| 摘要 |
An optical filter (300) comprises a multimode waveguide (326), and first (322) and second (324) coupling waveguides which communicate with the multimode waveguide at respective ends thereof. Filtering is achieved by the effect of self-imaging in the multimode waveguide. The filter further comprises one or ore series of apertures (314A, 314B, 314C) within the multimode waveguide, the or each series being located at a longitudinal position within the multimode waveguide at which 1-to-N way intensity division of an input optical field occurs, the optical field being the lowest order transverse mode of the coupling waveguides. The (one or more) series of apertures reduces the transmission of the filter at wavelengths other than those corresponding to transmission peaks of the filter's transmission function, thus providing improved filtering performance compared to prior art optical filters based on self-imaging. |
