Crosstalk-reduced integrated digital optical switch
First Claim
1. A method of reducing crosstalk in an optical switch having a first branch and a second branch, each of the first and second branches including a refraction-controlled section and an absorption-controlled section, the method including the steps of:
- selecting one of the first and second branches as part of a desired optical signal path through the switch, such that one of the first and second branches is a selected branch and the other is a non-selected branch;
configuring the absorption-controlled section of the selected branch into a first absorption state providing a first level of absorption and no substantial gain for the optical signal; and
configuring the absorption-controlled section of the non-selected branch into an second absorption state providing a second level of absorption greater than the first level of absorption.
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Accused Products
Abstract
Methods and apparatus for performing optical signal switching or other optical routing functions in an optical device or system, in which crosstalk induced by modal interference is suppressed by providing appropriate loss, gain and/or refractive index changes in different parts of a switch structure. An exemplary optical signal switch includes first and second branches each having a refraction-controlled section and an absorption-controlled section. An optical signal path over which an optical signal propagates in passing through the switch is selected to include a portion of at least one of the first and second branches, such that one of the first and second branches is a selected branch and the other branch is a non-selected branch. The refraction-controlled section of the selected branch is configured in a high effective refractive index state which allows the optical signal to propagate along at least a portion of the selected branch, while the refraction-controlled section of the non-selected branch is configured in a low effective refractive index state. The absorption-controlled section of the selected branch is configured in a low absorption state, while the absorption-controlled section of the non-selected branch is configured in a high absorption state to reduce crosstalk within the optical switch. An effective refractive index in a given refraction-controlled section may be provided using electro-refractive techniques such as the quantum-confined Stark effect (QCSE) or the Franz-Keldysh effect, or by carrier-induced effects such as carrier injection or carrier depletion. An absorption change in a given absorption-controlled section may be provided using electro-absorptive techniques or a gain-switching technique. The switch may be configured as a Y-branch switch, a directional coupler, or in other suitable configurations, and may be interconnected with other similar switches to construct 1×N, N×1, N×M and N×N switch arrays.
90 Citations
46 Claims
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1. A method of reducing crosstalk in an optical switch having a first branch and a second branch, each of the first and second branches including a refraction-controlled section and an absorption-controlled section, the method including the steps of:
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selecting one of the first and second branches as part of a desired optical signal path through the switch, such that one of the first and second branches is a selected branch and the other is a non-selected branch; configuring the absorption-controlled section of the selected branch into a first absorption state providing a first level of absorption and no substantial gain for the optical signal; and configuring the absorption-controlled section of the non-selected branch into an second absorption state providing a second level of absorption greater than the first level of absorption. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An optical switch comprising:
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first and second branches each having a refraction-controlled section and an absorption-controlled section; and an optical signal path over which an optical signal propagates in passing through the switch, the optical signal path including a portion of at least one of the first and second branches, such that one of the first and second branches is a selected branch and the other branch is a non-selected branch, wherein the absorption-controlled section of the selected branch is configured in a first absorption state providing a first level of absorption and no substantial gain for the optical signal, and the absorption-controlled section of the non-selected branch is configured in a second absorption state providing a second level of absorption greater than the first level of absorption. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An optical switch comprising:
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a region of refraction-control material formed on a substrate; a region of absorption-control material formed on the substrate adjacent to the region of refraction-control material; and first and second switch branches, each having a refraction-controlled section associated with the refraction-control material region and an absorption-controlled section associated with the absorption-control material region, such that in configuring a given optical path through at least a portion of the switch, one of the first and second branches is configured as a selected branch and the other branch as a non-selected branch, wherein the absorption-controlled section of the selected branch is configured to provide a first level of absorption and no substantial gain for the optical signal, and the absorption-controlled section of the non-selected branch is configured to provide a second level of absorption greater than the first level of absorption. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. An optical switch array comprising:
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a plurality of optical switches, at least a subset of the optical switches each having first and second branches, with each of the first and second branches having a refraction-controlled section and an absorption-controlled section; and an optical signal path over which an optical signal propagates in passing through at least a portion of the switch array, the optical signal path including a portion of at least one of the first and second branches of a given switch, such that one of the first and second branches of the given switch is a selected branch and the other branch is a non-selected branch, wherein the absorption-controlled section of the selected branch is configured in a first absorption state providing a first level of absorption and no substantial gain for the optical signal, and the absorption-controlled section of the non-selected branch is configured in a second absorption state providing a second level of absorption greater than the first level of absorption. - View Dependent Claims (39, 40, 41, 42)
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43. A method of reducing crosstalk in an optical switch having a first branch and a second branch, each of the first and second branches including a refraction-controlled section and an absorption-controlled section, the method including the steps of:
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selecting one of the first and second branches as part of a desired optical signal path through the switch, such that one of the first and second branches is a selected branch and the other is a non-selected branch; configuring the absorption-controlled section of the selected branch into a first absorption state providing a first level of absorption; and configuring the absorption-controlled section of the non-selected branch into an second absorption state providing a second level of absorption greater than the first level of absorption, wherein at least one of the absorption-controlled sections of the selected and non-selected branches operates using an electro-absorptive technique.
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44. An optical switch comprising:
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first and second branches each having a refraction-controlled section and an absorption-controlled section; and an optical signal path over which an optical signal propagates in passing through the switch, the optical signal path including a portion of at least one of the first and second branches, such that one of the first and second branches is a selected branch and the other branch is a non-selected branch, wherein the absorption-controlled section of the selected branch is configured in a first absorption state providing a first level of absorption, and the absorption-controlled section of the non-selected branch is configured in a second absorption state providing a second level of absorption greater than the first level of absorption, and further wherein at least one of the absorption-controlled sections of the selected and non-selected branches operates using an electro-absorptive technique.
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45. An optical switch comprising:
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a region of refraction-control material formed on a substrate; a region of absorption-control material formed on the substrate adjacent to the region of refraction-control material; and first and second switch branches, each having a refraction-controlled section associated with the refraction-control material region and an absorption-controlled section associated with the absorption-control material region, such that in configuring a given optical path through at least a portion of the switch, one of the first and second branches is configured as a selected branch and the other branch as a non-selected branch, wherein the absorption-controlled section of the selected branch is configured to provide a first level of absorption, and the absorption-controlled section of the non-selected branch is configured to provide a second level of absorption greater than the first level of absorption, and further wherein at least one of the absorption-controlled sections of the selected and non-selected branches operates using an electro-absorptive technique.
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46. An optical switch array comprising:
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a plurality of optical switches, at least a subset of the optical switches each having first and second branches, with each of the first and second branches having a refraction-controlled section and an absorption-controlled section; and an optical signal path over which an optical signal propagates in passing through at least a portion of the switch array, the optical signal path including a portion of at least one of the first and second branches of a given switch, such that one of the first and second branches of the given switch is a selected branch and the other branch is a non-selected branch, wherein the absorption-controlled section of the selected branch is configured in a first absorption state providing a first level of absorption, and the absorption-controlled section of the non-selected branch is configured in a second absorption state providing a second level of absorption greater than the first level of absorption, and further wherein at least one of the absorption-controlled sections of the selected and non-selected branches operates using an electro-absorptive technique.
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Specification