitride core layer having a Ge/(Si+Ge) mole ratio of from about 0.25 to about 0.47 and an N/(N+O) mole ratio of 0 to about 0.1, wherein the refractive index of the core layer is higher than the refractive index of the cladding layer. - View Dependent Claims (10, 11)
- 10−
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12. A planar optical device comprising:
a waveguide core and waveguide cladding, wherein at least one of the waveguide core and the waveguide cladding is a silica-germania-titania glass having a Ge/(Si+Ge+Ti) mole ratio of from about 0.08 to about 0.17 and a Ti/(Si+Ge+Ti) mole ratio of less than about 0.08. - View Dependent Claims (13, 14, 18, 19)
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15. A method of forming a planar optical device on a silicon substrate, comprising:
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depositing on a silicon substrate by plasma enhanced chemical vapor deposition a silica-germania-titania cladding layer having a Ge/(Si+Ge+Ti) mole ratio of from about 0.08 to about 0.17 and a Ti/(Si+Ge+Ti) mole ratio of 0 to about 0.08; and
depositing on the cladding layer by plasma enhanced chemical vapor deposition a silica-germania-titania core layer having Ge/(Si+Ge+Ti) mole ratio of from about 0.08 to about 0.17 and a Ti/(Si+Ge+Ti) mole ratio of from 0 to about 0.08, wherein the refractive index of the come layer is higher than the refractive index of the cladding layer, wherein the device includes a waveguide having a refractive index of from about 3×
10−
6°
C.−
1 to about 4.4×
10−
6°
C.−
1.
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Specification