EP0404587A2
Expired / Lapsed
EP
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Optical fiber coupler and a fabrication method for the same
Assignee: Fujikura Ltd
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Filing: 1990-06-22
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Granted: —
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Expires: 2010-06-22
Abstract
Abstract The present invention provides a wide wavelength range optical fiber coupler that to the greatest extent possible, allows optical coupling which is wavelength independent, and thus demonstrates a constant coupling ratio over a wide range of wavelengths. By causing various irregularities (17) to be formed in the fused-elongated region of an optical fiber coupler (16), thereby leading to the generation of additional modes in addition to the fundamental modes, while at the same time causing multiple mode coupling in which the above mentioned additional modes participate in the coupling of the fundamental modes, it is possible to selectively control the coupling strength at determined wavelengths and thereby achieve optical coupling which is largely wavelength independent and thus demonstrates a relatively constant coupling ratio over a wide range of wavelengths. Furthermore, by causing the strength of coupling between the cores of each component optical fiber to vary along the length of the longitudinal axis of each component optical fiber, it is possible to decrease the degree of sinusoidal variation in the wavelength dependance characteristics of each component optical fiber, thereby making it possible to further achieve optical coupling which is wavelength independent and thus considerably constant over a wide range of wavelengths.
Inventors
- 👤 Ryozo Yamauchi
- 👤 Noboru Kawakami
- 👤 Fumio Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 01:19
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29331; G02B6/29332; G02B6/255; G02B6/2552; G02B6/2804; G02B6/2821; G02B6/2835; G02B2006/2865
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
121 words
An optical fiber coupler (11, 16, 20, 31, 36 and 44) formed by fusing a section of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45), and then elongating the fused section to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said optical fiber coupler (11, 16, 20, 31, 36 and 44) characterized in that one or more permutations are introduced into said fused-elongated region (13, 17, 21, 35, 39 and 46) so that a mode coupling state between said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46) is a multiple mode coupling state.
Claim 2
Dependent Claim
121 words
An optical fiber coupler (11, 16, 20, 31, 36 and 44) formed by fusing a section of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45), and then elongating the fused section to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said optical fiber coupler (11, 16, 20, 31, 36 and 44) characterized in that one or more permutations are introduced into said fused-elongated region (13, 17, 21, 35, 39 and 46) so that a mode coupling state between said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46) is a multiple mode coupling state.
Claim 3
Dependent Claim
27 words
An optical fiber coupler (11) in accordance with Claim 1 above further characterized in that said permutation is a twist deformation introduced into said fused-elongated region (13).
Claim 4
Dependent Claim
41 words
An optical fiber coupler (16) in accordance with Claim 1 above further characterized in that said permutation is a wave shaped deformation introduced into one or more of said at least two component optical fibers (12) in said fused-elongated region (17).
Claim 5
Dependent Claim
58 words
An optical fiber coupler (20) in accordance with Claim 1 above further characterized in that said permutation is a glass material (22) which is fused into said fused-elongated region (21), said glass material (22) having an index of refraction no greater than the index of refraction of a cladding of said one or more component optical fibers (12).
Claim 6
Dependent Claim
142 words
A manufacturing method for an optical fiber coupler (11, 16, 20, 31, 36 and 44) in which sections of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said manufacturing method for said optical fiber coupler (11, 16, 20, 31, 36 and 44) characterized in that one or more permutations are introduced into said fused-elongated region (13, 17, 21, 35, 39 and 46) so that a mode coupling state between said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46) is a multiple mode coupling state.
Claim 7
Dependent Claim
142 words
A manufacturing method for an optical fiber coupler (11, 16, 20, 31, 36 and 44) in which sections of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said manufacturing method for said optical fiber coupler (11, 16, 20, 31, 36 and 44) characterized in that one or more permutations are introduced into said fused-elongated region (13, 17, 21, 35, 39 and 46) so that a mode coupling state between said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46) is a multiple mode coupling state.
Claim 8
Dependent Claim
72 words
An optical fiber coupler (31) formed by fusing a section of each of at least two component optical fibers (32, 33 and 34), and then elongating the fused section to form a fused-elongated region (35); said optical fiber coupler (31) characterized in that a strength of mode coupling between cores of said at least two component optical fibers (32, 33 and 34) varies along a longitudinal axis of said fused-elongated region (35).
Claim 9
Dependent Claim
72 words
An optical fiber coupler (31) formed by fusing a section of each of at least two component optical fibers (32, 33 and 34), and then elongating the fused section to form a fused-elongated region (35); said optical fiber coupler (31) characterized in that a strength of mode coupling between cores of said at least two component optical fibers (32, 33 and 34) varies along a longitudinal axis of said fused-elongated region (35).
Claim 10
Dependent Claim
60 words
An optical fiber coupler (36) in accordance with Claim 6 above further characterized in that at least one of said one or more component optical fibers (37 and 38) is a variable external diameter optical fiber (37) of which an external diameter varies along a longitudinal axis of said variable external diameter optical fiber (37) in said fused-elongated region (39).
Claim 11
Dependent Claim
60 words
An optical fiber coupler (44) in accordance with Claim 6 above further characterized in that at least one of said one or more component optical fibers (38 and 45) is a variable propagation constant optical fiber (45) of which a propagation constant varies along a longitudinal axis of said variable propagation constant optical fiber (45) in said fused-elongated region (46).
Claim 12
Dependent Claim
143 words
A manufacturing method for an optical fiber coupler (11, 16, 20, 31, 36 and 44) in which sections of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said manufacturing method for said optical fiber coupler (11, 16, 20, 31, 36 and 44)characterized in that at least one of said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) is such that one or more parameters of said optical fiber varies along a longitudinal axis of said optical fiber (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46).
Claim 13
Dependent Claim
143 words
A manufacturing method for an optical fiber coupler (11, 16, 20, 31, 36 and 44) in which sections of each of at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (13, 17, 21, 35, 39 and 46); said manufacturing method for said optical fiber coupler (11, 16, 20, 31, 36 and 44)characterized in that at least one of said at least two component optical fibers (12, 32, 33, 34, 37, 38 and 45) is such that one or more parameters of said optical fiber varies along a longitudinal axis of said optical fiber (12, 32, 33, 34, 37, 38 and 45) in said fused-elongated region (13, 17, 21, 35, 39 and 46).
Claim 14
Dependent Claim
209 words
A manufacturing method for an optical fiber coupler (36) in which sections of each of at least two component optical fibers (37 and 38) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (39); said manufacturing method for said optical fiber coupler characterized in that at least one of said at least two component optical fibers (37 and 38) is a variable diameter optical fiber (37) of which a diameter varies along a longitudinal axis of said variable diameter optical fiber (37), said variable diameter optical fiber (37) formed by an etching process which is a liquid etching process in which bands of a resist layer (40) are applied around a circumference of an optical fiber (38) at fixed intervals over at least a section of said optical fiber (38), thereby formed circumferential alternating bare optical fiber (38) bands and resist layer (40) covered optical fiber bands over said section of said optical fiber (38), then immersing said section of said optical fiber in an etchant whereby said bare optical fiber (38) bands are etched, then removing said bands of resist layer (40) thereby producing said variable external diameter optical fiber (37).
Claim 15
Dependent Claim
209 words
A manufacturing method for an optical fiber coupler (36) in which sections of each of at least two component optical fibers (37 and 38) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (39); said manufacturing method for said optical fiber coupler characterized in that at least one of said at least two component optical fibers (37 and 38) is a variable diameter optical fiber (37) of which a diameter varies along a longitudinal axis of said variable diameter optical fiber (37), said variable diameter optical fiber (37) formed by an etching process which is a liquid etching process in which bands of a resist layer (40) are applied around a circumference of an optical fiber (38) at fixed intervals over at least a section of said optical fiber (38), thereby formed circumferential alternating bare optical fiber (38) bands and resist layer (40) covered optical fiber bands over said section of said optical fiber (38), then immersing said section of said optical fiber in an etchant whereby said bare optical fiber (38) bands are etched, then removing said bands of resist layer (40) thereby producing said variable external diameter optical fiber (37).
Claim 16
Dependent Claim
88 words
A manufacturing method for an optical fiber coupler (36) in accordance with claim 10 above further characterized in that said etching process is a dry etching process in which a flame containing a gas having glass-corrosive properties is applied at least one location along at least a section of an optical fiber (38), thereby effecting a dry etching of said optical fiber (38) at said at least one location along at least a section of said optical fiber (38), thereby producing said variable external diameter optical fiber (37).
Claim 17
Dependent Claim
167 words
A manufacturing method for an optical fiber coupler (44) in which sections of each of at least two component optical fibers (38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (46); said manufacturing method for said optical fiber coupler (44) characterized in that at least one of said at least two component optical fibers (38 and 45) is a variable propagation constant optical fiber (45) of which a propagation constant varies along a longitudinal axis of said variable propagation constant optical fiber (45), said variable propagation constant optical fiber (45) formed by locally applying heat at at least one location along at least a section of an optical fiber (38), then applying tension parallel to a longitudinal axis of said section of said optical fiber (38), thereby creating an decreased diameter portion at said at least one location, thereby forming said variable propagation constant optical fiber (45).
Claim 18
Dependent Claim
167 words
A manufacturing method for an optical fiber coupler (44) in which sections of each of at least two component optical fibers (38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (46); said manufacturing method for said optical fiber coupler (44) characterized in that at least one of said at least two component optical fibers (38 and 45) is a variable propagation constant optical fiber (45) of which a propagation constant varies along a longitudinal axis of said variable propagation constant optical fiber (45), said variable propagation constant optical fiber (45) formed by locally applying heat at at least one location along at least a section of an optical fiber (38), then applying tension parallel to a longitudinal axis of said section of said optical fiber (38), thereby creating an decreased diameter portion at said at least one location, thereby forming said variable propagation constant optical fiber (45).
Claim 19
Dependent Claim
167 words
A manufacturing method for an optical fiber coupler (44) in which sections of each of at least two component optical fibers (38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (46); said manufacturing method for said optical fiber coupler (44) characterized in that at least one of said at least two component optical fibers (38 and 45) is a variable propagation constant optical fiber (45) of which a propagation constant varies along a longitudinal axis of said variable propagation constant optical fiber (45), said variable propagation constant optical fiber (45) formed by locally applying heat at at least one location along at least a section of an optical fiber (38), then applying tension parallel to a longitudinal axis of said section of said optical fiber (38), thereby creating an increased diameter portion at said at least one location, thereby forming said variable propagation constant optical fiber (45).
Claim 20
Dependent Claim
167 words
A manufacturing method for an optical fiber coupler (44) in which sections of each of at least two component optical fibers (38 and 45) are aligned side by side and mutually thermally fused thereby forming a fused section, and then said fused section is elongated to form a fused-elongated region (46); said manufacturing method for said optical fiber coupler (44) characterized in that at least one of said at least two component optical fibers (38 and 45) is a variable propagation constant optical fiber (45) of which a propagation constant varies along a longitudinal axis of said variable propagation constant optical fiber (45), said variable propagation constant optical fiber (45) formed by locally applying heat at at least one location along at least a section of an optical fiber (38), then applying tension parallel to a longitudinal axis of said section of said optical fiber (38), thereby creating an increased diameter portion at said at least one location, thereby forming said variable propagation constant optical fiber (45).
References Cited (Backward Citations)
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