Orientation switchable optical fibres

An orientation switchable optical fibre comprising an elongate body having two ends, which body is twisted intermediate the two ends, a central core region in which light carried by the fibre is confined, passive means extending substantially from the first end of the body to substantially the location of the twist, which passive means promotes orientation of light in at least one first transverse axis of the body, active means extending substantially from the location of the twist to substantially the second end of the body, which active means has a plurality of features each switchable between an off state in which the feature is ineffective and an on state in which the feature is effective to promote orientation of light in a corresponding second transverse axis of the body, wherein one of the second transverse axes is substantially aligned with a first of the first transverse axes and wherein in the on state of the one of the plurality of features corresponding to the said one of the second axes light remains confined in the said first axis along the length of the body and in the on state of the one of the other of the plurality of features light transits on passing the location of the twist from the said first axis to a second axis corresponding to the said one other of the plurality of features.

A method of switching light orientation in an optical fibre comprising an elongate body having two ends, which body is twisted intermediate the two ends, a central core region in which light carried by the fibre is confined, passive means extending substantially from one end to substantially the other end of the body, which passive means promotes orientation of light in at least one first transverse axis of the body, active means extending substantially from the location of the twist to substantially to the other end of the body, which active means is switchable between an off state in which the active means is ineffective and an on state in which the active means is effective to promote orientation of light in at least one second transverse axis of the body, the method comprising switching the active means between the off state in which light remains confined in the at least one first axis along the length of the body and the on state in which light transits on passing the location of the twist from the at least one first axis to the at least one second axis.

A method of switching light orientation in an optical fibre comprising an elongate body having two ends, which body is twisted intermediate the two ends, a central core region in which light carried by the fibre is confined, passive means extending substantially from the first end of the body to substantially the location of the twist, which passive means promotes orientation of light in at least one first transverse axis of the body, active means extending substantially from the location of the twist to substantially the second end of the body, which active means has a plurality of features each switchable between an off state in which the feature is ineffective and an on state in which the feature is effective to promote orientation of light in a corresponding transverse axis of the body, wherein one of the second transverse axes is substantially aligned with a first of the first transverse axes, the method comprising switching one of the plurality of features corresponding to the said one second axis light to an on state such that light remains confined in the said first axis along the length of the body and alternately switching one of the other of the plurality of features in to an on state such that light transits on passing the location of the twist from the said first axis to a second axis corresponding to the said one other of the plurality of features.