| 摘要 |
The invention is directed to an improved wavelength selective optical filter component having an optical path therethrough and comprising a first and a second optical port, a multimode interference region and a wavelength selective element. The first optical port and the multimode interference region each have an axis of symmetry relative to the optical path. The optical path enables light to travel through the multimode interference region and the wavelength selective element from the first or second optical port to the other optical port, and wherein the axis of symmetry of the multimode interference region is not aligned with the axis of symmetry of the first optical port. An advantage of arranging the multimode interference region and first optical port such that their axes of symmetry are not aligned is that this introduces a slope in the pass band of the device which can be chosen at the design stage to meet a specific slope requirement or can be used to cancel a pre-existing slope to give a resultant flat pass band.
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