JPS6114607A - Optical fiber coupler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the field of fiber optics, and more particularly to the field of fiber optics, and more particularly to the field of optical fiber optics, which allows light to be transmitted from one or more fibers to as many as 77 optical fibers. Concerning binding.

The fiber consists essentially of a transparent core surrounded by a material having a lower refractive index than the core;
Total internal internal reflection causes light to propagate coherently along the fiber. There is usually one or many thermal sheaths in each fiber bundle. In various optical fiber transmission applications, a predetermined portion of the light traveling along one fiber (the "main fiber") is transferred to one or more other fibers (the "main fiber").
It is desirable to transmit the light into the main fiber ("tap fiber") or similarly to send the light from the tap fiber ζ into the main fiber. Although the invasive bonding devices of Oshiwa 1 are known, these are difficult to implement, such as removing and fusing individual cores together in a carefully controlled manner. or is inefficient due to the loss of light due to, for example, breaking the IT fiber and coupling it to a preformed coupling device.

In accordance with the present invention, in an apparatus for optically coupling at least one tap fiber having a light-accepting portion to a main fiber, an intermediate portion of the main fiber is held; ? The intermediate portion follows a predetermined path to achieve such a path that the radius of curvature of the bend is small enough that some of the light flowing through the main fiber leaks through the coating at the outer edge of the bend. and means for holding the tapped fiber in a position such that said light-receiving portion receives at least a portion of the light escaping from the sheathing of the outer edge of the bend. An optical fiber coupling device is provided.

We have found that by clamping or otherwise fixing the fibers in precisely predetermined positions, the leakage of the light beams (which is accompanied by transmission) can be reduced. By bending the feed fiber far enough to obtain (determined by measuring the amount of light emitted) a highly reproducible proportion of the feed fiber leaks into the tap fiber. Furthermore, our proposed device according to the invention allows such regenerability to be achieved with extremely high efficiency, and since the technique is non-invasive, the main fiber is protected from all the protection it can have. The main fiber remains continuous throughout its passage therethrough, with no preparation required other than removing a small portion of the layer (not the coating). Kotl(
Removal of a small portion of the axis-holding layer) can be accomplished by factory mechanics without fiber optics-skilled professionals and can be accomplished without leaving any damage to the optical fiber.

A simply constructed device according to the invention uses at least one tapped fiber having an end portion such that the light-receiving portion is formed by an exposed end face; 1i to allow the exposed end face of the tapped fiber to receive a portion of the light that escapes from the bend as it passes through the main fiber.
The means for holding the tap fiber is constituted by the means for holding the end portion of the tap fiber so that the notation is close to the outer surface of the bend in the main fiber.

In the proposed three-opening coupling device, the means for retaining the main fiber is from the first assembly having a mating surface p1.
The means for retaining the tapped fiber comprises a second assembly which can be clamped in a predetermined position against a mating surface, the shape of the assembly being such that the main fiber with a sheath is held at the outer surface of the bend. The reed is such that it lies flat against the mating surface, so that removal of any protective layer protruding from the mating surface exposes said coating.

The first assembly can be formed of a single block perforated to accommodate the main fiber, but according to our proposal the first assembly can be split to provide opposing tear surfaces; at least one of which is shaped to receive and hold the main fiber in a predetermined position, for example by having a groove in which the fiber can be placed or a peg in which the fiber can be placed; Assembly is facilitated and the image parts are hinged or otherwise fastened together to provide a tight assembly. For convenience, according to our proposal, the rabbit assembly is provided with a stripping blade, which can be slid along the matching surface in order to strip the protective layer from the bends in the main fiber, so that the operator can: In a 1% preferred device where there is no need to have a separate stripper of one's own, the first assembly is tightened in a predetermined position by its sliding along a mating surface, and the stripper blade is located in front of the tap fiber in the mtl- direction, thereby
When tightening both assemblies together, all stripping of the protective layer protruding from the mating surfaces is automatically achieved.

This Sansekiguchi arrangement is preferably such that when the light traveling in the main fiber approaches the CK along the seventh axis,
Although the end portion of the tap fiber is approximately parallel to the seventh axis (for example, ±20°), the bend in the main fiber is I'i! 11, and is suspended along a first axis displaced from the addition/axis axis in the 11th direction. This displacement is preferably small, ie, a little smaller than the diameter of the feed fiber. Thus, the tap fiber typically receives light from the main fiber only when the light travels along the main fiber along the first axis in the direction of the bend rather than in the other direction. According to our proposal, when the l# line is displaced in this way, the exposed end face preferably extends within 1.75'/S with respect to the principal axis of the tapped fiber at the termination. Forms an acute angle within. These variable/parameters, namely end angle, linear displacement, and transverse angle, are all interrelated in their effect on the efficiency of the brace, and the selection of a particular bolt for each is different from that of the other. Carve to the optimum value for one thing.

Another particularly useful device for coupling tapped fibers with exposed end faces, other than the three-opening coupling device described above, is the directional four-opening coupling device, which
means for holding the two tapped fibers so that the exposed end faces of the two tapped fibers are proximate to the outer surface of the bend in the main fiber but are positioned substantially symmetrically with respect to the bend; , which allows each tap fiber to receive light traveling along the main fiber in a direction opposite to that received by the other fibers. , the light exiting through the two tap fibers is similarly caused to travel along the main fiber in opposite directions, and the light exiting by one enters the main fiber in the same direction as the light received by the other. Thus, such a device would have a detector connected by seven tap fibers and a light source (with its secrecy core) connected to the other tap fiber. The present invention provides an extremely convenient method for non-invasively integrating a ring main fiber or data bus into a transmission link with a transmission station or data bus.

The amount of light that leaks through the main fiber sheath 81 depends on the radius of curvature of the bend. The smaller the L1 curvature semicircle, the more the amount of light that leaks out. Thus, for example, to split light into two equal parts (albeit smaller by the fingertip)
, a bend with a smaller radius of curvature is required when only 1/70 of the supply is required for removal. however,
The actual curvature required will depend on the size and configuration of the fiber, and in any case will be substantially less than the normal minimum radius of 1 for commercially available fibers.
For example, to split light f: into two equal parts,
The radius of curvature is typically on the order of two days, and under such conditions it is desirable to use such devices with optical fibers that do not deteriorate due to stress sidewalls. Therefore, in this device, polymer fibers (e.g., polymethyl methacrylate fibers) may be used rather than glass fibers, although glass fibers are generally seen as more resistant to such bending. desirable.

The angle at which the main fiber is bent is a factor in the overall efficiency, where the larger the angle, the more
The spread of the leaked light is large, and the portion of the light that can be captured by the fiber is reduced. However, if the angular deviation is small, typically less than about 30°, very little light will leak. Thus, although there is no precise limit to the range of angles of light-transmitting bends (given a sufficiently small radius of curvature of the bend), the practical range is about 20 to 90°, and is desirable.
The range is 35 to jθ0.

It should be noted that if several such devices exist and extract light from a number of tap fibers or a common main fiber, they will They can be placed close together so that the songs merge into a single extended song. Under such conditions, light that cannot be captured by a single tap fiber is available for many adjacent tap fibers arranged around the extended bend,
This maintains good efficiency, so that the tuner is
Both C0 and C0 can be extended at large angles.

Efficiency is also improved by deploying an index-matching gel between the tube and the light-accepting portion, and heat treating the feed fiber in the tube to anneal the fiber also improves efficiency. Improve.

The light-accepting section is created by bending the middle section of the tap fiber in essentially the same way as the main fiber.
It is not conventional to use pre-shaped light-receiving parts since they can be formed in situ in a non-invasive manner. In a device for accomplishing this, the bend is a predetermined path to achieve this, and the radius of curvature of the bend is small enough that some of the light flowing through the fiber falls outside the outer edge of the bend. Light leaking from one fiber can be avoided by keeping the middle portion of the one-tap fiber in a path that would leak through the sheathing of the fiber, and by holding the outer edges of the bends in one fiber close together. Means are designed to hold the tap fiber so that it can be captured by the other fiber. In the darning configuration, one fiber is the main phino, r-
(An immobile wire with the other fiber as the tap fiber is not required.

υ Below, special embodiments of the invention will be described with reference to the drawings.

The main body portion l illustrated in figure W1 is made of polymethyl methacrylate (polymethyl methacrylate).
It consists of blocks of λ9
．． Three interconnected grooves of two widths and one depth are drilled. The axis of the first of these grooves is displaced from the axis of the first and second grooves 3 by a very small amount (for example, by 0.2 to 0.3 m for this dimension of the fiber). . The third groove is formed at an angle of 5o00 with respect to the other one, and the obtuse inner edge formed between the first groove and the third groove has a diameter of the co-tub after drilling the groove. By inserting the rod 5e, it is precisely formed to have a radius of curvature of /111+ given by λ. The lid plate (not shown) is a flat plate of monolithic polymethyl methacrylate, the kneading being bolted to the main body part by means of apertures 6, 7, by which the three grooves are closed to form a tube. It will be done.

The optical fibers // and / in Figure 2 are a combination of fluorophores (
1 coated with me of fluoropolymer)
It is a polymethyl methacrylate fiber with a diameter of 11III, which has a protective sheath when folded, and has a total diameter of about λ, 21EIl. In use, the main fiber 11 has a sheathed portion in order to wrap the completed fiber 73 with a coating. This is then fitted into the 7th and 3rd grooves, so that a tight curve is formed in the turn of the rod S, and the exposed part of the sheath is exposed all around the outside of the bend. Form. The tapped fiber/- has an exposed end portion 15 beveled at an angle of 30° and is pushed into the second groove. The beveled end face then lies near the outside of the bend in the main fiber formed by the ridges 73 that are plucked upward in the orientation shown and produced. All spaces within the groove junctions are then filled with index (1ndex) matching gel. This is accomplished selectively to improve efficiency. A lid plate is then bolted to the front of the body portion to properly hold the fibers.

Although this embodiment may be described as being performed in a different order, this order need not be adhered to, in which the sensor or other optical device transmits light from the ring main fiber through the tap fiber. is supplied. The device according to the invention can be used to attach a K to the end of a tapped fiber ready to be clamped onto a ring main optical fiber at the point of use.
It can be commercially available as a killed product. This is because the main fiber does not have to be degraded by breaking etc. and the point of use can be easily moved along the feed fiber if necessary without any loss of efficiency. Other coupling devices for use surfaces also have substantial practical advantages.

Although this embodiment has been described as extracting light from the ring main fiber, it can also be used as a feed coupling device to feed light into the ring main fiber via a tap fiber. The following two examples show how this type of embodiment can be used in practice and show the results obtained with λ such devices.

EXAMPLE l A coupling device for depositing half of the light in the main fiber was constructed as described with respect to the specific embodiment above. Here, the main fiber is about −
It is bent by 50 degrees by rotating a rod of diameter D to give a radius of curvature of 1.2 m (D), and the refractive index is /,
4 (6 gels were used.

/mW of visible light into the feed fiber at the point extending from the W/groove, approximately 1 IooμW of light exited the output fiber, which was spun from the other end of the main fiber. This is 1. j; gave a small excess loss by dB.

Example: The main fiber is II by turning the curvature-determining stem with an inner diameter of 10 m.
A different device was assembled that was substantially the same as that used in the previous example, except that it was bent by 0. The dough was given a radius of curvature of about 60% at the center of the core. This large radius of curvature reduces light leakage, and the ratio of light exiting the tap fiber to light traveling step by step along the main fiber is only about 1:IO, and the light exiting the main fiber is It is about 750μW, and the light emitted from the extraction fiber is about ? 51 iW''t'.Thus, the excess loss was less than →-Thi÷//dB.

Iil:r Figures 3 and 7 show an injection molded three-opening coupling device, in which the first glue body, 2/ for holding the main fibers, 2, 2f, and the tapped fibers (
As shown in the figure, 11.2 3D solid for holding the ``Tanimono'', 2
It consists of 3. ■Il #l standing 0. Make one longitudinal cut, remove the lip from the 1st λfc, and remove the 1st part.
1V9 is a groove for receiving the rib (Ln1) corresponding to flK.
1), one of which is self-7.
The first assembly can be held against the mating surface of the adhesive body while sliding along the other. One end has an integrated elastic latch,
An end stop 25 with 26 is provided such that when the first assembly is slid along the T i assembly until it abuts the end stop 25, the latch of the T'iM4 solid Second
The hook of the assembly engages with the stopper recess, thereby tightening both assemblies together.

The seventh assembly is longitudinally divided by integral hinges along the edges. One part has optical fiber! -,2,
There is a groove for housing two parts, and the other part is bagged to the fibers to hold them in place one by one. The groove has a straight portions that meet at an angle formed by a matching surface. The fiber is only illustrated in Figure 9, which shows how the fiber (completed with a retaining sheath) is retained by the groove in the F) J/ bend. No. 1 Washi's Hou@Gi Saya 3 pieces stand out from the conformity surface. The snap-coat assembly is also formed with an integral stripping blade 33 (shown alone in the Toda diagram);
The stiffener slides along the mating surface during assembly of the coupling device, stripping the fibers from the fibers of the bend and exposing the back.

In front of the blade there is a recess 3 to accommodate the stripped sheath material.

The second assembly has a passage 83K drilled in the second glue body at an angular change parallel to one arm of the groove in the first assembly, both of which are illustrated in FIG. 1, which is very close to the coaxial line, as in the prototype shown in Figure 7.
The passageway is bored to receive a plug 36 (which is a plastic product of approximately 30 mm) in diameter, which is unsheathed at the end portion to fit into it. to accommodate a tapped fiber (not shown).
It is perforated. The hook that extends on both sides of the plug is the stop plate 3.
When the plug is inserted into the assembly, it will be located at either llI' of the body, so that the bladder will be placed in that position and restrained from rotating. available. The narrow end of the plug has a beveled surface 3g against which the tap fiber can be formed to lie flat. When the plug is placed in the assembly,
Knead its end face and therefore tap the end of the fiber as well.
The main fiber 〇 is held against the exposed body.

Figure S shows the main fiber! / , 5.2 and a single tap fiber 53 are illustrated. These are retained as described above in connection with the 7-position node diagram, but FIG. ////
Divider or Wρ splitter≠! provided. Here, the numbers represent the relative proportions of the light output ignoring all original losses, the hatched area represents the index-fitting gel, and the flammable parameters are as follows:

θb Two curved angle tiles Ro = radius of curvature θ. : End face angle θt : A three-opening coupling device that requires an angle of 1-
can be used and f( can be expressed as shown in Figures 151 and 5b. When the above variable parameters are chosen to give an !io/sθ split, a typical Yuga is the next destination.

As a divider: A vs. B: 3g% Total: 6 chi Excess loss is typically /,,2dB.

As a silk mixer, take an input of 1 ooqb at B and at C.

As shown in the wSb diagram, when used as an io%N output, the typical result is A vs. B = 73% A vs. C: Cutting metal side gOchi excess loss is typically /, 0dB6th The figure shows one main fiber 6/, 6.2 and two take-off fibers 63.6Q L1 which are held in a directional four-opening coupling device.

For this coupling device, no equivalent is known among the common coupling devices for glass fibers.

This coupling device is shown diagrammatically in diagram fA 6a, and a typical result is as follows.

100-human power in A: ioochi in D Human crab A vs. B: 6
Flathead D vs h: <0.3% <interference) A%, 10:
/6S Dv8B: 10% A vs. D: < 3%
D vs. 0: (/chia gs io chi excess loss -), /dB Total loss -io, odB Such a directional coupling device is used to input light into the optical ring main fiber and to increase light from it. It is particularly suitable for use with transmission ring main fibers (local area networks). A g
Such a coupling device in gMt is advantageously used.

FIG. 7 shows one main fiber, two tap fibers formed from the same fiber as the wolfberry, which are held in the shape of a transmitting star coupler. This shape is symmetrical, and there is no essential difference between the main fiber and the fiber forming the take-out section. This coupling device is shown diagrammatically in FIG. 7a. This coupling device is non-invasive and allows one fiber to be removed from the coupling device without any optical degradation, except that the only loss is a short loss of protection. , has essentially the same shape and the same effect as the well-known star-shaped coupling device designed to join the ends of two glass fibers. The result is as follows.

A to C: 5 to A to D: <0.7% (interference) 7.2% Excess loss -/, 4'dB Figure S shows one main fiber g1. g2 and one tapped fiber g3. Showing multiple extraction with gtt #1 [
, both tap fibers are positioned and arranged so that they both receive light approaching the bend from the same direction along the b-section gi of the main fiber and not along the partial width. This is also shown diagrammatically in FIG. 138 and can be used as a divider, eg as a device for decomposing multiples into singles, or as a combiner, eg as a device for multiplexing. A typical result is the following power:

Here, each input is assumed to be 100%.

Divider (device that decomposes multiplex into singlex) M pair B = 11. θ% A vs. C: SO% A/D knee〇% 80% Excess loss -/, OdB Combiner (multiplexing device) B vs. Munida Ochi Cφ) vs. A: Ko Ochi B vs. c: <o
, 3s% c (D) vs. B: <l near, /chi (interference)
(Interference) BoD: <, o, 3s % 0(D) vs. D(c):
<θ,z%DA0chi -Ochi total loss-'1. Od, B Total Loss -7, O dB In the figure, many of the coupling devices 9/ of the type shown in FIG. 6 approach the ring main fiber 9.2 non-invasively. In each case, the ring main fiber is inserted into the coupling device with its af intact, corresponding to 6 and 62 in FIG. One tap fiber corresponding to 63 and 61I is coupled to a light source (with means for modulating the light according to the data to be conveyed) and a detector, respectively. In each case, the coupling device is configured such that the light emitted by the various light sources travels counterclockwise (as seen in the diagonal diagram) along a single ring main fiber, and this also causes the detection oriented in such a way that it can be picked up for transmission to the device.

Figure 1θ shows that the present invention has dual fibers 10/, 10
．． 1 shows diagrammatically how it can be used to supply and access a bidirectional transmission link of the form 1, which requires two devices 103, IO'l according to the invention,
One approaches the upper fiber ioi, and the other approaches the lower fiber lζ-io. Each of these devices also operates exactly as described for the device approaching the ring main fiber and has its own light source S and detector. However, the two detectors and the two light sources each use a common electrical input ios and a common electrical output lθ6, and most conveniently, as shown by the formed into a single unit.

Both Figure 1 and Figure 10 have significant advantages over already known invasive coupling devices. In known coupling devices, where the main fiber is cut, terminated, and inserted into the coupling device at the end, any malfunction that occurs in the coupling device may cause the ring main fiber dimension or the data bus to be completely removed. may generally lead to a total shutdown of the entire system. The device of the invention is non-invasive and allows the entire fiber to continue through the coupling device, even if the coupling device becomes loose or otherwise deteriorates.
The remaining parts continue to operate within them. Similarly,
Additional stations can be coupled to the main fiber at L7 without interrupting work to stations already in operation.

[Brief explanation of the drawing]

In Figure 7, the cover sheet metal has been removed to show the details of ①1.
FIG. 1 is an elevational view of the main body portion of the l embodiment. The νλ diagram shows the main fiber and the tap fiber in a position corresponding to the position they would be held in use, but slightly separated for clarity and in a resting position. FIG. 13 is a longitudinal cross-sectional view of the assembled coupling device shown with the tap plug calibrated for insertion. FIG. 14 shows a portion of the coupling device of FIG. 3 for holding the main fiber; FIG. 5, question! Figures A, 7 and 3 illustrate respective willow deployments of fibers that can be held in suitable three- and four-hole coupling devices according to the present invention. Figure 51, Figure 5b, Figure 6a, Figure 1 and ga
The Figures are diagrammatic representations that give an idea of how the coupling devices forming the shapes of Figures S to 8 are used in practice. Figure 9 shows how many of the coupling devices of Figure 6 can be used for unidirectional transmission ring main fibers; Indicates whether it can be used for In the drawings, l is the main body part, C, 3 and Da are grooves, S
is the rod that gives the bend, 7 is the main fiber, /- is the tapped fiber, 13 is the Shimada covered 1, /4 is the bent, lS is the exposed end portion 1.2/ is the 7th Assembly 1.2
λ is the main fiber 1. 23 is the #co assembly, -da is the matching surface, 32 is the sleeping sheath, and 33 is the stripping blade.

Claims (1)

[Claims] 1. An apparatus for optically coupling at least one tap fiber having a light-receiving portion to a main fiber, comprising a predetermined device for holding an intermediate portion of the main fiber and achieving a bend. means for causing said intermediate portion to follow a path such that the radius of curvature of the bend is sufficiently small that some of all the light flowing in the main fiber escapes from the coating at the outer edge of the bend; and means for holding the tapped fiber in a position such that the portion receiving the fiber receives at least a portion of the light escaping from the coating around the outer edge of the bend. 2. The tapped fiber is positioned so that the exposed end face of the tapped fiber is close to the outer surface of the bend in the main fiber, so that the exposed end face of the tapped fiber receives a portion of the light that escapes from the bend as the light passes through the main fiber. at least one tap fiber having an end portion such that the light-receiving portion is formed by the exposed end face, the means for holding the tapped fiber comprising: The optical fiber coupling device according to claim 1, for coupling fibers. 3. The means for holding the main fiber comprises a first assembly having a mating surface, and the means for holding the tap fiber comprises a second assembly which can be tightened at a predetermined position relative to the mating surface. The shape of the first assembly is
such that the main fiber with the coating lies flat against the mating surface at the outer surface of the bend, so that removal of any protective layer protruding from the mating surface exposes said coating; An optical fiber coupling device according to claim 2. 4. The first assembly is splittable to provide opposing tear surfaces, at least one of which is configured to receive and hold the primary fiber in a predetermined position, and both portions are configured to: 4. A fiber optic coupling device as claimed in claim 3, which is hinged or otherwise fastened to provide a rigid assembly. 5. Optical fiber coupling device according to claim 4, wherein the second assembly comprises a stripping blade, which is slidable along the mating surface to strip the protective layer from the bend in the main fiber. 6. The second assembly is tightened in a predetermined position by its sliding along the mating surface, the stripping blade being located in front of the tap fiber in the direction of the sliding, thereby , when tightening both assemblies together, stripping off of any protective layer protruding from the mating surfaces is automatically achieved;
An optical fiber coupling device according to claim 5. 7. means for holding the two tapped fibers so that the exposed end faces of the two tapped fibers are located close to the outer surface of the bend in the main fiber, but substantially symmetrically with respect to said bend; Claims in the form of a four-aperture coupling device having a four-aperture coupling device, whereby each tapped fiber can receive light traveling along the main fiber in the opposite direction to the light received by the other fibers. The optical fiber coupling device according to item 2. 8. having means for holding a number of tap fibers such that their exposed end faces are located near the outer surface of the bend, all of the tap fibers being received by other tap fibers; Optical fiber coupling device according to claim 2, in the form of a four-aperture coupling device, arranged and arranged so as to receive from the main fiber only light approaching the bend from the same direction as the light. 9. An optical fiber coupling device according to any one of claims 2 to 8, wherein the exposed end face is at an angle of 15-35° with respect to the principal axis of the tapped fiber at the termination. 10. A predetermined path for achieving a bend such that the radius of curvature of the bend is small enough that some of the light flowing through the fiber leaks through the coating around the outer edge of the bend; By holding the middle portions of the tap fibers compliant and the outer edges of the bends in the two fibers close together, light leaking from one fiber can be captured by the other fiber. 2. Optical fiber coupling device according to claim 1, wherein the means for holding the tapped fiber are designed so as to make the tap fiber.