| 摘要 |
An optical fibre filter (1, 1') comprises a dual-mode optical fibre (2) which includes a core (3) and a cladding (4) and through which an optical signal can pass; a pair of coupling regions (8, 9) formed in the optical fibre (2) at a predefined mutual distance (L) so as to produce a power transfer between a first and a second propagation modes (LP01, LP11) of the optical signal; and a phase shift region (10) defined by a section of the fibre (2) lying between the coupling regions (8, 9), for producing a phase shift between the first and second propagation modes (LP01, LP11); in which, in the coupling regions (8, 9), the optical fibre (2) has, in cross section, an asymmetrical refractive index profile. <IMAGE> |
