Anti-waveguide routing structure
First Claim
1. A method for switching an optical switch from a first state to a second state, said optical switch including a structure which in said first state provides confinement against propagation of an optical mode in at least a first direction out of a confinement region,comprising the step of reducing the refractive index of at least a first part of said confinement region to a value which is below the index of refraction of a first region of said switch outside of and adjacent to said confinement region in said first direction, while maintaining confinement in a second direction different from said first direction.
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Abstract
In a first state of an optical switch, a structure in the switch confines an optical mode to propagate along a first, unswitched path. The switch is switched into a second state by reducing the refractive index along the first path, or by increasing the refractive index of a region of the switch outside but adjacent to the first path, until the index within the first path is lower, preferably substantially lower, than that of the adjacent region. This creates an anti-waveguiding section in which light is forced to diverge from the unswitched path both by diffraction and refraction. The refractive index change is produced thermo-optically or electro-optically, for example. In a symmetric planar embodiment, upon actuation, light escapes from the confinement region into two beams deflected symmetrically in lateral directions while remaining vertically confined. In an asymmetric planar embodiment, upon actuation, light from the confinement region escapes in one direction away from the confinement region in the horizontal plane, while remaining confined vertically and in the opposite direction in the horizontal plane. A self-aligned method for fabricating optical switches is also described.
80 Citations
33 Claims
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1. A method for switching an optical switch from a first state to a second state, said optical switch including a structure which in said first state provides confinement against propagation of an optical mode in at least a first direction out of a confinement region,
comprising the step of reducing the refractive index of at least a first part of said confinement region to a value which is below the index of refraction of a first region of said switch outside of and adjacent to said confinement region in said first direction, while maintaining confinement in a second direction different from said first direction.
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15. Optical switch apparatus including structure comprising a confinement region, a first region outside of and adjacent to said confinement region in a first direction, and an applicator,
said structure having a first state in which said first part of said confinement region has a first state index of refraction, and in which said an optical mode traveling in said confinement region is confined against propagation in at least said first direction and a second direction different from said first direction, said structure further having a second state, entered in response to activation of said applicator, in which at least a first part of said confinement region has a refractive index which is below said first state index of refraction and further is below the index of refraction of said first region outside of and adjacent to said confinement region in said first direction, and in which confinement is maintained in said second direction.
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22. A method for switching an optical switch from a first state to a second state, said optical switch including a structure which provides vertical confinement of an optical mode to a confinement region, and which in said first state further confines said optical mode against propagation of said mode into a first lateral region laterally adjacent to said confinement region in a first lateral direction from said confinement region,
comprising the step of altering the refractive index profile of said switch such that a portion of said confinement region adjacent to said first lateral region has a lower refractive index than a portion of said first lateral region adjacent to said confinement region, while maintaining said vertical confinement of said optical mode.
Specification