Photonic crystal fibres
AssigneeCrystal Fibre A/S
InventorsPhilip St. John Russell, Timothy Adam Birks, Jonathan Cave Knight
Life of this patent
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Abstract
A photonic crystal fiber comprising a bulk material having an arrangement of longitudinal holes (130, 140) and a guiding core (135), wherein the fiber has at-most-two-fold rotational symmetry about a longitudinal axis and as a result of that lack of symmetry, the fiber is birefringent.
Claims48
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, wherein the fibre has two-fold and at-most-two-fold rotational symmetry about a longitudinal axis of the fibre, wherein the symmetry of the fibre is arranged to render the fibre birefringent, in which the birefringence is such that light with a wavelength of 1.5 microns propagating in the fibre has a beat length of less than 1 cm, or if the fibre does not guide light at 1.5 microns, a beat length, at a guided wavelength, that scales up or down to a beat length at 1.5 microns.
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, wherein the fibre has at-most-two-fold rotational symmetry about a longitudinal axis of the fibre, and as a result of the symmetry, of the fibre is birefringent, in which the birefringent fibre has stress birefringence.
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, wherein the fibre has at-most-two-fold rotational symmetry about a longitudinal axis of the fibre, and as a result of the symmetry, the fibre is birefringent, in which the lack of higher rotational symmetry results from a variation across the cross-section of the fibre, in one of the following in combination with one or more of the following or with a variation in another parameter:
- the microstructure of the core, the diameter of the holes, the bulk material, the material contained in the holes, and the shape of the holes.
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, wherein the fibre has at-most-two-fold rotational symmetry about a longitudinal axis of the fibre, and as a result of the symmetry, of the fibre is birefringent, in which the birefringent fibre has form birefringence.
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, wherein the fibre has two-fold rotational symmetry about a longitudinal axis wherein the fibre has a sufficient short beat length to render the fibre birefringent.
A photonic crystal fibre comprising a bulk material having an arrangement of longitudinal holes and a guiding core, the fibre has two-fold rotational symmetry about a longitudinal axis of the fibre wherein the two-fold rotational symmetry arrangement of the fibre render the fibre birefringent.
A photonic crystal fibre having a longitudinal axis circumscribed by a guiding core, which is surrounded by a cladding, the fibre comprises an arrangement of a plurality of longitudinal, parallel holes, wherein the fibre has two-fold and at-most-two-fold rotational symmetry about the longitudinal axis of the fibre wherein the symmetry of the fibre is arranged to render the fibre birefringent.
A method of producing a birefringent photonic crystal fibre, the method comprising the following steps:
- (a) forming a stack of canes, at least some of which are capillaries, the stack including canes arranged to form a core region in the fibre and canes arranged to form a cladding region in the fibre;
- and
- (b) drawing the stack of canes into a birefringent fibre which has at-most-two-fold rotational symmetry about any longitudinal axis,
- in which the stack of canes is arranged to have at-most-two-fold rotational symmetry about a longitudinal axis of the stack.
A method of producing a photonic crystal fibre, comprising:
- (a) providing a plurality of elongate canes, each having a longitudinal axis, a first end and a second end, at least some of the canes being capillaries each having a hole parallel to the longitudinal axis of the cane and running from the first end of the cane to the second end of the cane;
- (b) forming the canes into a stack, the canes being arranged with their longitudinal axes substantially parallel to each other and to the longitudinal axis of the stack;
- (c) drawing the stack into a fibre whilst maintaining the hole of at least one capillary in communication with a source of fluid at a first pressure whilst maintaining the pressure around the capillary at a second pressure that is different from the first pressure, wherein the hole at the first pressure becomes, during the drawing process, a size different from that which it would have become without the pressure difference.
A method of producing a birefringent photonic crystal fibre, the method comprising the following steps:
- (a) forming a stack of canes, at least some of which are capillaries, the stack including canes arranged to form a core region in the fibre and canes arranged to form a cladding region in the fibre;
- and
- (b) drawing the stack of canes into a birefringent fibre which has at-most-two-fold rotational symmetry about any longitudinal axis, in which the birefringence results at least partly from stresses formed within the fibre as it is drawn.
Dependencies are inferred from the claim text.