ARROW waveguide: Difference between revisions
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In [[optics]], an '''anti-resonant reflecting optical waveguide''' ('''ARROW''') is formed from an anti-resonant [[Fabry-Perot]] reflector. The optical mode is leaky, but relatively low-loss propagation can be achieved by making the Fabry-Perot reflector of sufficiently high quality or small size. |
In [[optics]], an '''anti-resonant reflecting optical waveguide''' ('''ARROW''') is formed from an anti-resonant [[Fabry-Perot]] reflector. The optical mode is leaky, but relatively low-loss propagation can be achieved by making the Fabry-Perot reflector of sufficiently high quality or small size. |
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ARROWs can be realized as cylindrical waveguides (2D confinement) or slab waveguides (1D confinement). |
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The latter ARROWs are practically formed by a low index layer, embedded between higher index layers. Note that the refractive indices of are reversed, when comparing to usual waveguides. Light is confined by [[total internal reflection]] (TIR) on the inside of the higher index layers, but achieves a lot of modal overlap with the lower index central volume. |
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This strong overlap can be made plausible in a simplified picture imagining "rays", as in [[geometrical optics]]. Such rays are refracted into a very shallow angle, when entering the low index inner layer. Thus, one can use the metaphor that these rays "stay very long inside" the low index inner layer. Note this is just a methophor and the explanatory power of ray optics is very limited for the micrometer scales, at which these ARROWs are typically made. |
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ARROW structures are often used for guiding light in liquids, particularly in microfluidic systems. This is due to the difficulty of finding suitable optical cladding materials, with a lower refractive index than the liquid, which would be required to form a conventional waveguide structure. |
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==See also== |
==See also== |
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Revision as of 05:44, 26 February 2009
In optics, an anti-resonant reflecting optical waveguide (ARROW) is formed from an anti-resonant Fabry-Perot reflector. The optical mode is leaky, but relatively low-loss propagation can be achieved by making the Fabry-Perot reflector of sufficiently high quality or small size.
ARROWs can be realized as cylindrical waveguides (2D confinement) or slab waveguides (1D confinement). The latter ARROWs are practically formed by a low index layer, embedded between higher index layers. Note that the refractive indices of are reversed, when comparing to usual waveguides. Light is confined by total internal reflection (TIR) on the inside of the higher index layers, but achieves a lot of modal overlap with the lower index central volume.
This strong overlap can be made plausible in a simplified picture imagining "rays", as in geometrical optics. Such rays are refracted into a very shallow angle, when entering the low index inner layer. Thus, one can use the metaphor that these rays "stay very long inside" the low index inner layer. Note this is just a methophor and the explanatory power of ray optics is very limited for the micrometer scales, at which these ARROWs are typically made.
ARROW structures are often used for guiding light in liquids, particularly in microfluidic systems. This is due to the difficulty of finding suitable optical cladding materials, with a lower refractive index than the liquid, which would be required to form a conventional waveguide structure.
See also
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