| 摘要 |
<p>An optical fibre (20) is disclosed, the fibre is adapted in a manner such that it guides an optical signal substantially only in one non-degenerate mode, wherein an electro-magnetic field carrying the optical signal is symmetric with respect to rotation about the fibre axis. Preferably, the non-degenerate mode is the TE01 mode. In one embodiment, the optical fibre (20) includes a central hole region (22) surrounded by a concentric guiding region (24), which is in turn surrounded by a concentric cladding region 826). The guiding region (24) may comprise a Bragg reflector region. Through appropriate selection of design parameters of the fibre (20), the effective refractive index for the TM01 mode can be reduced relative to the TE01 mode to make it below a refractive index of the cladding region (269, resulting in leaking of the TM01 mode into the cladding region (26).</p> |
