ANGLED FIBER FERRULE HAVING OFF-AXIS FIBER THROUGH-HOLE AND METHOD OF COUPLING AN OPTICAL FIBER AT AN OFF-AXIS ANGLE
An angle-polished optical fiber may be mounted relative to a laser at an off-axis angle to allow coupled light from a laser to be substantially aligned with the axis of the fiber core. An angled fiber ferrule may facilitate providing the off-axis angle when coupling the angle-polished optical fiber to a laser package. The angled fiber ferrule includes a through hole including at least a portion that is off-axis. The axis of the off-axis portion of the through hole is angled at the off-axis angle with respect to an axis of the ferrule body portion.
1 . An angled fiber ferrule for use with an optical fiber having an end face angled at a fiber end angle (α) with respect to a plane normal to an axis of the fiber, the angled fiber ferrule comprising:
a ferrule body portion having a first end and a second end, the ferrule body portion defining a through-hole extending from the first end to the second end and configured to receive the optical fiber, at least a portion of the through-hole being off-axis such that an axis of the off-axis portion of the through-hole is angled at an off-axis angle (θ) with respect to a ferrule axis of the ferrule body portion.
2 . The angled fiber ferrule of claim 1 wherein the off-axis angle (θ) is determined according to the equation
θ
≈
α
(
n
f
n
a
-
1
)
,
wherein α is the fiber end angle, n f is the index of refraction of the fiber, and n a is the index of refraction of a medium from which the light is coupled into the fiber.
3 . The angled fiber ferrule of claim 1 wherein the ferrule body portion is made of metal.
4 . The angled fiber ferrule of claim 1 wherein the ferrule body portion is made of glass or ceramic.
5 . The angled fiber ferrule of claim 1 wherein the ferrule body portion is substantially cylindrical.
6 . The angled fiber ferrule of claim 1 wherein the ferrule body portion is configured to be coupled to a transistor outline (TO) can laser package housing.
7 . The angled fiber ferrule of claim 1 wherein the ferrule body portion is configured to be coupled to a butterfly laser package housing.
8 . The angled fiber ferrule of claim 1 wherein the ferrule body portion includes at least an inner portion of ceramic or glass and an outer portion of metal.
9 . The angled fiber ferrule of claim 1 wherein the off-axis portion of the through hole extends from the first end to the second end.
10 . The angled fiber ferrule of claim 1 wherein the through-hole includes an on-axis portion and an off-axis portion.
11 . An optical fiber coupling comprising:
an optical fiber having an end face angled at a fiber end angle (α) with respect to a plane normal to an axis of the fiber, the end face being configured to receive light coupled into the optical fiber; and
an angled fiber ferrule including a ferrule body portion having a first end and a second end, the ferrule body portion defining a through-hole extending from the first end to the second end and configured to receive the optical fiber, at least a portion of the through-hole being off-axis such that an axis of the off-axis portion of the through-hole is angled at an off axis angle (θ) with respect to a ferrule axis of the ferrule body portion.
12 . The optical fiber coupling of claim 11 wherein the off-axis angle (θ) provides a refraction of light coupled into the optical fiber such that light is coupled into the fiber refracts to a path substantially parallel to the axis of the fiber.
13 . The optical fiber coupling of claim 11 wherein the off-axis angle (θ) is determined according to the equation
θ
≈
α
(
n
f
n
a
-
1
)
,
wherein α is the fiber end angle, n f is the index of refraction of the fiber, and n a is the index of refraction of a medium from which the light is coupled into the fiber.
14 . The optical fiber coupling of claim 11 wherein the off-axis portion of the through hole extends from the first end to the second end.
15 . The optical fiber coupling of claim 11 wherein the through-hole includes an on-axis portion and an off-axis portion.
16 . The optical fiber coupling of claim 11 wherein the ferrule body portion includes at least an inner portion and an outer portion.
17 . A laser package for use with an optical fiber having an end face angled at a fiber end angle (α) with respect to a plane normal to an axis of the fiber, the laser package comprising:
a laser package housing including a ferrule mounting portion;
a laser mounted within the laser package housing; and
an angled fiber ferrule configured to be mounted in the ferrule mounting portion of the laser package housing, the angled fiber ferrule including a ferrule body portion having a first end and a second end, the ferrule body portion defining a through-hole extending from the first end to the second end and configured to receive the optical fiber, at least a portion of the through-hole being off-axis such that an axis of the off-axis portion of the through-hole is angled at an off-axis angle (θ) with respect to a ferrule axis of the ferrule body portion such that light from the laser is coupled into the optical fiber substantially aligned with an axis of the fiber.
18 . The laser package of claim 17 wherein the off-axis angle (θ) is determined according to the equation
θ
≈
α
(
n
f
n
a
-
1
)
,
wherein α is the fiber end angle, n f is the index of refraction of the fiber, and n a is the index of refraction of a medium from which the light is coupled into the fiber.
19 . A method of mounting an angle-polished optical fiber to a laser, the angle-polished fiber having an end face angled at a fiber end angle (α) with respect to a plane normal to an axis of the fiber, the method comprising:
positioning a portion of the angle-polished optical fiber in a through-hole of an angled fiber ferrule, at least a portion of the through-hole being off-axis such that an axis of the off-axis portion of the through-hole is angled at the off-axis angle (θ) with respect to a ferrule axis of the angled fiber ferrule; and
mounting the angled fiber ferrule to a laser package, wherein the off-axis angle of the through hole causes the angle-polished optical fiber to be positioned relative to the laser in an off-axis position such that an axis of the optical fiber is angled at the off-axis angle (θ) relative to a direction of emitted light from the laser being coupled into the fiber.
20 . The method of claim 19 wherein the off-axis angle (θ) provides a refraction of the light coupled into the optical fiber such that light is coupled into the fiber refracts to a path substantially parallel to the axis of the fiber.
21 . The method of claim 19 wherein the off-axis angle (θ) is determined according to the equation
θ
≈
α
(
n
f
n
a
-
1
)
,
wherein α is the fiber end angle, n f is the index of refraction of the fiber, and n a is the index of refraction of a medium from which the light is coupled into the fiber.
22 - 23 . (canceled)