EP0079196A1
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Passive fiber optic multiplexer
Assignee: Leland Stanford Junior University
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Filing: 1982-11-04
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Granted: —
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Expires: 2002-11-04
Abstract
Abstract A passive, frequency selective, fiber optic multiplexer comprises a directional coupler (10) in which a pair of single mode optical fibers (12a, 12b) are accurately positioned to provide evanescent field coupling, typically by polishing a portion of the cladding (17a, 17b) from each of the fibers (12a, 12b) to place the respective cores (15a, 15b) of the fibers (12a, 12b) within the evanescent field of light in the other fiber (12a, 12b). The coupling efficiency of a coupler (10) constructed in this manner is wavelength dependent, and provides over-coupling, that is, the capability of transferring light, virtually entirely, back and forth between the fibers (12a, 12b) within the coupler (10). The wavelength dependent nature of the evanescent field coupling permits multiplexing, specifically between a pair of wavelengths, one of which is coupled in its entirety from a first fiber (12a) to a second fiber (12b), and the other of which is essentially uncoupled. By increasing the number of total transfers of the light signals between the pair of fibers (12a, 12b), the frequency resolution of the multiplexer may be optimized for light signals of virtually any frequency separation.
Inventors
- 👤 Herbert John Shaw
- 👤 Michel J.F. Digonnet
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 04:03
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29331; G02B6/29332; G02B6/2804; G02B6/2821; G02B6/2826; G02B6/283; G02B6/29379; G02B6/2938; G02B6/29395
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
100 words
A fiber optic multiplexer for combining or separating a pair of optical wavelengths, characterized by: a pair of optical fibers (12a, 12b) arranged in close proximity to provide evanescent field coupling therebetween in an interaction length (32) of the fibers (12a, 12b), the evanescent field coupling between the fibers (12a, 12b) occurring within a coupling length (35) within the interaction region (32), the interaction length (32) being an even multiple of the coupling length (35) of the fibers (12a, 12b) at one of the optical wavelengths and an odd multiple of the coupling length (35) at the other optical wavelength.
Claim 2
Dependent Claim
100 words
A fiber optic multiplexer for combining or separating a pair of optical wavelengths, characterized by: a pair of optical fibers (12a, 12b) arranged in close proximity to provide evanescent field coupling therebetween in an interaction length (32) of the fibers (12a, 12b), the evanescent field coupling between the fibers (12a, 12b) occurring within a coupling length (35) within the interaction region (32), the interaction length (32) being an even multiple of the coupling length (35) of the fibers (12a, 12b) at one of the optical wavelengths and an odd multiple of the coupling length (35) at the other optical wavelength.
Claim 3
Dependent Claim
41 words
A fiber optic multiplexer, as defined in Claim 1, wherein said pair of optical fibers (12a, 12b) are arcuately curved, and wherein said effective interaction length (32) is a function of the radius of curvature of said arcuate fibers (12a, 12b).
Claim 4
Dependent Claim
32 words
A fiber optic multiplexer, as defined in Claim 1 or 2, wherein said pair of optical fibers (12a, 12b) are laterally offset from one another to select said pair of optical wavelengths.
Claim 5
Dependent Claim
49 words
A fiber optic multiplexer, as defined in Claim 3, wherein said pair of optical fibers (12a, 12b) are mounted in rigid blocks (16a, 16b),, said multiplexer additionally being characterized by: apparatus (71, 72, 80) for translating said blocks (16a,16b) relative one another to select said pair of optical wavelengths.
Claim 6
Dependent Claim
38 words
A fiber optic multiplexer, as defined in any preceding claim, wherein said pair of optical fibers (12a, 12b) are arcuate having a radius of curvature selected to define a frequency difference between said first and second optical wavelengths.
Claim 7
Dependent Claim
39 words
6 . A fiber optic multiplexer, as defined in Claim 1, wherein said fibers (12a, 12b) are arcuate and wherein said effective interaction length (32) is a function of the square root of the radius of said arcuate fibers.
Claim 8
Independent Claim
277 words
A method- of multiplexing a pair of optical wavelengths characterized by the steps of: providing two blocks (16a, 16b) of rigid material with first and second generally parallel planar faces (18a, 18b); forming a slot (13a, 13b) across a face of each of the blocks (16a, 16b), each said slot (18a, 18b) having a greater depth toward the edges of the block (16a, 16b) than toward the center of the block (16a, 16b); mounting a strand (12a, 12b) of fiber optic material having a core portion 15a, 15b) and a cladding portion (17a, 17b) in each of the slots (13a, 13b).so that the strands (12a, 12b) extend along paths corresonding to the bottom walls of the slot (13a, 13b), respectively; removing material from each of the strands (12, 12b) and the faces (18a, 18b) of the blocks (16a, 16b) in a planar fashion until the cladding portion (17a, 17b) of each strand (12, 12b) is within a few microns of the core portion (17a, 17b) in the center of the slot (13a, 13b) and no material is removed from the strand (12a, 12b) at the edges of the block (16a, 16b); and placing the blocks (16a, 16b) together with the faces (18a, 18b) in facing relationship and the core portions (17a, 17b) of the strands (12a, 12b) in close proximity to each other where the cladding (15a, 15b) has been removed to form a region (32) in which guided modes of the strands (12a, 12b) interact through evanescent field couplings to cause light of selected wavelengths to be transferred between the two strands (1 2 a, 12b) while light of other selected wavelengths is not so transferred.
Claim 9
Independent Claim
277 words
A method- of multiplexing a pair of optical wavelengths characterized by the steps of: providing two blocks (16a, 16b) of rigid material with first and second generally parallel planar faces (18a, 18b); forming a slot (13a, 13b) across a face of each of the blocks (16a, 16b), each said slot (18a, 18b) having a greater depth toward the edges of the block (16a, 16b) than toward the center of the block (16a, 16b); mounting a strand (12a, 12b) of fiber optic material having a core portion 15a, 15b) and a cladding portion (17a, 17b) in each of the slots (13a, 13b).so that the strands (12a, 12b) extend along paths corresonding to the bottom walls of the slot (13a, 13b), respectively; removing material from each of the strands (12, 12b) and the faces (18a, 18b) of the blocks (16a, 16b) in a planar fashion until the cladding portion (17a, 17b) of each strand (12, 12b) is within a few microns of the core portion (17a, 17b) in the center of the slot (13a, 13b) and no material is removed from the strand (12a, 12b) at the edges of the block (16a, 16b); and placing the blocks (16a, 16b) together with the faces (18a, 18b) in facing relationship and the core portions (17a, 17b) of the strands (12a, 12b) in close proximity to each other where the cladding (15a, 15b) has been removed to form a region (32) in which guided modes of the strands (12a, 12b) interact through evanescent field couplings to cause light of selected wavelengths to be transferred between the two strands (1 2 a, 12b) while light of other selected wavelengths is not so transferred.
Claim 10
Dependent Claim
37 words
8 . The method of claim 9 wherein the relative translational and rotational positions of the blocks (16a, 16b) are adjusted to selectively vary the interaction region (32) between the guided modes to select said selected wavelengths.
References Cited (Backward Citations)
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