| 摘要 |
The grating includes an optical waveguide core (2) and a sleeve (3) surrounding the core in an interaction zone (11). The interaction zone comprises a grating (19) which is intended to couple at least one mode which is guided by the core into at least one mode in the sleeve, or the reverse. The grating includes an optical waveguide core (2) and an optical sleeve (3, 3a, 3b, 3c, 3d) which is independent of the core, but which surrounds a portion of the core in an interaction zone (11). The interaction zone comprises a grating (19) which is intended to couple at least one mode which is guided by the core into at least one mode in the sleeve, or the reverse. The interaction zone provides a variation in coupling along the direction of propagation (z) of the optical modes. The refractive index of the sleeve is different from the refractive index of the substrate, and is less than the refractive index of the core - at least in the part of the core which forms the interaction zone.
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