Fiber collimator opposing system adjustment device and manufacturing method

Abstract

To make it possible to efficiently adjust a rotation angle of MCF or the like constituting a fiber collimator opposing system.SOLUTION: An adjustment device 1 for a fiber collimator opposing system includes an imaging device 10 having an imaging element 12, and an optical path conversion element 20. The optical path conversion element 20 is configured to guide light from each core toward the imaging element 12 so that light emitted from a plurality of cores of a first fiber collimator 2 and light emitted from a plurality of cores of a second fiber collimator 3 do not overlap on the imaging element 12.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an adjusting device for a paired fiber collimator system, and also to a method for manufacturing a paired fiber collimator system using the adjusting device. [Background technology]

[0002] To meet the increasing traffic demands in optical fiber networks, space division multiplexing (SDM) has been proposed, and multicore fiber (MCF) has been proposed as one of the methods. MCF is known to have multiple light-carrying cores in a single optical fiber. It is also known that fiber bundles consisting of multiple single-mode fibers (SMF) with one core can be used as a substitute for MCF.

[0003] To couple the light propagation cores of MCFs, a facing fiber collimator system is typically employed, in which two optically equivalent single lenses 2b, 3b are placed between two MCFs 2a, 3a to be coupled, as shown in FIG. 7 (Patent Document 1). Light emitted from each light propagation core of the first MCF 2a on the output side diverges as it travels through space, but is focused by passing through the first lens 2b, becoming theoretically parallel light and continuing through space. This light is then further focused by passing through the second lens 3b and coupled to each light propagation core of the second MCF 3a on the input side. In this case, when spatially coupling MCFs having a cross-sectional structure in which a central core is provided at the center of a single optical fiber and multiple outer cores are provided around it, the central cores can be positioned so that light enters and exits along the major axes (optical axes) of the two lenses 2b, 3b. Furthermore, with regard to the outer core, imaging between MCFs 2a and 3a is possible due to the effect that light from an object of height h is inverted and imaged at height -h, similar to the imaging of an object called a 4f system (an optical system that transfers an image by connecting the rear focal position and front focal position of a lens) that is achieved by the basic effect of lenses 2b and 3b. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-109887 Summary of the Invention [Problem to be solved by the invention]

[0005] In a typical SMF coupling system, the main causes of loss deterioration are misalignment of the fiber relative to the spatial beam and mismatch in mode field diameter, and these are similar in MCF coupling systems. In addition, a unique issue with MCF coupling systems is the need to adjust the rotation angle of the MCF fiber. Figure 7 shows the results of a theoretical calculation of the relationship between the rotation angle of the outer core of a spatial optical system using MCF and loss. This result shows that the greater the misalignment in the rotation angles of the two MCFs, the greater the loss.

[0006] Conventionally, the rotation angle of an MCF is adjusted by first introducing visible light into the MCF and projecting it onto a screen such as paper, and then roughly adjusting it while visually checking the relative misalignment. The light source is then switched to a communication wavelength, and the optical system is readjusted and combined, while the rotation angle of each MCF is adjusted to minimize loss. However, adjusting the rotation angle of an MCF using this process requires, for example, repeatedly switching the light source while checking the visible light projected onto a screen, which makes it difficult to shorten the manufacturing time of a fiber collimator pair system.

[0007] Therefore, the main object of the present invention is to provide an adjustment device that can efficiently adjust the rotation angle of MCFs and other components that make up a fiber collimator opposed system, and a method for manufacturing a fiber collimator opposed system using the same. [Means for solving the problem]

[0008] The inventors of the present invention have intensively studied means for solving the above-mentioned problems, and have found that by placing an optical path changing element between two opposingly arranged fiber collimators each including an MCF or the like, and guiding the light emitted from each core of the two fiber collimators simultaneously and non-overlappingly to the imaging element of the imaging device, it becomes possible to efficiently adjust the rotation angles of the MCFs or the like when optically coupling them together. Based on this finding, the inventors have conceived that the problems of the prior art can be solved, and have completed the present invention. Specifically, the present invention has the following configuration or steps.

[0009] A first aspect of the present invention relates to an adjusting device 1. The adjusting device 1 according to the present invention is used to adjust a fiber collimator opposed system. Note that the adjusting device 1 according to the present invention does not include the fiber collimator opposed system that is the adjustment target.

[0010] The fiber collimator opposing system to be adjusted includes a first fiber collimator 2 and a second fiber collimator 3 arranged opposite each other. The first fiber collimator 2 includes a first optical fiber 2a and a first lens 2b. The first fiber collimator 2 is arbitrarily selected from two types: a multicore fiber (MFC) having multiple cores, and a fiber bundle in which multiple single-mode fibers (SMF) having one core are bundled. In other words, the first fiber collimator 2 may be either an MFC or a fiber bundle. The first lens 2b is a single lens for collimating light emitted from the end of each core of the first optical fiber 2a. Similarly, the second fiber collimator 3 includes a second optical fiber 3a and a second lens 3b. The second optical fiber 3a is arbitrarily selected from two types: an MFC and a fiber bundle, and has multiple cores corresponding to the cores of the first optical fiber 2a. The second lens 3b is a single lens for collimating the light emitted from the end of each core of the second optical fiber 2b. The first lens 2b also has the function of focusing the collimated light that has passed through the second lens 3b onto each core of the first optical fiber 2a, and similarly, the second lens 3b also has the function of focusing the collimated light that has passed through the first lens 2b onto each core of the second optical fiber 3a.

[0011] Here, the adjustment device 1 according to the present invention includes an imaging device 10 and an optical path changing element 20. The imaging device 10 is, for example, an infrared camera, and has an imaging element 12 that converts incident light into an electrical signal. The optical path changing element 20 is configured to guide light from the first lens 3a and light from the second lens 3b toward the imaging element 12 so that light from each core of the first optical fiber 3a and light from each core of the second optical fiber 3b do not overlap on the imaging element 12. Examples of the optical path changing element 20 include a mirror and a prism.

[0012] As configured above, with the adjustment device 1 according to the present invention, the light from the first and second fiber collimators 2, 3 is simultaneously and non-overlappingly captured by the imaging device 10, thereby making it possible to recognize the relative core arrangement tilt (rotation angle) between the first and second optical fibers 3a, 3b having multiple cores. Therefore, by performing the adjustment work while checking the core arrangement tilt of an actually manufactured opposing fiber collimator system, it becomes possible to adjust the collimators in a short time. Furthermore, all of this adjustment work can be performed by propagating the optical fiber with the communication wavelength actually used, eliminating the need to switch the light source to visible light. Therefore, the alignment time can be further reduced.

[0013] The adjustment device 1 according to the present invention preferably further includes an analysis device 30 having a display unit 35 capable of displaying an image captured by the imaging device 10. A general-purpose personal computer (PC) can be used as the analysis device 30. By using such an analysis device 30, the inclination of the core arrangement of the opposing fiber collimator system can be confirmed in real time. Furthermore, the analysis device 30 can perform various analysis processes on the image captured by the imaging device 10.

[0014] In the adjustment device 1 according to the present invention, the analysis device 30 is preferably configured to be able to acquire coordinate information of light incident on the image pickup element 12 and display it together with the captured image on the display unit 35. By acquiring and displaying the coordinate information of light in this way, the optical fiber alignment work can be performed more accurately.

[0015] In the adjustment device 1 according to the present invention, the analysis device 30 preferably further includes a memory unit 32 and a comparison unit 31h. The memory unit 32 stores information about the reference light incident on the image sensor 12. The comparison unit 31h compares the information about the reference light with information about the light currently incident on the image sensor 12 and outputs the comparison result to the display unit 35. For example, light emitted from an optimally aligned fiber collimator opposed system may be used as the reference light, and information about the reference light may be stored in the memory unit 32. The information about the reference light includes coordinate information about the light on the image sensor 12, information about the length and inclination (angle) of the line connecting the two light beams, and information about the angle formed by the two intersecting lines. The comparison unit 31h compares the information about the reference light with information about the light emitted from the fiber collimator opposed system currently being adjusted, thereby enabling efficient alignment of the fiber collimator opposed system.

[0016] A second aspect of the present invention relates to a method for manufacturing a paired fiber collimator system. The manufacturing method according to the second aspect basically includes a step of aligning two fiber collimators using the adjustment device 1 according to the first aspect described above. Specifically, the manufacturing method according to the present invention includes a step of imaging output light from a first paired fiber collimator system using the adjustment device 1 as reference light, and a step of imaging output light from a second paired fiber collimator system using the adjustment device 1 and adjusting it while comparing it with information about the reference light. [Effects of the Invention]

[0017] According to the present invention, the rotation angle of the MCF and the like that constitute the fiber collimator opposing system can be adjusted efficiently. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 shows a schematic diagram of a fiber collimator facing system and the configuration of an adjustment device used for adjusting the system. [Figure 2]Figure 2(a) shows a schematic diagram of the optical elements that make up the fiber collimator opposing system and the adjustment device, and Figure 2(b) shows a schematic diagram of the focusing position of the light emitted from each core on the imaging element. [Figure 3] FIG. 3 is a block diagram showing an example of functional elements that mainly constitute the analysis device. [Figure 4] Figure 4 shows an example of image processing by the analysis device. [Figure 5] FIG. 5 shows an example of image analysis processing by the analysis device. [Figure 6] FIG. 6 is a schematic diagram showing an example of a method for manufacturing a fiber collimator facing system. [Figure 7] Fig. 7(a) shows a known opposing fiber collimator system, and Fig. 7(b) is a graph showing the known relationship between fiber rotation angle and loss. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and includes appropriate modifications of the embodiments described below within the scope obvious to those skilled in the art.

[0020] 1 shows an outline of an adjustment device 1 according to one embodiment of the present invention. This adjustment device 1 is basically used for aligning a fiber collimator facing system.

[0021] Before describing the adjustment device 1 according to the present invention, the fiber collimator opposed system to be adjusted will be described. Known opposed fiber collimator systems, including the one shown in FIG. 7(a), can be used. The opposed fiber collimator system is composed of two fiber collimators 2 and 3 arranged opposite to each other. Each fiber collimator 2 and 3 includes an MCF 2a and 3a, respectively, having multiple light-propagating cores. In the opposed fiber collimator system, each MCF 2a and 3a has cores of a corresponding number and arrangement, and the cores of each MCF 2a and 3a are optically coupled to each other. Instead of the MCFs 2a and 3a, a fiber bundle formed by bundling multiple SMFs may be used. The MCF and the fiber bundle may also be coupled. The light-propagating core may be a core that propagates single-mode light or a core that propagates multimode light.

[0022] Each fiber collimator 2, 3 includes a lens 2b, 3b for collimating (converting into parallel light) the light diverging at a certain divergence angle from each core of the MCF 2a, 3a. These lenses 2b, 3b also focus the collimated light when it is incident on them. The core of the MCF 2a, 3a is located at the focal position of each lens 2b, 3b. Therefore, the light diverging from the core of the first MCF 2a is collimated by the first lens 2b, then focused by the second lens 3b and incident on the corresponding core of the second MCF 3a. The light diverging from the core of the second MCF 3a is incident on the corresponding core of the first MCF 2a in the reverse order.

[0023] Each fiber collimator 2, 3 has holding members 2c, 3c that hold the MCFs 2a, 3a and the lenses 2b, 3b so as to maintain a constant distance between the end faces of the MCFs 2a, 3a and the lenses 2b, 3b. The MCFs 2a, 3a and the lenses 2b, 3b are fixed to the holding members 2c, 3c, and by rotating the holding members 2c, 3c during alignment, the MCFs 2a, 3a are optically coupled to each other so as to minimize loss.

[0024] Next, a description will be given of the adjustment device 1 according to the present invention. As shown in FIG.

[0025] The imaging device 10 may be a camera capable of capturing light of wavelengths (e.g., 1000 to 2000 nm) used in general optical fiber communications. For example, a known infrared (IR) camera may be used as the imaging device 10. The imaging device 10 basically includes an imaging lens 11 and an imaging element 12 (photoelectric conversion element). The imaging lens 11 focuses light incident on the imaging device 10 onto the imaging element 12. The imaging element 12 is, for example, a CCD image sensor unit, and converts the incident light into an electrical signal. Although not shown, the imaging device 10 may also include electronic components such as a mechanical shutter, a shutter driver, a digital signal processor (DSP) that reads the charge from the imaging element 12 and generates image data, and an IC memory. The image data acquired by the imaging device 10 is output to the analysis device 30.

[0026] The imaging device 10 converts the light emitted from each core into an electrical signal using the imaging element 12, and generates image data based on the amount of charge. The image data shows the light emitted from each core as a dot, as shown in FIG. 2(b), for example. This image data is output from the imaging device 10 to the analysis device 30, where it is subjected to analysis processing. The image data may be a still image or a video at a predetermined frame rate.

[0027] The optical path changing element 20 is disposed on the optical axis between the two fiber collimators 2 and 3 that constitute the opposed fiber collimator system, and is an optical element that changes the optical path of light emitted from each of the MCFs 2a and 3a and guides the light to the imaging lens 11 of the imaging device 10. This optical path changing element 20 is configured to provide optically symmetrical functions to the two MCFs 2a and 3a. In the example shown in FIG. 1 , the optical path changing element 20 is configured by a compound prism. The compound prism has a first reflecting portion 21 that reflects light from the first fiber collimator 2 toward the imaging lens 11, and a second reflecting portion 22 that reflects light from the second fiber collimator 3 toward the imaging lens 11. Here, if the first reflecting portion 21 and the second reflecting portion 22 reflect light at a right angle (90 degrees) to the optical axis of the MCFs 2a and 3a, depending on the core arrangement of the MCFs 2a and 3a, the light emitted from each core may overlap on the imaging element 12 of the imaging device 10, and in that case, the coordinate position of each light may not be properly acquired. For this reason, the first reflecting portion 21 and the second reflecting portion 22 are arranged so that the reflection angle of the light is inclined with respect to the optical axis of the MCFs 2a and 3a so that the light emitted from each core of the MCFs 2a and 3a does not overlap on the imaging element 12 of the imaging device 10. For example, it is preferable that the angle (symbol θ in FIG. 1) at which each reflecting portion 21, 22 reflects light incident along the optical axis (main axis) of MCF 2a, 3a is adjusted to be less than 90 degrees, specifically 80 to 89.8 degrees, 85 to 89.8 degrees, or 87 to 89.5 degrees, relative to the optical axis of MCF 2a, 3a.

[0028] 1, the optical path turning element 20 is configured as a compound prism having two reflecting portions 21 and 22, but is not limited to this, and two mirrors can be arranged instead of the compound prism. Alternatively, an optical element having an optical path turning function, such as a photonic crystal, can also be used as the optical path turning element 20.

[0029] FIG. 2(a) schematically shows the optical paths of light emitted from each core of two MCFs 2a and 3a. As shown in FIG. 2(a), the light emitted from each core of the two MCFs 2a and 3a passes through lenses 2b and 3b, an optical path rotator 20 (compound prism), and an imaging lens 11, respectively, and is collected on the imaging element 12. FIG. 2(b) also schematically shows the collecting positions of the light emitted from each core on the imaging element 12. In the example shown in FIGS. 2(a) and 2(b), each of the two MCFs 2a and 3a has four cores. However, as shown in FIG. 2(b), a total of eight light beams are simultaneously observed on the imaging element 12, and the eight light beams are dispersed so as not to overlap. In this way, in the adjustment device 1 according to the present invention, the optical path rotator 20 and the imaging lens 11 are designed so that all light beams from each core of the two MCFs 2a and 3a are simultaneously and non-overlappingly collected on the imaging element 12. In particular, the reflection angles of the first reflecting portion 21 and the second reflecting portion 22 constituting the optical path changing element 20 are optimized to satisfy these conditions. This makes it possible to individually obtain coordinates on the imaging element 12 for the light emitted from each core.

[0030] 2, the optical path changing element 20 is preferably held by a known slide mechanism (not shown) or the like so that it can be switched between a first arrangement on the optical axis of each MCF 2a, 3a and a second arrangement off this optical axis. As will be described in detail later, after the first and second fiber collimators 2, 3 are optimally adjusted with the optical path changing element 20 arranged on the optical axis of each MCF 2a, 3a, this optical path changing element 20 is removed from the optical axis, and these fiber collimators 2, 3 are fixed by a fixing member or the like without moving.

[0031] The analysis device 30 is a computer in which a predetermined analysis processing program is installed. Fig. 3 shows an example of functional blocks of the analysis device 30. As shown in Fig. 3, the analysis device 30 includes a calculation processing unit 31, a memory unit 32, an input unit 33, an operation unit 34, and a display unit 35.

[0032] The arithmetic processing unit 31 is responsible for performing predetermined calculations and processing for controlling the other elements 32 to 35, and may utilize a processor such as a CPU (Central Processing Unit). The arithmetic processing unit 31 basically reads out programs (including an OS) stored in the storage unit 32, loads them into main memory, and executes predetermined calculations in accordance with these programs. The programs stored in the storage unit 32 include an image analysis program that causes the arithmetic processing unit 31 to execute each of the arithmetic processing functions (reference numerals 31a to 31h) described below. The arithmetic processing unit 31 can also write and read calculation results in accordance with the programs to and from the storage unit 32 as appropriate.

[0033] The memory unit 32 is an element for storing information used in the arithmetic processing and the like in the arithmetic processing unit 31 and the results of the arithmetic processing. The storage function of the memory unit 32 can be realized by a non-volatile memory such as an HDD or an SDD. The memory unit 32 may also function as a main memory for writing or reading the progress of the arithmetic processing by the arithmetic processing unit 31. The memory function of the memory unit 32 can be realized by a volatile memory such as a RAM or a DRAM.

[0034] The input unit 33 is an input device that mainly receives image data from the imaging device 10. The input unit 33 may acquire image data from the imaging device 10 via a wired connection in accordance with a known input / output interface, or may acquire image data from the imaging device 10 via a wireless connection in accordance with a known communication standard. An example of a wired input / output interface is USB (Universal Serial Bus). Examples of wireless standards are Bluetooth (registered trademark) and Wi-Fi. The input unit 33 may also acquire image data from the imaging device 10 via the Internet or an intranet.

[0035] The operation unit 34 is an operating device for receiving operation commands input by a user. Examples of the operation unit 34 include pointing devices such as a mouse, a touch panel, and a trackpad, and character input devices such as a keyboard. The user can input predetermined operation commands to the analysis device 30 via the operation unit 34.

[0036] The display device 34 outputs and displays various information required for the user to use the adjustment device 1 in response to an input signal from the calculation processing unit 31. The display device 34 displays a screen showing, for example, image data, calculation results, etc. Examples of the display device 34 include, but are not limited to, an LCD (Liquid Crystal Display) or an OLED (Organic Electro Luminescence Display), and any known display device can be used.

[0037] Next, the image analysis processing that can be performed by the arithmetic processing unit 31 in this embodiment will be described with reference to Figures 3 to 5. By executing a program stored in the storage unit 32, the arithmetic processing unit 31 functions as an image processing unit 31a, a spot selection unit 31b, a numbering unit 31c, a coordinate measurement unit 31d, a line adding unit 31e, a line analysis unit 31f, a reference holding unit 31g, and a comparison unit 31h, as shown in Figure 3.

[0038] The image processing unit 31a performs predetermined image processing on the image data acquired from the imaging device 10 to process the image data so that it is easier to perform subsequent analysis processing. For example, as shown in FIGS. 4(a) and 4(b), when the image data acquired from the imaging device 10 is expressed in color or grayscale, the image processing unit 31a performs binarization processing to convert this image data into only two colors, white and black, using a predetermined threshold value. In this way, by clarifying the boundary between the bright spots and the background contained in the image data, the processing speed and accuracy of subsequent analysis processing can be improved. In addition, the image processing unit 31a can also perform image processing such as processing to sharpen the contours of bright spots and edge detection processing.

[0039] The spot selector 31b extracts only spots corresponding to the light emitted from each core of the MCF from the image data processed by the image processor 31a. In other words, the image data may contain white dots other than the light emitted from each core. To prevent false detection, an appropriate size range is determined in advance for the spots corresponding to each core, and white dots outside this size range are excluded from the analysis. For example, as shown in Figures 4(b) and 4(c), the spot selector 31b removes white dots smaller than the predetermined size range from the image data. This allows only the spots corresponding to each core to be subjected to subsequent analysis.

[0040] The numbering unit 31c assigns a unique number to each spot extracted by the spot selection unit 31b according to a predetermined rule. For example, in FIG. 4(d), an analysis line is shown as a dotted line. The analysis line is inclined at an arbitrary angle, and when this analysis line is moved from the left side to the right side of the image data, a number is assigned to each spot in the order in which the spots come into contact with this analysis line. In the example of FIG. 4(d), a total of eight spots exist in the image data, and each spot is assigned an identification number from S1 to S8. The identification numbers assigned by the numbering unit 31c may be displayed on the display unit 35 together with the processed image data.

[0041] The coordinate measurement unit 31d measures coordinate information within the image data for spots to which identification numbers have been assigned by the numbering unit 31c. Specifically, as shown in FIG. 4(e), the coordinate measurement unit 31d detects the center of gravity of each spot and determines the x- and y-coordinates of the center of gravity of each spot. The center of gravity coordinates of each spot measured by the coordinate measurement unit 31d may be displayed on the display unit 35.

[0042] The line adding unit 31e adds a line (line segment) connecting the centers of gravity of two specified spots based on the centroid coordinates of each spot calculated by the coordinate measurement unit 31d. The two spots to be connected by a line can be specified by the user selecting the spot identification number via the operation unit 34. Specifically, in the example shown in FIG. 4(f), spots S1 and S7 are connected by line L1, spots S2 and S8 are connected by line L2, spots S3 and S5 are connected by line L3, and spots S4 and S6 are connected by line L4. Alternatively, as shown in FIG. 4(f), an identification number (L1 to L4) may be assigned to each line connecting two spots. The lines added by the line adding unit 31e are displayed on the display unit 35 together with the processed image data. The line adding unit 31e may automatically add a line connecting the centers of gravity of two spots according to a predetermined algorithm, rather than manually by the user.

[0043] The line analysis unit 31f analyzes the lines added by the line adding unit 31e. Examples of line analysis include absolute angle measurement, relative angle measurement, and cross-line analysis. FIG. 5 shows an example of analysis processing by the line analysis unit 31f. As shown in FIG. 5(a), absolute angle measurement is a process of calculating the angle (absolute angle) of each line relative to the x-axis of the image data. As shown in FIG. 5(b), relative angle measurement is a process of calculating the angle (relative angle) between two intersecting lines. The combination of two lines for which the relative angle is to be measured can be specified by the user selecting the line identification numbers via the operation unit 34. Alternatively, the two lines for which the relative angle is to be measured may be automatically selected according to a predetermined algorithm. The relative angle between two lines may be measured by actually measuring the angle based on the lines added to the image data, or may be calculated based on the absolute angles of each line.

[0044] Cross-line analysis is a process in which a plurality of lines are divided into two groups and the lines are compared between the groups. Specifically, as shown in FIG. 5(c), the lines added by the line adding unit 31e are divided into groups. The first group (G1) is made up of line L1 (horizontal line) and line L3 (vertical line), and the second group (G2) is made up of line L2 (horizontal line) and line L4 (vertical line). In the example shown in FIG. 5, the first group (G1) connects the spots of light emitted from the first MCF 2a, and the second group (G2) connects the spots of light emitted from the second MCF 3a. Such grouping of lines can be specified by the user selecting the line identification number via the operation unit 34. Note that, in principle, lines for which relative angles have been calculated in relative angle measurement belong to the same group, so that lines for which relative angle measurement has been performed may be automatically included in the same group.

[0045] Next, in the cross line analysis, a combination of lines that are nearly parallel to each other is identified from the two groups (G1, G2), and the sum of the differences in the line lengths of each combination (cross line parallel difference) is calculated. Specifically, the line analysis unit 31f calculates the cross line parallel difference (Δl1) using the following [Equation 1]. [Formula 1] Δl1==|L1-L2|+|L3-L4| (L1 to L4 represent the lengths of the lines with the same symbols in FIG. 5(c).)

[0046] Similarly, in the crossline analysis, a combination of lines that are nearly orthogonal to each other from the two groups (G1, G2) is identified, and the sum of the differences in the line lengths of each combination (crossline orthogonal difference) is calculated. Specifically, the line analysis unit 31f calculates the crossline orthogonal difference (Δl2) using the following [Equation 1]. [Formula 1] Δl2==|L1-L4|+|L2-L3|

[0047] For example, in a facing fiber collimator system of a multicore fiber with four cores, the core arrangement of both multicores is not actually an ideal square, but is arranged in a diamond or parallelogram shape due to manufacturing errors. For example, if the core arrangement is a diamond with a difference in the length of the two diagonals, the coupling efficiency will be higher if the combination of long and short cores in the two facing fiber collimators also matches. Based on this principle, crossline analysis is used to determine whether the combination of long and short cores in both collimators matches. In other words, if the crossline parallel difference is smaller than the orthogonal difference, the current combination is optimal; if the opposite is true, it can be determined that rotating one of the fibers by 90° would result in the optimal combination.

[0048] The reference storage unit 31g stores the values ​​measured by the coordinate measurement unit 31d and the line analysis unit 31f as reference values ​​in the memory unit 32. That is, a fiber collimator facing system in which the rotation angles of the MCFs 2a and 3a are optimally adjusted is prepared in advance, and measurement is performed using the adjustment device 1 according to the present invention. Specifically, for this fiber collimator facing system, coordinate information of each spot determined by the coordinate measurement unit 31d and information such as the absolute angle, relative angle, crossline parallel difference, and crossline orthogonal difference determined by the line analysis unit 31f can be stored in the memory unit 32 as reference values. Note that for a fiber collimator facing system that has not yet been optimally adjusted, these measurements are not useful as references, so there is no need to store the various measurement values ​​described above in the memory unit 32. However, information about such a fiber collimator facing system that has not yet been optimally adjusted can also be stored in the memory unit 32 separately from the reference values.

[0049] The comparison unit 31f compares the “reference value” stored in the storage unit 32 for the optimally adjusted reference fiber collimator opposed system (first fiber collimator opposed system) with the value (referred to as the “current value”) measured by the coordinate measurement unit 31d and the line analysis unit 31f for the fiber collimator opposed system currently being measured (second fiber collimator opposed system), and outputs the comparison result to the display unit 35. Specifically, the reference value and the current value may be quantitatively compared for information such as the coordinate information of each spot, the absolute angle, the relative angle, the crossline parallel difference, and the crossline orthogonal difference. While checking the comparison result displayed on the display unit 35, the user may adjust the rotation angle of each MCF 2a, 3a so that the current value of the second fiber collimator opposed system approaches the reference value. This allows the rotation angle of the MCF 2a, 3a included in the second fiber collimator opposed system to be efficiently adjusted.

[0050] Next, a method for manufacturing a paired fiber collimator system will be described with reference to Fig. 6. First, as shown in Fig. 5(a), a first paired fiber collimator system including first and second fiber collimators 2', 3' whose rotation angles have been optimally adjusted in advance is prepared. Then, for this first paired fiber collimator system, coordinate information of spots corresponding to light emitted from each core of the MCFs 2a', 3a', as well as information such as absolute angle, relative angle, crossline parallel difference, and crossline orthogonal difference is measured using an adjustment device 1 (including an imaging device 10, an optical path changing element 20, and an analysis device 30) according to this embodiment. The information measured here is stored in the analysis device 30 as reference values.

[0051] After the reference value for the first fiber collimator opposed system has been measured, it is preferable to remove the first fiber collimator opposed system without moving the position of the optical path turning element 20 of the adjustment device 1. For this reason, the first and second fiber collimators 2', 3' may be fixed while maintaining the rotation angle, etc., by a semi-fixed member 4 having a notch in a portion corresponding to the optical path turning element 20.

[0052] Next, as shown in FIG. 6( b), a first paired fiber collimator system is prepared, including the first and second fiber collimators 2 and 3 to be actually adjusted. At this stage, the rotation angles and other parameters of the MCFs 2a and 3a of the first and second fiber collimators 2 and 3 have not yet been fixed. For this second paired fiber collimator system, the same adjustment device 1 used to measure the first paired fiber collimator system is used to measure current values, including coordinate information of the spots corresponding to the light emitted from each core, absolute angle, relative angle, crossline parallel difference, and crossline orthogonal difference. At this time, the display unit of the analysis device 30 displays the comparison result between the current value of the second paired fiber collimator system and the reference value of the first paired fiber collimator system. The rotation angles and other parameters of the MCFs 2a and 3a are then adjusted so that the current value of the second paired fiber collimator system approaches the reference value of the first paired fiber collimator system.

[0053] Finally, as shown in FIG. 6( c), the first and second fiber collimators 2 and 3 with the optimized rotation angles of the MCFs 2a and 3a are fixed by the fixing member 5. At this time, it is preferable to move the optical path changing element 20 from the optical axis of the first and second fiber collimators 2 and 3. This makes it possible to fix the first and second fiber collimators 2 and 3 by the fixing member 5 while maintaining the optimally adjusted positions and orientations of the first and second fiber collimators 2 and 3. In this way, it is possible to efficiently manufacture a paired fiber collimator system with optimally adjusted MCFs 2a and 3a. Furthermore, after returning the position of the optical path changing element 20 to its original position, another paired fiber collimator system can be adjusted. This allows the adjustment of paired fiber collimator systems to be performed continuously.

[0054] In the above description of the present invention, the embodiments of the present invention have been described with reference to the drawings in order to express the contents of the present invention. However, the present invention is not limited to the above embodiments, and includes modifications and improvements that are obvious to those skilled in the art based on the matters described in the present specification. [Explanation of symbols]

[0055] 1...adjustment device 2...first fiber collimator 3... Second fiber collimator 4... Semi-fixed member 5...Fixing member 10...Imaging device 11...imaging lens 12...imaging element 20...optical path conversion element 21...first reflecting portion 22... Second reflecting section 30... Analyzing device

Claims

1. An adjustment device (1) for a fiber collimator opposing system, the fiber collimator opposing system includes a first fiber collimator (2) and a second fiber collimator (3) arranged opposite to each other; the first fiber collimator includes a first optical fiber (2a) arbitrarily selected from two types: a multicore fiber having a plurality of cores, and a fiber bundle in which a plurality of single-mode fibers each having one core are bundled; and a first lens (2b) for collimating light emitted from an end of each core of the first optical fiber, the second fiber collimator includes a second optical fiber (3a) arbitrarily selected from the two types and having a plurality of cores corresponding to the cores of the first optical fiber, and a second lens (3b) for collimating light emitted from an end of each core of the second optical fiber; The adjustment device is an imaging device (10) having an imaging element (12); an optical path conversion element (20) for guiding the light from the first lens and the light from the second lens toward the imaging element so that the light from each core of the first optical fiber and the light from each core of the second optical fiber do not overlap on the imaging element; an analysis device (30) having a display unit (35) capable of displaying an image captured by the imaging device, The analysis device a line providing unit (31e) that provides lines connecting two spots that are manually or automatically designated by a user, such that, for the light spots from each core of the first optical fiber and the light spots from each core of the second optical fiber imaged by the imaging device, a plurality of lines connecting two diagonal spots among the plurality of spots of the first optical fiber intersect each other inside the plurality of spots of the first optical fiber, and a plurality of lines connecting two diagonal spots among the plurality of spots of the second optical fiber intersect each other inside the plurality of spots of the second optical fiber; a line analysis unit (31f) that analyzes the lines added by the line adding unit, The analysis result of the line analysis unit can be displayed on the display unit. Adjustment device for the opposing fiber collimator system.

2. The light from each core of the first optical fiber and the second optical fiber is configured to be simultaneously observed by the imaging element. The adjustment device according to claim 1 .

3. The analysis device is further configured to acquire coordinate information of light incident on the image sensor and display the coordinate information together with the captured image on the display unit. The adjustment device according to claim 1 .

4. The analysis device further comprises: a storage unit (32) for storing information about the reference light incident on the imaging element; a comparison unit (31h) that compares information about the reference light with information about the light currently incident on the imaging element and outputs the comparison result to the display unit. The adjustment device according to claim 1 .

5. A method for manufacturing a fiber collimator opposing system using an adjustment device (1), imaging output light from a first fiber collimator opposing system using the adjustment device as reference light; and a step of imaging the output light of the second fiber collimator opposing system using the adjusting device (1) and adjusting it while comparing it with information about the reference light, the first fiber collimator opposed system and the second fiber collimator opposed system each include a first fiber collimator (2, 2') and a second fiber collimator (3, 3') arranged opposite to each other; the first fiber collimator includes a first optical fiber (2a) arbitrarily selected from two types: a multicore fiber having a plurality of cores, and a fiber bundle in which a plurality of single-mode fibers each having one core are bundled; and a first lens (2b) for collimating light emitted from an end of each core of the first optical fiber, the second fiber collimator includes a second optical fiber (3a) arbitrarily selected from the two types and having a plurality of cores corresponding to the cores of the first optical fiber, and a second lens (3b) for collimating light emitted from an end of each core of the second optical fiber; The adjustment device is an imaging device (10) having an imaging element (12); an optical path conversion element (20) for guiding the light from the first lens and the light from the second lens toward the imaging element so that the light from each core of the first optical fiber and the light from each core of the second optical fiber do not overlap on the imaging element; an analysis device (30) having a display unit (35) capable of displaying an image captured by the imaging device, The analysis device a line providing unit (31e) that provides lines connecting two spots that are manually or automatically designated by a user, such that, for the light spots from each core of the first optical fiber and the light spots from each core of the second optical fiber imaged by the imaging device, a plurality of lines connecting two diagonal spots among the plurality of spots of the first optical fiber intersect each other inside the plurality of spots of the first optical fiber, and a plurality of lines connecting two diagonal spots among the plurality of spots of the second optical fiber intersect each other inside the plurality of spots of the second optical fiber; a line analysis unit (31f) that analyzes the lines added by the line adding unit, The analysis result of the line analysis unit can be displayed on the display unit. A method for manufacturing a fiber collimator opposing system.

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