Optical fiber positioning device and method

Abstract

A device comprising a base and an area for receiving an optical fiber holder fixed to the base. The optical fiber holder includes a clip that is operable between an open position in which the optical fiber is movable relative to the optical fiber holder with respect to longitudinal, rotational, and transverse movement, and a closed position in which the optical fiber is fixed relative to the optical fiber holder. The device also includes a clamp rotatably mounted on the base to allow rotation about an axis coincident with the longitudinal axis of the held optical fiber. The clamp is for clamping the held optical fiber and is operable between an unclamped position and a clamped position in which the optical fiber is fixed relative to the base with respect to longitudinal and transverse movement, but is rotatable about the longitudinal axis of the optical fiber.

Description

Technical Field

[0001] Background

[0001] The present invention relates to a device and method for positioning an optical fiber.

Background Art

[0002]

[0002] The formation of a permanent joint between the ends of two portions of an optical fiber is a common operation in the fields where optical fibers are used. In many cases, the joint is formed by fusion splicing, in which case the fibers are aligned between end faces and heated in the end regions to soften the glass from which the fibers are made. By pressing the ends together, the softened glass is fused, and when the glass cools and hardens, the fibers are permanently connected. The joint is called a splice. The quality of the splice is an important factor in enabling low-loss optical propagation of light moving from one fiber to another. Reducing structural discontinuities in the splice by accurately aligning the structural features in the two fibers contributes to low loss.

[0003]

[0003] Conventional solid-core optical fibers, which include an annular cladding surrounding a circular core, are relatively easy to align for splicing. This structure has continuous rotational symmetry in cross-section, so the core and cladding are necessarily aligned by aligning the fiber ends transversely to match the position of the longitudinal axis of the fiber. However, many optical fibers have more complex internal structures that lack continuous rotational symmetry. Some fibers are completely asymmetric with respect to their transverse structure, so there is only a single rotational position in which two fibers can be aligned. Other fibers have multiple rotational symmetries, so alignment is performed at multiple rotational positions. Examples include some polarization-maintaining fibers that may have double rotational symmetry, and anti-resonant hollow-core fibers having a central hollow core surrounded by an inner cladding formed by a ring of N hollow glass capillaries extending along the fiber length, which gives the fiber N-fold rotational symmetry and corresponding N rotational positions in which the structure of two fibers can be aligned. Careful structural alignment of the inner cladding of two such fibers in a splice is crucial for maintaining the beneficial properties of this type of fiber, including very low optical propagation loss compared to solid-core fibers.

[0004]

[0004] Splicing of optical fibers can be conveniently carried out using a dedicated fusion splicer that accepts the ends of two fibers and performs automated alignment of the ends before heating and melting the glass to form the splice. When designed for use with solid core optical fibers, fusion splicers typically lack any rotational alignment capability.

[0005]

[0005] The embodiments described below are not limited to implementations that solve any or all of the drawbacks of known fiber positioning or fiber splicing devices. [Overview of the Initiative]

[0006] overview

[0006] The following provides a brief overview of the disclosure to the reader in order to provide a basic understanding. This overview is not intended to identify any major or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Its sole purpose is to present in a concise form certain concepts disclosed herein as a prelude to more detailed descriptions to be presented later.

[0007]

[0007] The aspects and embodiments are described in the appended claims.

[0008]

[0008] According to a first aspect of several embodiments described herein, a device for positioning an optical fiber is provided, comprising a support base and a receiving area on the support base configured to receive an optical fiber holder such that the optical fiber holder is fixed to the support base, the optical fiber holder being for holding an optical fiber and including a clip operable between an open position in which the optical fiber held in the optical fiber holder is movable relative to the optical fiber holder and a closed position in which the held optical fiber is fixed to the optical fiber holder with respect to longitudinal, rotational and transverse movement of the optical fiber, the support base comprising a receiving area configured to enable the clip to operate between the open and closed positions when the optical fiber holder is received within the receiving area and a clamp movably mounted on the support base to enable rotation about an axis coinciding with the longitudinal axis of the optical fiber held in the optical fiber holder, the clamp being configured to clamp the optical fiber held in the optical fiber holder when received within the receiving area and including an open position in which the optical fiber is not clamped to the support base and a closed position in which the optical fiber is clamped and fixed to the support base with respect to longitudinal and transverse movement of the optical fiber, but is rotatable about the longitudinal axis of the optical fiber.

[0009]

[0009] A second aspect of some embodiments described herein provides a method for positioning an optical fiber, the method comprising: placing an optical fiber in an optical fiber holder and fixing the optical fiber with respect to the optical fiber holder for movement in the longitudinal, transverse and rotational directions of the optical fiber; arranging the optical fiber holder on a support base such that the optical fiber holder is fixed to the support base; clamping the optical fiber with a clamp that, when closed, fixes the optical fiber with respect to the support base for movement in the longitudinal and transverse directions of the optical fiber, but allows rotation of the optical fiber about its longitudinal axis; releasing the optical fiber from the optical fiber holder for movement relative to the optical fiber holder; rotating the optical fiber about its longitudinal axis to achieve a desired rotational position of the optical fiber; fixing the optical fiber at the desired rotational position relative to the optical fiber holder; and releasing the optical fiber from the clamp.

[0010]

[0010] These and further aspects of specific embodiments are described in the attached independent and dependent claims. It is understood that the features of the dependent claims may be combined with each other and with the features of the independent claims in combinations other than those expressly described in the claims. Furthermore, the methods described herein are not limited to specific embodiments such as those described below, but include and intend to include any suitable combination of the features presented herein. For example, apparatus and methods may be provided according to the methods described herein, which may, as appropriate, include any one or more of the various features described below. Many of the accompanying features will be more readily apparent, as they will be better understood by referring to the following detailed description, which will be considered in relation to the attached drawings.

[0011] Description of the drawing

[0011] This description will be better understood from the following detailed description, which will be read in reference to the attached drawings. [Brief explanation of the drawing]

[0012] [Figure 1] A simplified cross-sectional view of an exemplary anti-resonant hollow core optical fiber to which the methods and apparatus described herein can be applied is shown. [Figure 2] This graph shows the variation in optical propagation loss with respect to the angular position of two butt-coupled anti-resonant hollow core fibers. [Figure 3] A simplified schematic perspective view of an exemplary optical fiber holder suitable for use in the methods and apparatus of this disclosure is shown. [Figure 4] A simplified schematic side cross-sectional view of an optical fiber positioning device according to an aspect of this disclosure is shown. [Figure 5] A simplified schematic end view of an optical fiber clamp that may be included in an optical fiber positioning device according to an aspect of this disclosure is shown. [Figure 6] A flowchart of a first exemplary method according to an aspect of this disclosure is shown. [Figure 7] A simplified representation of a display screen that may be included in an optical fiber positioning device according to an aspect of this disclosure is shown. [Figure 8] A flowchart of a second exemplary method according to an aspect of this disclosure is shown. [Modes for carrying out the invention]

[0013] In the attached drawings, similar reference numerals are used to specify similar parts.

[0014] Detailed explanation

[0012] The detailed description provided below in relation to the attached drawings is intended to describe this example and is not intended to represent the only form in which this example may be constructed or used. This description describes the function of the example and the sequence of operations to construct and operate the example. However, the same or equivalent functions and sequences may be achieved by various examples.

[0015]

[0013] Many optical fibers have an internal structure with discrete features that cause the fiber to lack continuous rotational symmetry. In such cases, butt jointing of two parts of the fiber placed between the ends can result in significant optical propagation loss across the joint if the structures are not perfectly aligned within the two fibers, for example, when forming a splice. Alignment requires careful rotational adjustment around the longitudinal axis of the fiber to align the structural features, and this can be cumbersome and time-consuming to achieve.

[0016]

[0014] Figure 1 shows an exemplary cross-sectional view of an optical fiber in which this problem occurs. The fiber is an anti-resonant hollow core fiber (ARF) in which light is induced by the anti-resonant optical effect. The fiber 10 has an outer tubular cladding or jacket 3. The structured inner cladding 1 includes a plurality of tubular cladding capillaries 14, in this example six capillaries of the same cross-sectional dimensions and shape, arranged inside the outer cladding 3 in a single ring such that the longitudinal axes of each cladding capillary 14 and the outer cladding 3 are substantially parallel. Each cladding capillary 14 is in contact with (e.g., bonded to) the inner surface of the outer cladding 3 at an azimuthal position 16 such that the cladding capillaries 14 are uniformly spaced around the inner circumference of the outer cladding 3 and also spaced apart from each other by gaps 5 (no contact between adjacent capillaries). In some ARF designs, the clad tubes 14 can be positioned in contact with each other (in other words, not spaced apart as shown in Figure 1), but spacing to eliminate this contact can improve the optical performance of the fiber. Spacing 5 eliminates contact points that occur at the contact points between adjacent tubes, which tend to cause undesirable resonances that result in high losses. Thus, a fiber with spaced-out clad capillaries can be called a "contactless anti-resonant hollow core fiber".

[0017]

[0015] The arrangement of the clad capillary 14 within the inner ring surrounding the tubular outer clad 3 results in a central space, cavity, or void within the fiber 10, which is the hollow core 2 of the fiber, and its longitudinal axis is also parallel to the longitudinal axes of the outer clad 3 and the capillary 14. The core 2 is confined by the portion of the outer surface of the clad capillary 14 that faces inward. This is the core boundary, and the material of the capillary wall constituting this boundary (glass or, for example, polymer) provides the necessary anti-resonant photo-induction effect or mechanism. The capillary 14 has a thickness t at the core boundary that defines the wavelength at which anti-resonant photo-induction occurs within the ARF.

[0018]

[0016] In addition, each clad capillary 14 has a secondary, smaller capillary 18 nested inside it, with the capillary 18 bonded to the inner surface of the clad capillary 14 having the same azimuthal angle position 16 as the bonding point between the main capillary 14 and the outer clad 3 in this example. These additional smaller capillaries 18 can reduce optical loss. Additional even smaller tertiary capillaries may be nested inside the secondary capillaries 18. This type of ARF design with secondary and optionally smaller further capillaries may be called a “nested anti-resonant node-free fiber” or NANF. However, the nested capillaries are optional, and some ARF designs do not have nested capillaries.

[0019]

[0017] More generally, many capillary configurations are possible for the structured cladding of the ARF, and therefore Figure 1 is merely an example. The capillaries do not need to have a circular cross-section and / or may or may not all be the same size and / or shape. The number of capillaries surrounding the core may be, for example, 4, 5, 6, 7, 8, 9, or 10, but other numbers are not excluded.

[0020]

[0018] Despite the exact details of the structure, it becomes clear from FIG. 1 that the ARF lacks continuous circular symmetry, and thus care should be taken when joining some parts of such fibers to create a splice. In the example of FIG. 1, since the six nested cladding capillary groups are of equal dimensions and shape, they give a six-fold rotational symmetry such that there are only six rotational positions where two parts of the fiber are precisely structurally aligned. At intermediate positions, the cladding capillaries will be misaligned, giving a structural discontinuity at the joint, whereby the propagating light experiences loss and the overall performance of the spliced fiber is negatively affected.

[0021]

[0019] FIG. 2 shows a graph of optical loss across a butted joint (a joint where the end faces of two optical fibers are joined together) between two parts of a fiber having an ARF fiber, in this example five cladding capillaries, and corresponding five-fold rotational symmetry, in contrast to the six-fold symmetry of the example of FIG. 1. The graph shows the variation of optical loss (in decibels) with azimuthal or rotational angle about one longitudinal axis of a fiber part with respect to the other fiber part. Line “a” shows the exemplary optical loss expected for a perfectly structured optical fiber without defects, showing the loss over a full 360° rotation of one fiber part with respect to the other fiber part. Five troughs of minimum loss can be seen at regular intervals, corresponding to the capillary structure that repeatedly aligns as the fiber is rotated. At intermediate angles, the capillary structure will be more misaligned, giving peak losses that decrease as the structure approaches the next alignment position. Line “b” shows the variation of losses measured from an actual fiber, with periodic loss excursions superimposed on a larger gradual loss curve “c” resulting from eccentricity in the measuring apparatus and fiber structure, causing a further lack of alignment of the capillary structure.

[0022]

[0020] From here, it can be understood that the ability to adjust the rotational direction position of the non-rotationally symmetric optical fiber before bonding and splicing is beneficial for reducing splicing loss. The present disclosure describes an apparatus and method by which such rotational direction positioning can be implemented. The described apparatus and method are applicable to all optical fibers particularly related to the ARF type optical fibers discussed above and other optical fibers specially designed with non-circular symmetric cross-sectional structures. With respect to circularly symmetric optical fibers, this approach may still be useful for enabling inspection and possible orientation in the rotational direction, for example, to address any minor structural asymmetries resulting from manufacturing defects.

[0023]

[0021] FIG. 3 shows a simplified perspective view of a device for holding an optical fiber, hereinafter referred to as an optical fiber holder in this specification. Such an optical fiber holder can be used, for example, to hold an optical fiber in a fixed position and orientation during a process such as cleaving. The optical fiber holder 20, in this example, includes a relatively thin plate 22 having an upper surface 22a, on which the optical fiber 24 is held in a predetermined position or laid flat, and its longitudinal axis is parallel to the upper surface 22a. The plate 22 may include a straight groove (not shown) within its upper surface 22a, and the optical fiber 24 can be placed within this groove to assist in the placement, although this is not essential. The optical fiber 24 is placed on the plate 22, and one of its ends 26 projects a short distance beyond the end of the plate 22, which can be considered as the working end of the optical fiber 24, i.e., the end to be processed. Usually, a part of the outer coating of the optical fiber 24 immediately adjacent to the working end is removed to provide an exposed cladding at the end 28 of the uncoated fiber, which terminates within the end face or end facet 30 of the optical fiber 24. The opposite end 24a of the optical fiber 24 is a free end and can thus extend a considerable length beyond the optical fiber holder 20 depending on the use of the optical fiber 24.

[0024]

[0022] The optical fiber holder 20 includes a clip 32 for securing the optical fiber 24 to the optical fiber holder 20. In this example, the clip 32 is a small, substantially straight element made of metal, for example, attached at one end to the upper surface 22a (fiber holding surface) of the plate 22 by a hinge joint 34 that allows the clip 32 to move between a first position (dotted line) where the clip 32 is away from the upper surface 22a and a second position (solid line) where the clip 32 is in contact with the upper surface 22a. In the first position, the clip 32 is open and the upper surface 22a is exposed so that the optical fiber 24 can be placed on it. Once the optical fiber 24 is positioned, the clip 32 can be moved to a second position where it is closed, so that the clip 32 covers the optical fiber 24 so that the optical fiber 24 is sandwiched between the back surface of the clip 32 and the upper surface 22a of the plate 22, thereby securing the optical fiber 24 to the upper surface 22a (in the groove, if present). The clip 32 is securely closed to grip or press the optical fiber 24. In this way, the optical fiber 24 is fixed to the optical fiber holder 20 so that it cannot move (or move to any detectable extent) in any direction, namely the longitudinal direction (along the length of the optical fiber), the transverse direction (later or perpendicular to the length of the fiber), or the rotational direction (rotation about the longitudinal axis of the optical fiber). The clip 32 may be spring-fastened or engaged by a clasp or magnet, for example, to achieve this secure grip of the optical fiber 24. The described configuration of the clip 32 is merely an example, and any configuration may be used that provides a clip or similar element that is operable (usually manually operable by the user, but automatic placement is not ruled out) between an open position in which the optical fiber in the optical fiber holder 20 can move relative to the holder 20 (e.g., can be placed in the holder, removed from the holder, or repositioned relative to the holder) and a closed position in which the optical fiber in the holder 20 is securely held so that the optical fiber is fixed or substantially fixed relative to the holder 20.

[0025]

[0023] The purpose of such an optical fiber holder is to enable the placement of an optical fiber in a proper position within a fiber processing device, such as a fiber cleaver or fiber fusion splicer, and it is important that the end of the fiber is correctly positioned relative to the device and / or part of another fiber in order to enable the proper execution of the associated process. Accordingly, the optical fiber holder 20 may have one or more locator elements that enable it to be fixed in position relative to other devices and in position within those devices. The locator elements may include one or more through holes 36 that extend all or partially from their back side through the plate 22 for engagement with protruding pins in or on the fiber processing device. In other examples, the locator elements may include one or more magnets in the plate 22 that interact with and attract magnets in the fiber processing device in order to fix the optical fiber holder 20 in the correct position. In other examples, the optical fiber holder 20 may not have any dedicated locator elements, the fiber processing device may have a recess into which the plate 22 fits tightly, or the fiber processing device may include one or more fasteners or latches that engage with the plate 22 to securely hold the plate 22. Other alternative configurations are readily apparent.

[0026]

[0024] One example of the use of such optical fiber holders is in the cleaving and subsequent splicing of optical fibers. For cleaving, an optical fiber, stripped of its coating at a working end, may be fixed in an optical fiber holder and thus placed in a fiber cleaver that operates to cleave the working end of the fiber to provide a suitable end face for splicing. At this time, the end face has a fixed position relative to the optical fiber holder for fixing the fiber in the holder. Next, the optical fiber holder holding the cleaved fiber may be removed from the fiber cleaver and placed directly in a suitable splicer (which fits both the fiber cleaver and the optical fiber holder), thereby the optical fiber holder necessarily positions the end face in the correct position for the operation of the splicer. This process may be repeated with a second optical fiber, and the splicer is configured to receive a second optical fiber holder holding the cleaved optical fiber such that the two end faces are in substantially the correct position for the operation of the splicer.

[0027]

[0025] Typically, a splicer or splicing device may include automated alignment of two end faces relative to each other. This may involve observation or detection of the end faces by a camera, depending on the observation position, and the operation of alignment software that controls small movements of an optical fiber holder to correctly position the fiber for splicing. However, such movements are usually only permitted in the longitudinal and transverse directions and do not involve any rotation of the fiber. In rare cases, a splicing device may additionally provide rotational movement, but such devices are slow, expensive, delicate, bulky, and therefore very suitable only for indoor laboratories and cleanrooms rather than for field use. However, in many cases, fiber splicing needs to be done in the field, such as during the installation of an optical fiber communication network. This type of application preferably requires equipment that is robust, portable, simple, and fast-acting (for example, because there may be more than 100 optical fibers in any given cable). While simple fusion splicers that meet these criteria are available, they lack the ability to align the fiber in the rotational direction, making them unsuitable for achieving low-loss splices with fiber types such as anti-resonant hollow-core optical fibers. Furthermore, devices that provide rotational movement typically involve the rotation of the optical fiber holder rather than the optical fiber itself.

[0028]

[0026] Accordingly, it is proposed herein to introduce an optical fiber positioning device configured to enable rotational positioning of an optical fiber before the optical fiber is placed in a splicing device (or other fiber processing device) and, if necessary, after the fiber is cleaved in a cleaving device. The device maintains the longitudinal and transverse positions of the fiber relative to the optical fiber holder, while enabling rotational positioning of the optical fiber relative to the optical fiber holder. This means that when an optical fiber held in an optical fiber holder is cleaved, the optical fiber is rotationally oriented with respect to the optical fiber holder before it is placed in the fiber splicer with the optical fiber holder, by the position of the end face established by the cleaving, which is maintained so that the optical fiber is correctly placed in the splicer and further correctly oriented in the rotational dimension for rotational alignment with another optical fiber to be spliced. By enabling rotational orientation to be performed with respect to the optical fiber holder, rotational orientation of a second fiber can be performed in parallel with the splicing of the first fiber, both before and separately from the splicing operation. This increases the overall speed of the complex work required to repair cable damage, for example, when a cable may contain a large number of fibers as mentioned above.

[0029]

[0027] Figure 4 shows a simplified schematic side section view of an exemplary optical fiber positioning device according to one embodiment of the present disclosure. The device 40 allows rotation of the optical fiber about its longitudinal axis and subsequent fixing of the optical fiber in a desired rotational direction, while the longitudinal and translational positions of the optical fiber are maintained during rotation and fixed along the desired rotational direction. This is achieved by receiving the optical fiber having a fixed position relative to the optical fiber holder so that the optical fiber holder is fixed to the device, additionally fixing the optical fiber position relative to the device only in the transverse and longitudinal directions, releasing the optical fiber from the optical fiber holder so that the fiber can move relative to the optical fiber holder and device only in the rotational direction, adjusting the rotational position, re-fixing the optical fiber to the optical fiber holder in the desired rotational direction so that the optical fiber has a new rotational direction as well as the previous transverse and longitudinal positions relative to the optical fiber holder, and releasing the optical fiber from the device.

[0030]

[0028] The device 40 includes a support base 42 to which an optical fiber held in the optical fiber holder can be mounted for rotational alignment of the optical fiber. The support base 42 has a receiving area 44 for receiving an optical fiber holder 20, such as the holder described with reference to Figure 3. The receiving area 44 secures the optical fiber holder 20 to the support base 42 by any of the methods described with reference to the example in Figure 3, for example, by magnets, cooperative pins and through holes, latches or recesses of corresponding size (as depicted). When the optical fiber holder 20 is in the receiving area 44, the optical fiber 24 held in the optical fiber holder 20 and secured in the optical fiber holder 20 by the clip 32 is also secured to the support base 42. The receiving area 44 is configured so that the clip 32 of the optical fiber holder 20 can move between its closed position and its open position (as depicted) while the optical fiber holder 20 is in the receiving area. In some examples, this is achieved by an optical fiber holder 20 that is received within a receiving area 44 having its fiber-holding surface, and so its clip 32 is exposed and facing outward (upward as depicted) so that a user can access the clip 32 to move it when the optical fiber holder 20 is within the receiving area 44. However, other arrangements such as a clip operating mechanism for engaging with, releasing, and closing the covered optical fiber holder and clip are not ruled out.

[0031]

[0029] The optical fiber 24 held within the optical fiber holder 20, which is received within the receiving area, has its longitudinal axis L aligned along the direction Z (which is substantially parallel to the support base 42). When the clip 32 is closed, the fixing of the optical fiber holder 20 and thus the optical fiber 24 fixes the optical fiber 24 in place relative to the support base 42, preventing longitudinal movement along the Z direction, transverse movement in the XY plane perpendicular to the Z direction and the longitudinal axis L of the optical fiber 24, and rotational movement R about the longitudinal axis L of the optical fiber 24.

[0032]

[0030] The device 40 also includes a clamp 46 mounted on a support base at a position spaced apart from the receiving area 44 along the Z direction. In the closed position, the clamp 46 holds and grips the optical fiber, and in this example, its position allows the clamp 46 to grip the optical fiber 24 held within the optical fiber holder 20 at a position along the free end 24a of the optical fiber 24 where the optical fiber 24 extends beyond the optical fiber holder 20. The clamp 46, shown schematicly only in Figure 4, is rotatably mounted on the support base 42 such that the clamp 46 rotates relative to the support base 42 and the optical fiber 24 held within the clamp 46 rotates with the clamp 46. The mounting of the clamp 46 on the support base 42 is arranged such that the movement of the held optical fiber 20 is rotational movement about the Z direction (in other words, rotation R of the optical fiber 24 about its longitudinal axis L).

[0033]

[0031] Figure 5 shows a simplified schematic end view of an example of the clamp 46 (and therefore along the Z direction shown in Figure 4). The clamp 46 is rotatably mounted on a support base of a device (not shown here) and in this example includes a lower portion 60 having a surface for receiving an optical fiber 24 through an optional groove 62 in the surface of the lower portion 60, and an upper portion 64 facing the surface of the lower portion 60, which is hinged to the lower portion 60 by a hinge 66, a swivel joint or similar arrangement. The upper portion 64 is movable via the hinge 66 between an accessible open position (dashed line) for the surface of the lower portion 60 to receive the optical fiber 24 and a closed position (solid line) in which the upper portion 64 engages with the optical fiber 24 to prevent the movement of the optical fiber 24 within the clamp 46 and holds or clamps the optical fiber 24 against the surface of the lower portion 60. When the clamp 46 is closed, the optical fiber 24 is fixed to the clamp 46 with respect to longitudinal, transverse and rotational movement. However, the mounting of the clamp 46 on the device's support base means that the clamped optical fiber 24 is fixed to the support base with respect to its longitudinal and transverse movements, but that rotational movement R of the optical fiber 24 about its longitudinal axis L relative to the support base occurs together with the rotation of the clamp 46 about its rotational mounting on the support base. It should be noted that this example of the clamp 46 is illustrative and therefore not limiting; that is, any releaseable method for securely gripping the optical fiber may be used.

[0034]

[0032] In Figure 4, the clamp 46 is positioned to clamp the fiber 24 at its free end 24a, i.e., the portion of the fiber 24 that extends beyond the optical fiber holder 20 on the opposite side of the working end 28 of the fiber 24. This is a practical arrangement, especially when the working end 28 is already cleved so that the end face 30 of the fiber 24 becomes a cleved termination face ready for splicing, since the working end 28 of the fiber does not usually need to extend far beyond the optical fiber holder 20. Thus, there is little space available to clamp the fiber 24 at the working end 28. However, this arrangement is not restrictive, and therefore the clamp 46 could instead clamp the fiber 24 at its working end 28, or two clamps 46 could be provided to clamp the fiber 24 at both its free end 24a and its working end 28. If two clamps are provided, a first clamp 46 at the free end 24a and a second clamp 58 at the working end 28, the second clamp may differ from the first clamp 46. In various examples, the second clamp positioned at the working end 28 of the fiber 24 is not rotatably mounted. The second clamp provides an aperture that, when in the open position, does not restrict the position of the fiber 24, and when in the closed position, allows rotational movement of the fiber 24 within the aperture, except for transverse movement in the XY plane.

[0035]

[0033] Figure 6 shows a flowchart of the steps in an exemplary method for positioning an optical fiber according to one embodiment, for example, by using the optical fiber holder in the example of Figure 3 and the device in the example of Figure 4. In the first step S1, an optical fiber having a working end and a free end is placed in the optical fiber holder and fixed to the optical fiber holder such that longitudinal, transverse, and rotational movement of the fiber is prevented by restricting the fiber with the clips of the optical fiber holder, for example as in Figure 3. In the second step S2, the optical fiber holder is placed in the optical fiber positioning device by placing the optical fiber holder in the receiving area of ​​the support base of the device in Figure 4, for example. In this way, the optical fiber holder and thus the fiber held therein are fixed to the device. In the third step S3, the optical fiber is clamped to the device using a clamp (such as the clamps in Figures 4 and 5) that is rotatably mounted on the device so that the fiber is further fixed to the device and thus to the optical fiber holder with respect to longitudinal and transverse movement via the clamp. In the fourth step S4, the optical fiber is released from the optical fiber holder, for example, by opening the clip of the holder shown in Figure 3. Here, the fiber has a fixed position relative to the optical fiber holder and the device in the longitudinal and transverse directions because it is clamped within the clamp, but it can move rotatably relative to the device and the optical fiber holder because the clamp can rotate freely relative to the device. This configuration is shown in Figure 4, where the clip of the optical fiber holder is open, but the fiber is held in the clamp. In the fifth step S5, the optical fiber is rotated about its longitudinal axis relative to the optical fiber holder and therefore also relative to the device in order to position the fiber in a desired rotational direction. During rotation, the longitudinal and transverse positions of the fiber are maintained so that the fiber is held in the clamp. Conveniently, this rotation can be performed, for example, by rotating the clamp, which may be accessible for manual operation by the user, or it can be driven by a motor that can be controlled by the user or software.Alternatively, the fiber supporting the clamp can be rotated directly, for example, by a user holding the fiber and twisting it. Once the desired rotational position is achieved, the method proceeds to the sixth step S6, in which the optical fiber is again fixed in all directions of movement relative to the optical fiber holder and device by, for example, closing the clip of the optical fiber holder in Figure 3. This fixes the fiber in the required rotational direction while maintaining the existing longitudinal and transverse positions. In the seventh step S7, the fiber is released from the clamp so that it is no longer directly fixed or secured to the device. In the eighth step S8, the optical fiber holder, which has the optical fiber held, correctly oriented and positioned within it, can be removed from the device as needed, for example, to place the fiber held by the optical fiber holder into a fiber processing device such as a fiber splicer.

[0036]

[0034] To enable the alignment of the optical fiber in a desired rotational direction, it is practical to use or provide some observation devices that allow viewing of the cross-section of the fiber. In this way, a direct visual inspection of the internal structure of the optical fiber can be performed so that its rotational direction can be confirmed. This visual inspection may be performed by the user and the rotational position of the fiber may be manually adjusted accordingly, or the view of the fiber may be processed by a computer processor configured to generate control signals to result in adjustment of the rotational direction and transmit them to an automatically rotatable clamp. The observation device is separate from the optical fiber positioning device and may be used in conjunction with it, for example, a fiber inspection or observation device may be available for general fiber observation applications. In this case, the device may include a camera that observes the end of the optical fiber and transmits the captured image of the fiber end to a display screen that the user can view or to a processor for automatic control. Non-camera-based methods may be used, such as a microscope or a similar arrangement of observation and magnifying lenses and mirrors. In some examples, the observation device is incorporated into the optical fiber positioning device, which is advantageous because it is user-friendly. This can be done without a significant increase in the size of the device, so that the device can remain compact and practical for, for example, field use.

[0037]

[0035] Returning to the example in Figure 4, an exemplary observation apparatus is shown. Observing the end of a fiber means that the rotational position of the optical fiber along its longitudinal axis can be evaluated. This can be most easily done by observing a cross-section of the fiber end, in other words, by observing an "end-face" view of the fiber end, by looking along its longitudinal axis. Observing a side view of the fiber end is also possible, but requires more interpretation of the view to determine the orientation of the fiber. Thus, end-face observation is easier for the user to handle. To perform end-face observation, the device in Figure 4 includes an observation apparatus 48 that includes a camera 50 that images the working end 28 of the optical fiber 24 in the end-face view, so the optical axis of the camera 50 is oriented along the longitudinal axis of the fiber 24, i.e., the Z direction, or at least parallel to the longitudinal axis of the fiber 24. For protection, the camera may be positioned inside the housing 41 of the device 40 adjacent to or above the support base 42, having an observation window or aperture provided in the wall of the housing 41 through which the camera observes the end face 30 of the fiber. The end face 30 of the fiber 24 may have a known position relative to the optical fiber holder 22, for example, if the working end 28 of the fiber 24 is fixed to the optical fiber holder 22 and then cleaved with a suitable cleaving device, and it is conceivable that the end face 30 may be spaced a certain distance from the camera 50 so that the camera 50 can be set up so that the end face 30 is in the camera's focus in the end face view. However, to account for minor errors in the optical fiber and / or cleaving that may not have been cleaved in this manner, an adjustable focusing lens 54 may be provided between the camera 50 and the fiber end 30 so that the focus can be adjusted or corrected by the user (or automated if all or part of the device is computer controlled) so that the end face view of the end face 30 is focused on one or more image capture elements in the camera 50. One or more other lenses or mirrors (not shown) may be included to capture, focus, and / or direct incoming light towards the camera. The camera may capture still images or, more conveniently, continuous images, so that the rotational movement of the optical fiber can be tracked in real time.

[0038]

[0036] The camera 50 outputs image data representing an image of the end face 30. For user observation, the image data may be transmitted to an external monitor connected to the camera. More conveniently, to better enable the use of the device in the field, the device or its support base may include an integrated display screen 52 connected to the camera to receive the output image data and display an image of the current view of the end face of the optical fiber to the user, as shown in Figure 4. Thus, for manual adjustment of the rotational position of the optical fiber, the user can observe the view 28 of the end face of the optical fiber on the display screen 52 and rotate the fiber until the desired rotational direction is achieved while observing the image in real time.

[0039]

[0037] The end-face camera-based observation device 48, as shown in Figure 4, does not include any movable mirrors (for example, which would be necessary if the camera were not aligned with the longitudinal axis of the fiber). This improves the durability and reliability of the device 40 and makes the device 40 more suitable for field use.

[0040]

[0038] Figure 7 shows a schematic diagram of an example of a display screen of the exemplary device of Figure 4. Screen 52 shows an image 70 of an end-face view of an optical fiber 24. In this example, the fiber 24 is an ARF having five spaced-apart clad capillaries. The display screen may also show one or more grid lines or crosshairs 72 to facilitate the positioning of the fiber 24, and the user may rotate the fiber to align the image with one or more grid lines and specify the corresponding fiber position as the desired rotation direction position. For example, if two fibers are rotatably oriented after being placed in a fiber splicing device to be spliced ​​together, the fibers may be rotated until each fiber has a capillary in the same position as indicated by the displayed image. Figure 7 shows a fiber positioned by a capillary located at the "12 o'clock" position and bisected by a vertical grid line passing through the central longitudinal axis of the fiber. The second fiber may be similarly aligned to have the same rotational orientation and held on its individual optical fiber holder once both fibers have been removed from the device and placed in the splicing apparatus.

[0041]

[0039] Depending on the usage of the device, the fiber end can be sufficiently illuminated by ambient light so that a high-quality image is captured by the camera and displayed on the display. To address situations where insufficient light is available, the device may further include a light source to illuminate the working end of the optical fiber for better imaging. In one example, the light source may include one or more light-emitting diodes or bulbs that emit ambient light onto the working end of the optical fiber. The light is reflected from the fiber end into the camera in a normal manner to brighten the photographic subject.

[0042]

[0040] However, illumination and imaging of the fiber end can be improved by detecting light emitted from the fiber end. To enable this, a light source can be positioned to direct light onto the side of the optical fiber. Figure 4 shows a light source 56 that can operate in this manner. The light source 56 can be positioned at any side position relative to the optical fiber, but for safety and protection of the light source 56, it is positioned as shown in Figure 4, set within or below the surface of the support base 42 into which the fiber 24 is received, and depending on the position of the light source 56, it can be positioned to direct illumination light towards the side of the fiber (upward in the depicted example) through an aperture or transparent window 57 where appropriate. Light I emitted from the light source 56 is incident on the side of the fiber 24. A portion of the incident light I is coupled to the cladding and further to the core of the fiber 54 and propagates along the fiber 54 so that it is emitted from the end face 30 toward the camera 50. With respect to some fiber types, the cladding is of a type that transmits light into the cladding so that the illumination light source 56 can be positioned at any point along the length of the fiber on which the illumination light source 56 rests on the support base. For other fiber types, the coating may be opaque or partially opaque, thereby causing the light source 56 to absorb some of the incident light. Therefore, the light source 56 should be positioned to direct light onto the side of the fiber 24 near the end face 30, where the coating is likely to have been removed from the fiber 24. Furthermore, by positioning the light source 56 near the end face 30 of the fiber (regardless of the coating type), illumination of the internal structure of the fiber (e.g., capillaries 14 and 18) is increased relative to the cladding (e.g., cladding 3). This results in the structure of the fiber end being well-illuminated, improving the visibility of the internal fiber structure to enable precise rotational positioning. This arrangement is shown in Figure 4.

[0043]

[0041] Figure 8 shows a flowchart of another exemplary method for rotatably positioning an optical fiber. Many of the steps are the same as those numbered correspondingly in the method in Figure 6 and are therefore not described further. An additional optional step S1a is added after the first step S1, in which the working end of the optical fiber is cleved to produce a cleved end face after the fiber has been placed in the optical fiber holder in step S1. To achieve this, the optical fiber holder is selected to be compatible with both the cleaving device used in step S1a and the optical fiber positioning device in which the optical fiber holder is placed in step S2.

[0044]

[0042] The method also includes an additional optional step S4a in which the terminal face of the optical fiber (or end face if cleaving step S1a was not performed) is observed in an end face view so that the cross-sectional structure of the fiber can be seen by using one of the observation techniques outlined above. Thereafter in step S5, the rotation of the fiber to the desired rotational position may be performed while the end face view of the fiber is being observed or monitored so that it can be easily determined that the desired rotational position of the fiber has been achieved.

[0045]

[0043] The rotatable mounting of the clamp on the support base of the device may provide continuous rotation over more than 360 degrees so that the optical fiber can be positioned from any initial orientation to any rotational orientation. This may be made possible by clamp rotation of 360 degrees in a single direction or by clamp rotation of 180 degrees from the initial orientation in both of two opposite directions (rotation of ±180 degrees). However, for many optical fibers, this range of rotation is not necessary, and the need for rotation only needs to address the rotational symmetry of the assumed fiber type, as for most fiber designs there are two or more rotational orientation positions in which the internal structure is aligned to the desired position. Thus, the clamp may be configured to provide only a limited range of rotation, limited to less than 360 degrees. For fiber structures with double rotational symmetry, such as fibers with polarization-maintaining elements incorporated therein (such fibers may or may not be ARFs), rotation in a range of up to 180 degrees (rotation is limited to 180 degrees or less) is sufficient. However, in practice, small extra rotations, for example, limited to 190 degrees or less or 200 degrees or less, are provided to allow for manufacturing defects and slightly misplaced elements. For ARF designs where all clad capillaries have the same configuration, much smaller ranges may be appropriate. For example, an ARF with six clad capillaries of the same design (as in the example in Figure 1) can be oriented by a maximum rotation of 60 degrees (360 degrees / 6), and an ARF with five clad capillaries can be oriented by a maximum rotation of 72 degrees (360 degrees / 5). To allow for errors, rotation ranges limited to 70 degrees and 80 degrees, respectively, can be allowed. Since rotation in both directions provides more flexibility, these various examples can be implemented through rotation ranges of ±95 degrees, ±100 degrees, ±35 degrees and ±40 degrees. Because the limited rotational capability of the clamp may be easier to implement than full rotation to any angular position, the device can be simplified without including operational performance for many optical fiber designs to which the proposed device and method are most applicable.Other angle ranges of rotation beyond the examples above are not excluded and may be selected according to the intended use of the device.

[0046]

[0044] The devices described herein provide intermediate devices that can be used in conjunction with existing fiber processing equipment for fiber splicing, fiber cleaving and other processes to improve the results that can be obtained from such equipment, for example, reduced loss and improved optical performance of spliced ​​fibers. The devices can be made compact and robust, and therefore convenient for field use, and may also be fast and inexpensive, as they can be implemented with only a few relatively simple parts and elements.

[0047]

[0045] Dedicated single-purpose rotational positioning devices (such as the example in Figure 4 configured to perform rotational positioning of a fiber and not perform any other fiber processing applications) are useful as accessories to existing fiber processing equipment that do not enable rotational positioning, and the principles and configurations described herein may be further implemented as additional features within fiber processing equipment configured for other processing applications such as cleaving or splicing. For example, a fiber cleaving device may be operable to perform cleaving of a fiber, and rotational positioning of the fiber is performed within the cleaving device before and after cleaving. In another example, a fiber splicing device, such as a fusion splicer, may be operable to receive two cleaved fibers before splicing is performed and to perform rotational positioning on one or both fibers.

[0048]

[0046] In place of or in addition to the other examples described herein, some examples include any combination of the following features:

[0049]

[0047] A first alternative example provides a device for positioning an optical fiber, the device comprising a support base and a receiving area on the support base configured to receive an optical fiber holder such that the optical fiber holder is fixed to the support base, the optical fiber holder being for holding an optical fiber, and including a clip that is operable between an open position in which the optical fiber held in the optical fiber holder is movable relative to the optical fiber holder and a closed position in which the held optical fiber is fixed to the optical fiber holder with respect to longitudinal, rotational and transverse movement of the optical fiber, the support base comprising a receiving area configured to enable the clip to move between the open and closed positions when the optical fiber holder is received within the receiving area, and a clamp that is movably mounted on the support base to enable rotation about an axis coinciding with the longitudinal axis of the optical fiber held in the optical fiber holder, and is configured to clamp the optical fiber held in the optical fiber holder when received within the receiving area, and includes an open position in which the optical fiber is not clamped to the support base and a closed position in which the optical fiber is clamped and fixed to the support base with respect to longitudinal and transverse movement of the optical fiber, but is rotatable about the longitudinal axis of the optical fiber.

[0050]

[0048] The clamp may be configured to be rotatable relative to the support base in order to rotate the optical fiber about the longitudinal axis of the optical fiber.

[0051]

[0049] The clamp may be manually rotatable.

[0052]

[0050] The clamp may be configured to rotate the optical fiber over a range limited to less than 360 degrees.

[0053]

[0051] The clamp may be configured to rotate the optical fiber over a range limited to 200 degrees or less.

[0054]

[0052] The device may further include an observation device mounted on a support base, configured to provide an end-face view of the end of an optical fiber held in an optical fiber holder and clamped by a clamp.

[0055]

[0053] The observation device may include a camera capable of capturing an image of the end face view of the end of the optical fiber.

[0056]

[0054] The observation device may further include an adjustable lens that can be operated to focus an end-face view of the end of the optical fiber onto the image capture element of a camera.

[0057]

[0055] The device may further include a display screen configured to display an image of the end face view of the end of the optical fiber captured by the camera.

[0058]

[0056] The device may further include a light source that can operate to illuminate the end of the optical fiber visible by the observation device.

[0059]

[0057] The light source may be positioned to direct the light onto the side surface of the optical fiber, thereby coupling the light through the side surface of the optical fiber for propagation along the optical fiber and emission from the end of the optical fiber toward the observation device. The light source may be positioned to direct the light onto the side surface of the optical fiber closest to the end face (or end face) of the optical fiber.

[0060]

[0058] The light source may include one or more light-emitting diodes.

[0061]

[0059] This device may be configured solely for positioning optical fibers.

[0062]

[0060] The light source can be positioned to direct light onto the side of the optical fiber near the end of the optical fiber.

[0063]

[0061] In addition to positioning the optical fiber, this device may be further configured to process the optical fiber.

[0064]

[0062] In addition to positioning the optical fiber, this device may be configured to cleave or price the optical fiber.

[0065]

[0063] A second example provides a method for positioning an optical fiber, which includes placing the optical fiber in an optical fiber holder and fixing the optical fiber with respect to the optical fiber holder for movement in the longitudinal, transverse and rotational directions of the optical fiber; placing the optical fiber holder on a support base such that the optical fiber holder is fixed to the support base; clamping the optical fiber with a clamp that is movable relative to the support base, which, when closed, fixes the optical fiber with respect to the support base for movement in the longitudinal and transverse directions of the optical fiber, but allows rotation of the optical fiber about its longitudinal axis; releasing the optical fiber from the optical fiber holder for movement relative to the optical fiber holder; rotating the optical fiber about its longitudinal axis to achieve a desired rotational position of the optical fiber; fixing the optical fiber at the desired rotational position relative to the optical fiber holder; and releasing the optical fiber from the clamp.

[0066]

[0064] The optical fiber may include an anti-resonant hollow core optical fiber.

[0067]

[0065] The method may further include observing an end-face view of the end of the optical fiber while the optical fiber is being rotated about its longitudinal axis.

[0068]

[0066] The method may further include cleaving the optical fiber in order to provide a cleaved end adjacent to the optical fiber holder between placing the optical fiber in the optical fiber holder and placing the optical fiber holder on a support base.

[0069]

[0067] Any range or device value described herein may be extended or modified without loss of the desired effect, as will be apparent to those skilled in the art.

[0070]

[0068] While the subject matter has been described in language specific to structural features and / or methodological actions, it should be understood that the subject matter as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

[0071]

[0069] It is understood that the above-described benefits and advantages may relate to one embodiment or to several embodiments. Embodiments are not limited to those that solve any or all of the problems described or that have any or all of the benefits and advantages described. A reference to "an" is understood to refer to one or more of those matters.

[0072]

[0070] The operations of the methods described herein may be performed in any preferred order or simultaneously as necessary. In addition, any individual block may be removed from the Method without departing from the scope of the subject matter described herein. Any aspect of the above examples may be combined with any aspect of any of the other examples described herein to form further examples without losing the desired effect.

[0073]

[0071] The term “including” is used herein to mean including a specified block or element of a method, but such block or element does not include an exclusive list, and the method or apparatus may include a block or element of a method or apparatus.

[0074]

[0072] The above description is given for illustrative purposes only, and it will be understood that various modifications can be made by those skilled in the art. The above specification, examples and data provide a detailed description of the structure and use of exemplary embodiments. Various embodiments have been described above by some degree of specificity or by reference to one or more individual embodiments, but those skilled in the art can make many modifications to the disclosed embodiments without departing from the scope of this specification.

Claims

1. A device (40) for positioning an optical fiber (24), Support base (42), The receiving area (44) on the support base is configured to receive the optical fiber holder (20) so that the optical fiber holder is fixed to the support base, the optical fiber holder is for holding an optical fiber, and includes a clip (32) that is operable between an open position in which the optical fiber held within the optical fiber holder is movable relative to the optical fiber holder and a closed position in which the held optical fiber is fixed relative to the optical fiber holder with respect to longitudinal, rotational and transverse movement of the optical fiber, the support base is configured to allow the clip to move between the open position and the closed position once the optical fiber holder is received within the receiving area, First and second clamps (46, 58) and Includes, The first clamp (46) is positioned to receive the free end (24a) of the optical fiber held in the optical fiber holder and is movably mounted on the support base to allow rotation about an axis coinciding with the longitudinal axis of the optical fiber held in the optical fiber holder, the clamp is configured to clamp the optical fiber held in the optical fiber holder as received within the receiving area, and the clamp is operable between an open position in which the optical fiber is not clamped to the support base and a closed position in which the optical fiber is clamped and fixed to the support base with respect to longitudinal and transverse movement of the optical fiber, but is rotatable about the longitudinal axis of the optical fiber, and The device (40) is positioned on the working end (28) of the optical fiber held in the optical fiber holder and is movable between an open position and a closed position, wherein in the open position the second clamp does not restrict the position of the optical fiber, and when in the closed position the second clamp provides an aperture of a size that accepts the working end (28) of the optical fiber, thereby allowing rotational movement of the fiber within the aperture.

2. The device according to claim 1, wherein the first clamp is configured to be rotatable with respect to the support base in order to rotate the optical fiber about the longitudinal axis of the optical fiber.

3. The device according to claim 2, wherein the first clamp is manually rotatable.

4. The device according to claim 2 or 3, wherein the first clamp is configured to rotate the optical fiber over a range limited to less than 360 degrees.

5. The device according to claim 4, wherein the first clamp is configured to rotate the optical fiber over a range limited to 200 degrees or less.

6. The device according to any one of claims 1 to 5, further comprising an observation device mounted on the support base, configured to provide an end-face view of the end (28) of an optical fiber held in the optical fiber holder and clamped by the first clamp.

7. The observation device according to claim 6, wherein the observation device includes a camera (50) that is operable to capture an image of the end face view of the end of the optical fiber.

8. The observation device according to claim 7, further comprising an adjustable lens (54) that can be operated to focus the end face view of the end of the optical fiber onto the image capture element of the camera.

9. The device according to claim 7 or 8, further comprising a display screen (52) configured to display an image of the end face view of the end of the optical fiber captured by the camera.

10. The device according to any one of claims 6 to 9, further comprising a light source (56) capable of operating to illuminate the end of the optical fiber visible by the observation device.

11. The device according to claim 10, wherein the light source is arranged to direct light onto the side surface of the optical fiber, thereby coupling the light to the optical fiber through the side surface of the optical fiber for propagation along the optical fiber and emission from the end of the optical fiber toward the observation device.

12. The device according to claim 10 or 11, wherein the light source includes one or more light-emitting diodes.

13. The device according to any one of claims 10 to 12, wherein the light source is positioned to direct light onto the side surface of the optical fiber near the end of the optical fiber.

14. A device according to any one of claims 1 to 13, configured solely for positioning an optical fiber.

15. The device according to any one of claims 1 to 13, further configured to process optical fibers in addition to positioning them.

16. The device according to claim 15, configured to position an optical fiber and to cleave or splice an optical fiber.

17. A method for positioning an optical fiber, The optical fiber is placed inside the optical fiber holder, and the optical fiber is fixed to the optical fiber holder with respect to its movement in the longitudinal, transverse, and rotational directions (S1), S2) The optical fiber holder is positioned on the support base such that the optical fiber holder is fixed to the support base, When closed, the optical fiber is fixed to the support base with respect to its longitudinal and transverse movement, but the optical fiber is clamped using a first clamp movable relative to the support base (S3), which allows the optical fiber to rotate about its longitudinal axis, and the optical fiber is clamped using a second clamp movable between an open position and a closed position, wherein in the open position the second clamp does not restrict the position of the optical fiber, and when in the closed position the second clamp provides an aperture of a size that accepts the working end of the fiber, allowing rotational movement of the optical fiber within the aperture, the first clamp is positioned to accept the free end of the optical fiber, and the second clamp is positioned at the working end of the optical fiber. The optical fiber is released from the optical fiber holder for movement relative to the optical fiber holder (S4), In order to achieve the desired rotational position of the optical fiber, the optical fiber is rotated about its longitudinal axis (S5), Fixing the optical fiber with respect to the optical fiber holder at the desired rotational position (S6), (S7) The optical fiber is released from the first and second clamps. A method that includes this.

18. The method according to claim 17, wherein the optical fiber includes an anti-resonant hollow core optical fiber.

19. The method according to claim 17 or 18, further comprising observing an end face view of the end of the optical fiber while the optical fiber is being rotated about its longitudinal axis (S4a).

20. The method according to any one of claims 17 to 19, further comprising cleaving the optical fiber (S1a) between arranging the optical fiber in the optical fiber holder and arranging the optical fiber holder on the support base, in order to provide a cleaved end adjacent to the optical fiber holder.

Images