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Patent EP0206577A2 successfully refreshed from Google Patents.
EP0206577A2
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Optical fiber coupler
Assignee: Leland Stanford Junior University
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Filing: 1986-06-04
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Granted: —
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Expires: 2006-06-04
Abstract
Abstract A fiber optic coupler comprises a multimode fiber bus (42), an input branch fiber (44), and an output branch fiber (46). Coupling between the fibers is accomplished by means of a reflector (60), disposed in the core (42a) of the multimode optical fiber (42). The reflector (60) is quite small, such that only a small fraction of the light propagating in the mulfimode fiber (42) is incident thereon. The incident light is reflected towards the output branch fiber (46) and coupled thereto through a lens (56). Light propagating in the input branch fiber (44) towards the multimode fiber (42) is focused on the reflector (60) by means of a lens (52). The reflector (60) is oriented to reflect the focused light in a generally cone-shaped beam directed longitudinally down the axis of a muftimode fiber (42). Preferably, the cone-shaped beam diverges so that substantially all the modes within the acceptance cone of the multimode fiber are excited. Such excitation of the modes is preferably equalized by selecting the numerical aperture of the multimode fiber (42) such that only the portion of the reflected beam which has a relatively uniform intensity is within the acceptance cone of the fiber (42). The invention is particularly advantageous for local area networks and distributed sensor systems.
Inventors
- 👤 Kjell Blotekjaer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 17:41
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/2804; G02B6/2821; G02B6/2817
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
61 words
A fiber optic coupler, characterized by: a first optical fiber (44); a second, multimode optical fiber (42); and a reflector (60), substantially smaller than the core (42a) of said multimode optical fiber (42), said reflector (60) disposed within the core (42a) of said multimode optical fiber (42) and positioned to provide optical communication between said first and second fibers (44, 42).
Claim 2
Dependent Claim
61 words
A fiber optic coupler, characterized by: a first optical fiber (44); a second, multimode optical fiber (42); and a reflector (60), substantially smaller than the core (42a) of said multimode optical fiber (42), said reflector (60) disposed within the core (42a) of said multimode optical fiber (42) and positioned to provide optical communication between said first and second fibers (44, 42).
Claim 3
Dependent Claim
39 words
A fiber optic coupler, as defined by Claim 1, characterized in that said reflector (60) is positioned to receive light from said first optical fiber (44) and reflect the light for propagation in said second multimode optical fiber (42).
Claim 4
Dependent Claim
59 words
A fiber optic coupler, as defined by Claims 1 or 2, characterized in that said reflector (60) is sized to intercept only a small fraction of light propagating in said multimode fiber (42), and is positioned to reflect the light from said multimode fiber (42) to said first optical fiber (44) for propagation in said first optical fiber (44).
Claim 5
Dependent Claim
54 words
A fiber optic coupler, as defined by Claims 2 or 3, characterized in that said multimode fiber (42) includes plural mode groups, the reflector (60) and total reflection complementary angle of said multimode fiber (42) being relatively sized to cause substantially all of said plural mode groups to be excited with the reflected light.
Claim 6
Dependent Claim
61 words
A fiber optic coupler, as defined by Claim 4, characterized in that said reflector (60) and said total reflection complementary angle of said multimode fiber (42) are relatively sized to cause the reflected light to be distributed among said plural mode groups of said multimode fiber (42) substantially in proportion to the number of modes in each of said mode groups.
Claim 7
Dependent Claim
37 words
A fiber optic coupler, as defined by any of Claims 1 to 5, characterized in that said first optical fiber (44) is a single mode optical fiber which propagates light in a generally Gaussian shaped energy distribution.
Claim 8
Dependent Claim
50 words
A fiber optic coupler, as defined in Claim 6, characterized in that said reflector (60) is sized to receive only that portion (E ) of light propagating in said first fiber (44) which is within the peak of said energy distribution such that said reflector (60) is substantially uniformly illuminated.
Claim 9
Dependent Claim
40 words
A fiber optic coupler, as defined by any of Claims 1 to 7, additionally characterized by a third optical fiber (46), said reflector (60) additionally providing optical communication between said third optical fiber (46) and said second multimode fiber (42).
Claim 10
Dependent Claim
66 words
A fiber optic coupler, as defined by Claim 8, characterized in that said reflector (60) is positioned to reflect light from said first optical fiber (44) to said multimode fiber (42) for propagation in said multimode fiber (42), said reflector (60) additionally reflecting light from said multimode fiber (42) to said third optical fiber (46), for input to an end of said third optical fiber (46).
Claim 11
Dependent Claim
34 words
A fiber optic coupler, as defined by any of Claims 1 to 8, additionally characterized by a lens (52), disposed between said first and second optical fibers (44, 42), for focusing light propagating therebetween.
Claim 12
Dependent Claim
23 words
A fiber optic coupler, as defined by any of Claims 1 to 10, characterized in that said reflector (60) comprises a plane mirror.
Claim 13
Dependent Claim
32 words
A fiber optic coupler, as defined by any of Claims 1 to 11, characterized in that said reflector (60) is substantially disk-shaped, said disk-shaped reflector having reflective surfaces on both sides thereof.
Claim 14
Dependent Claim
38 words
A fiber optic coupler, as defined by any of Claims 1 to 12, characterized in that said first and second optical fibers (44, 42) have central longitudinal axes (48, 49) disposed at an angle relative to each other.
Claim 15
Dependent Claim
17 words
A fiber optic coupler, as defined by Claim 13, characterized in that said angle is approximately 90°.
Claim 16
Dependent Claim
29 words
A fiber optic coupler, as defined by any of Claims 1 to 14, characterized in that said second multimode optical fiber (42) comprises a step index multimode optical fiber.
Claim 17
Dependent Claim
36 words
A fiber optic coupler, as defined by any of Claims 1 to 15, characterized in that said reflector (60) has a surface which is totally reflective, such that all of the light incident therein is reflected.
Claim 18
Dependent Claim
63 words
A fiber optic coupler, as defined by any of Claims 1 to 16, characterized in that said multimode fiber (42) includes plural reflectors (60) wherein each of said plural reflectors (60) has a diameter (d) which is approximately equal to: where a is the radius of the core (42a) of the multimode fiber (42) and n is the number of said reflectors (60).
Claim 19
Independent Claim
69 words
A method of manufacturing a fiber optic coupler characterized by: cleaving a multimode optical fiber (42) at an angle relative to its longitudinal axis to provide a pair of end faces (120, 122); depositing a reflective surface (60) on one of said end faces, said reflective surface (60) being small compared to the core diameter (42a) of said multi-mode fiber (42); and placing said end faces (120, 122) together.
Claim 20
Independent Claim
69 words
A method of manufacturing a fiber optic coupler characterized by: cleaving a multimode optical fiber (42) at an angle relative to its longitudinal axis to provide a pair of end faces (120, 122); depositing a reflective surface (60) on one of said end faces, said reflective surface (60) being small compared to the core diameter (42a) of said multi-mode fiber (42); and placing said end faces (120, 122) together.
Claim 21
Dependent Claim
36 words
A method of manufacturing a fiber optic directional coupler, as defined by Claim 18, additionally characterized by the step of mounting said multimode fiber (42) in a support structure (50) prior to performing said cleaving step.
Claim 22
Independent Claim
24 words
A method of manufacturing a fiber optic directional coupler, as defined by Claims 18 or 19, characterized in that said angle is approximately 45°.
References Cited (Backward Citations)
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