Optical fiber array, alignment device, mounting board, and optical fiber array alignment method

Abstract

To provide an optical fiber array, an alignment device, a mounting board, and a method for aligning the optical fiber array with which it is possible to reduce the manufacturing cost of the mounting board on which the optical fiber array is mounted.SOLUTION: An optical fiber array 10 comprises: a first optical fiber 11 and a second optical fiber 12 for irradiating a substrate 30 with lights L1, L2 emitted from a light source 21, as well as receiving reflected lights L4, L5 from the substrate which are based on the irradiated lights and guiding the received reflected lights to a first light receiving part 251 and a second light receiving part 261, respectively; and a holder 14 for holding the first and the second optical fibers with a space therebetween.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] In recent years, optical fiber arrays have been developed to facilitate the handling of multiple optical fibers and ensure the mechanical strength of the optical fibers. An optical fiber array is a component in which one or more optical fibers are fixed to a housing.

[0002] The housing of the optical fiber array is processed so that the surface of the housing facing the substrate surface is parallel to the substrate surface when the optical fiber array is tilted so that the light emitted from the optical fibers is incident on the grating coupler (GC) on the substrate at a predetermined angle. Here, the predetermined angle is the incident angle of the light emitted from the optical fibers with respect to the GC at which the conversion efficiency is maximized when the light propagates through the waveguide arranged on the substrate.

[0003] When mounting the optical fiber array on a substrate, the relative positions of the GC and the optical fiber are adjusted to maximize the coupling efficiency between the optical fiber and the GC. Because the surface of the housing facing the substrate surface is processed as described above, when the optical fiber array is tilted to maximize the conversion efficiency, no part of the housing is closer to the substrate surface than the light-emitting ends of the optical fibers. Therefore, this part does not interfere with the adjustment of the relative positions of the optical fiber array and the GC.

[0004] A method for adjusting the relative attitude and position of an optical fiber array with respect to the surface of a substrate is disclosed in Patent Document 1. The method in Patent Document 1 adjusts the relative positions of two optical fibers located at both ends of the optical fiber array with respect to the substrate, and adjusts the horizontality of the optical fiber array with respect to the substrate based on the results of each adjustment. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-5067 Summary of the Invention [Problem to be solved by the invention]

[0006] In the method of Patent Document 1, the relative positions of two optical fibers with respect to the substrate are adjusted in separate steps, one after the other. Therefore, it takes time and effort to adjust the horizontality of the optical fiber array with respect to the substrate. As a result, this leads to an increase in the manufacturing cost of the mounting substrate on which the optical fiber array is mounted.

[0007] An object of the present disclosure is to provide an optical fiber array, an alignment device, a mounting substrate, and an alignment method for an optical fiber array that can reduce the manufacturing cost of a mounting substrate on which an optical fiber array is mounted. [Means for solving the problem]

[0008] An optical fiber array according to one aspect of the present disclosure includes a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from a light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to a first light receiving unit and a second light receiving unit, respectively, and an optical fiber array that is positioned between the first optical fiber and the second optical fiber and inputs light emitted from another light source to an optical integrated circuit arranged on the surface of the substrate. The 3 optical fibers and a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source; and a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while spacing them apart from one another, and the posture in the alignment direction, in which the first optical fiber and the second optical fiber are aligned, is adjusted based on the light reception results of the first light receiving unit and the second light receiving unit, and the posture in the vertical direction, which is the direction perpendicular to the alignment direction, is adjusted based on the detection result of the third detector.

[0009] An alignment device according to one aspect of the present disclosure includes a light source, another light source, a first light receiving unit, a second light receiving unit, a third detector, and a control device, wherein the control device includes a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from the light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to the first light receiving unit and the second light receiving unit, respectively, and a light detector positioned between the first optical fiber and the second optical fiber and inputting the light emitted from the other light source to an optical integrated circuit arranged on the surface of the substrate. The 3 optical fibers and a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source; and a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while spacing them apart. The optical fiber array adjusts its posture in an alignment direction, in which the first optical fiber and the second optical fiber are aligned, based on the light reception results of the first light receiving unit and the second light receiving unit, and adjusts its posture in a vertical direction, which is a direction perpendicular to the alignment direction, based on the detection results of the third detector.

[0010] A mounting substrate according to one aspect of the present disclosure includes the optical fiber array described above and the substrate on which the optical fiber array is attached.

[0011] An alignment method for an optical fiber array according to one aspect of the present disclosure includes a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from a light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to a first light receiving unit and a second light receiving unit, respectively; a third optical fiber located between the first optical fiber and the second optical fiber that inputs light emitted from another light source to an optical integrated circuit arranged on the surface of the substrate; and a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source. and a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while separating them from one another, the optical fiber array irradiates a substrate with light via the first optical fiber and the second optical fiber, and receives reflected light from the substrate based on the light irradiated onto the substrate by the first light receiving unit via the first optical fiber, and receives reflected light from the substrate based on the light irradiated onto the substrate by the second light receiving unit via the second optical fiber, and outputs light from the optical integrated circuit based on the input light. In front Light is received by the third detector, and the attitude of the optical fiber array in the alignment direction, in which the first optical fiber and the second optical fiber are aligned, is adjusted based on the light reception results of the first light receiving unit and the second light receiving unit, and the attitude of the optical fiber array in the vertical direction, which is the direction perpendicular to the alignment direction, is adjusted based on the detection result of the third detector. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide an optical fiber array, an alignment device, a mounting substrate, and an alignment method for an optical fiber array, which can reduce the manufacturing cost of a mounting substrate on which an optical fiber array is mounted. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing an optical fiber array and an alignment device according to a first embodiment; [Figure 2]FIG. 1 is an exploded perspective view showing an optical fiber array according to a first embodiment; [Figure 3] A diagram showing the optical fiber array as seen from the direction A shown in Figure 2. [Figure 4] Plan view of the board without the optical fiber array mounted [Figure 5] 1 is a flowchart showing an alignment operation performed by the alignment device according to the first embodiment of the present disclosure. [Figure 6] 1 is a diagram showing the change over time in the intensity of reflected light during alignment operation, and the change over time in the tilt angle of the bottom surface of the optical fiber array relative to the surface of the substrate. [Figure 7] FIG. 1 is a cross-sectional view of a mounting substrate on which an optical fiber array according to a first embodiment is mounted, showing the vicinity of a grating coupler; [Figure 8] FIG. 10 is a diagram showing an optical fiber array and an alignment device according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing an optical fiber array and an alignment device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Background technology) Silicon photonics is a technology for fabricating photonic integrated circuits (PICs: Photonic ICs) on silicon substrates using microfabrication techniques used in the semiconductor industry. In silicon photonics, waveguides (also called optical waveguides) that conduct light are formed on the substrate. These waveguides play a role equivalent to the wiring in electrical circuits.

[0015] PICs input and output optical signals from and to the outside world by optically coupling with a semiconductor laser element or an optical fiber connected to the semiconductor laser element. Grating couplers (GCs) are frequently used as elements for inputting and outputting optical signals to and from PICs. GCs are elements that have a diffraction grating. GCs are also elements that guide light from outside the waveguide into the inside of the waveguide by being placed on a substrate so that a diffraction grating is provided at the end of the waveguide.

[0016] Generally, GCs are designed to maximize the conversion efficiency of incident light into light propagating through the waveguide (hereinafter referred to as "guided light") when the incident angle of the incident light to the waveguide is a specified angle. For this reason, the optical fiber is mounted on the board at an angle relative to the board surface.

[0017] The PIC has GCs (hereinafter referred to as "incident GCs") that input light into the waveguide, the number of which corresponds to the number of functions that the PIC is to perform. Naturally, some PICs have only one incident GC.

[0018] In order for a PIC to perform independent functions, at least the same number of optical fibers as the functions to be performed must be mounted on the board. Therefore, an optical fiber array is formed to make it easy to handle multiple optical fibers simultaneously.

[0019] In order to mount the optical fiber array on the substrate so as to maximize the conversion efficiency of the light emitted from the optical fibers into guided light, it is necessary to adjust the orientation of the optical fiber array so that the light emitted from each optical fiber of the optical fiber array enters the GC at a predetermined angle.

[0020] The housing of the optical fiber array has a certain dimension in the direction perpendicular to the direction in which the optical fibers are arranged (hereinafter referred to as the arrangement direction). This certain dimension can be as small as several hundred μm or as large as several mm.

[0021] Therefore, when the optical fiber array is tilted so that the incident light from the optical fibers is incident at a predetermined angle to the GC, a part of the housing is closer to the substrate surface than the light-emitting ends of the optical fibers, and this part comes into contact with the substrate surface, which places a limit on how small the distance between the substrate surface and the optical fiber array (hereinafter referred to as the vertical distance) can be reduced.

[0022] Therefore, when the optical fiber array is tilted with respect to the surface of the substrate so that the light emitted from the optical fibers is incident on the GC at a predetermined angle, the housing is processed so that the surface of the housing facing the substrate (hereinafter referred to as the bottom surface) is parallel to the surface of the substrate. Therefore, by adjusting the position of the optical fiber array so that the bottom surface is parallel to the surface of the substrate, the conversion efficiency of the light emitted from the optical fibers to guided light can be maximized.

[0023] Furthermore, to maximize the coupling efficiency between the optical fiber and the GC, it is necessary to adjust the relative positions of the optical fiber and the GC. As described above, by processing the bottom surface, when the orientation of the optical fiber array is adjusted so that the light emitted from the optical fiber is incident on the GC at a specified angle, the bottom surface becomes parallel to the substrate surface, allowing the vertical distance to approach zero. In other words, the relative position of the optical fiber array to the substrate surface can be adjusted without being hindered by the housing.

[0024] Patent Document 1 discloses a method for adjusting the relative posture and position of an optical fiber array with respect to the surface of a substrate. The method of Patent Document 1 has the following features (a) and (b). (a) An optical measurement element for alignment, consisting of a GC and a reflector, is formed on the PIC substrate. (b) The light emitted from the optical fiber is made incident on the optical measurement element for alignment, and the reflected light based on the emitted light and emitted from the GC is received by the optical fiber. Then, the relative position of the optical fiber with respect to the GC is adjusted while measuring the light intensity of the reflected light received by the optical fiber.

[0025] The step of feature (b) is called an alignment operation and is performed using two optical fibers located at both ends of the optical fiber array. Then, the horizontality of the optical fiber array with respect to the substrate is adjusted based on the adjustment results using the two optical fibers.

[0026] When an optical fiber array has multiple optical fibers, the multiple optical fibers are held in a linear arrangement by a housing, and the length of the housing of the optical fiber array in the arrangement direction is about a few millimeters. Therefore, if the bottom surface of the housing of the optical fiber array is tilted in the arrangement direction from being parallel to the substrate surface, part of the housing will be closer to the substrate surface than the light-emitting ends of the optical fibers. This imposes a limit on how small the distance between the substrate surface and the optical fiber array can be, making it difficult to adjust the optical fiber array to an appropriate position relative to the substrate surface.

[0027] The method of Patent Document 1 adjusts the relative distance between the optical fibers located at both ends of the housing and the substrate, thereby making it possible to align the distance between the optical fibers located at both ends of the housing and the substrate, thereby making it possible to make the bottom surface of the housing of the optical fiber array parallel to the surface of the substrate at least in the arrangement direction.

[0028] However, in the method of Patent Document 1, the adjustment of the relative positions of the two optical fibers with respect to the substrate surface is performed sequentially as separate processes. In other words, the alignment operation is performed at least twice. This makes it time-consuming to adjust the tilt of the optical fiber array with respect to the substrate. As a result, this leads to an increase in the manufacturing cost of the mounting substrate on which the optical fiber array is mounted.

[0029] The optical fiber array, alignment device, mounting substrate, and optical fiber array alignment method of the present disclosure can solve such problems.

[0030] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. Note that common components in the drawings will be denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0031] (First embodiment) FIG. 1 is a diagram showing an optical fiber array 10 and an alignment device 20 according to a first embodiment. In the description of this embodiment, the direction perpendicular to a substrate surface 31 (described below) and away from the substrate surface 31 is defined as the positive Z-axis direction. Furthermore, the direction perpendicular to the above-described arrangement direction and parallel to the substrate surface 31, which forms a right-handed coordinate system together with the Z-axis, is defined as the positive X-axis direction. Furthermore, the direction parallel to the substrate surface 31, which forms a right-handed coordinate system together with the X-axis and Z-axis, is defined as the positive Y-axis direction. In FIG. 1, the direction from the back to the front is the positive X-axis direction, the rightward direction is the positive Y-axis direction, and the upward direction is the positive Z-axis direction.

[0032] The optical fiber array 10 is formed by bundling a plurality of optical fibers. The alignment device 20 is a device that adjusts the attitude and position of the optical fiber array 10 relative to the substrate 30.

[0033] <Optical fiber array> FIG. 2 is an exploded perspective view showing the optical fiber array 10 according to the first embodiment.

[0034] The optical fiber array 10 includes a first optical fiber 11, a second optical fiber 12, a third optical fiber 13, and a holder 14.

[0035] 1, the first optical fiber 11 irradiates the substrate 30 with light L1 emitted from the light source 21 of the alignment device 20. The first optical fiber 11 also receives reflected light L4 from the substrate 30 based on the light L1, and guides the reflected light L4 to a first detector 25, which will be described later.

[0036] The second optical fiber 12 irradiates the substrate 30 with light L2 emitted from the light source 21. The second optical fiber 12 also receives reflected light L5 from the substrate 30 based on the irradiated light L2, and guides the reflected light L5 to a second detector 26, which will be described later.

[0037] The third optical fiber 13 is located between the first optical fiber 11 and the second optical fiber 12. The third optical fiber 13 irradiates the substrate 30 with light L3 emitted from another light source 22, which will be described later.

[0038] The number of third optical fibers 13 included in the optical fiber array 10 is the same as the number of GCs 33 (see FIG. 4) arranged on the substrate 30. In this embodiment, the description will be given assuming that there is one GC 33 and one third optical fiber 13 arranged on the substrate 30.

[0039] The holder 14 is a member that holds the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 so that they are spaced apart from one another and aligned in a row.

[0040] As shown in FIG. 2, the holder 14 includes a holder body 15 and a pressing plate 16 .

[0041] The holder body 15 is a housing having a bottom surface 17, a first groove 151, a second groove 152, and a third groove 153. The bottom surface 17 is the surface that faces the substrate surface 31 when the optical fiber array 10 is mounted on the substrate 30.

[0042] The first groove 151, the second groove 152, and the third groove 153 extend from the bottom surface 17 to the surface of the holder body 15 facing the bottom surface 17 (hereinafter referred to as the opposing surface). The first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 are fitted into the first groove 151, the second groove 152, and the third groove 153, respectively, and are arranged so as to lie from the opposing surface to the bottom surface 17.

[0043] The pressing plate 16 is a plate member that is placed over the holder body 15 and has a bottom surface 17 similar to the holder body 15 .

[0044] By aligning the presser plate 16 with the surface of the holder main body 15 on which the first groove 151, the second groove 152, and the third groove 153 are formed (hereinafter referred to as the groove forming surface), the presser plate 16, together with the holder main body 15, can sandwich the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 (see FIG. 3). As a result, the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 are fixed to the holder 14 while aligned in a row.

[0045] The holder 14 is divided into a holder body 15 and a pressing plate 16, so that the optical fiber can be easily attached to the holder 14 compared to the case where the optical fiber is passed through a through-hole in the housing, and the optical fiber can be reliably fixed to the holder 14.

[0046] The bottom surfaces 17, 17 of the holder body 15 and the pressure plate 16 are processed so that the pressure plate 16 is aligned with the groove-forming surface of the holder body 15 and is parallel to the substrate surface 31 when the optical fiber array 10 is mounted on the substrate 30 so that the light emitted from the optical fiber array 10 is incident on the substrate 30 at a predetermined angle.

[0047] <Groove shape> FIG. 3 is a diagram showing the optical fiber array 10 as viewed from the direction A shown in FIG.

[0048] The first groove 151, the second groove 152, and the third groove 153 are shaped such that the width of the groove decreases toward the bottom of the groove. Fig. 3 shows that the shapes of the first groove 151, the second groove 152, and the third groove 153 are triangular when viewed from the bottom surface 17.

[0049] Therefore, even if the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 have slightly different thicknesses, any of the optical fibers can be fixed by sandwiching them between the holder body 15 and the pressing plate 16. In other words, it is not necessary to form grooves or holes in the housing for fixing the optical fibers according to the thickness of each optical fiber.

[0050] The shapes of the first groove 151, the second groove 152, and the third groove 153 may be such that the width dimension becomes shorter toward the bottom of the groove, and when viewing the bottom surface 17, the bottom may be flat or rounded.

[0051] <Tilt angle> 1, α is the tilt angle of the bottom surface 17 relative to the substrate surface 31 in the arrangement direction. The alignment device 20 adjusts the posture of the optical fiber array 10 so that the tilt angle α becomes 0 degrees. As will be described later, the tilt angle of the bottom surface 17 relative to the substrate surface 31 in the vertical direction is assumed to be β.

[0052] <Alignment device> The alignment device 20 includes a light source 21, another light source 22, a branching coupler 23, a circulator 241, a circulator 242, a first detector 25, a second detector 26, an attitude / position adjustment mechanism (not shown), and a control device 27.

[0053] The light source 21 is a device, such as a laser device, that emits light under the control of the control device 27. The light source 21 is connected to the first optical fiber 11 via a branching coupler 23 and a circulator 241. The light source 21 is also connected to the second optical fiber 12 via a branching coupler 23 and a circulator 242.

[0054] The light source 21 irradiates the substrate 30 with light L1 via the branching coupler 23, the circulator 241, and the first optical fiber 11, and also irradiates the substrate 30 with light L2 via the branching coupler 23, the circulator 242, and the second optical fiber 12.

[0055] The other light source 22 is a device that emits light, such as a laser device, under the control of the control device 27. The other light source 22 may be the same type of device as the light source 21, or may be a different type of device from the light source 21.

[0056] The other light source 22 is connected to the third optical fiber 13. The other light source 22 irradiates the substrate 30 with light L3 via the third optical fiber 13.

[0057] The branching coupler 23 is an optical element that branches the light emitted from the light source 21 into two beams at equal ratios. The branching coupler 23 branches the light emitted from the light source 21 into light L1 and light L2. Note that the alignment device 20 may include another optical element instead of the branching coupler 23, as long as it can branch the light emitted from the light source 21 into two beams.

[0058] Circulators 241 and 242 are optical elements that restrict the traveling direction of light, and light input to circulators 241 and 242 can only travel in the directions indicated by the arrows in FIG.

[0059] The circulator 241 receives the light L1 from the branching coupler 23 and outputs it to the first optical fiber 11. The circulator 241 also receives the reflected light L4 from the first optical fiber 11 and outputs it towards the first detector 25.

[0060] The circulator 242 receives the light L2 from the branching coupler 23 and outputs it to the second optical fiber 12. The circulator 242 also receives the reflected light L5 from the second optical fiber 12 and outputs it toward the second detector .

[0061] The alignment device 20 may have other optical elements in place of the circulators 241 and 242, as long as the other optical elements are capable of restricting the direction of travel of light in the same way as the circulators 241 and 242.

[0062] The first detector 25 is a photodetector that includes a first light receiving section 251 that is a light receiving element, and detects the intensity of the reflected light L4 received by the first light receiving section 251.

[0063] The second detector 26 is a photodetector that includes a second light receiving section 261 that is a light receiving element, and detects the intensity of the reflected light L5 received by the second light receiving section 261.

[0064] The attitude / position adjusting mechanism is a device that adjusts the attitude and position of the optical fiber array 10 under the control of the control device 27, and is, for example, a robot.

[0065] The control device 27 performs overall control of the alignment device 20. Specifically, the control device 27 controls the light emission of the light source 21 and the other light source 22, and performs calculation processing based on the detection results of the first detector 25 and the second detector 26. The control device 27 also performs attitude and position adjustment of the optical fiber array 10 via an attitude / position adjustment mechanism (not shown).

[0066] <Substrate> 4 is a plan view of the substrate 30 without the optical fiber array 10 mounted thereon. A waveguide 32, a grating coupler (GC) 33, and an optical integrated circuit 34 are arranged on a substrate surface 31 of the substrate 30.

[0067] The waveguide 32 is a transmission path through which light passes. The GC 33 has a diffraction grating provided at the end of the waveguide, and is an element that propagates light from outside the waveguide 32 into the waveguide 32. The optical integrated circuit 34 is a circuit that processes optical signals. Light from the optical fiber array 10 enters the waveguide 32 via the GC 33, propagates through the waveguide 32, and enters the optical integrated circuit 34 (see the arrow in Figure 4).

[0068] <Alignment operation> 5 and 6, the alignment operation of the alignment device 20 will be described below. In the following description, it is assumed that the alignment device 20 performs the alignment operation fully automatically.

[0069] First, the control device 27 controls the attitude / position adjusting mechanism to bring the optical fiber array 10 close to the substrate surface 31 (step S10).

[0070] Next, the control device 27 controls the light source 21 to start emitting light (step S20). As a result, the light emitted from the light source 21 is split into light L1 and light L2, and the light L1 and light L2 are irradiated onto the substrate 30 via the first optical fiber 11 and the second optical fiber 12, respectively.

[0071] The light L1 and the light L2 are reflected by the substrate 30. Then, the first optical fiber 11 receives the reflected light L4 from the substrate 30 based on the light L1 and guides it to the first light receiving unit 251, and the second optical fiber 12 receives the reflected light L5 from the substrate 30 based on the light L2 and guides it to the second light receiving unit 261.

[0072] The first light receiving unit 251 and the second light receiving unit 261 receive the reflected light L4 and the reflected light L5, respectively. As a result, the first detector 25 and the second detector 26 start to detect the intensity I4 of the reflected light L4 and the intensity I5 of the reflected light L5, respectively.

[0073] Next, the control device 27 adjusts the relative attitude of the optical fiber array 10 based on the light receiving results of the first light receiving section 251 and the second light receiving section 261 (step S30). Step S30 will be described in detail below.

[0074] The control device 27 calculates the difference ΔI between the intensity I4 detected by the first detector 25 and the intensity I5 detected by the second detector 26. Then, the control device 27 adjusts the attitude of the optical fiber array 10, i.e., the tilt angle α, so as to reduce the difference ΔI. The control device 27 continues to adjust the attitude of the optical fiber array 10 until the difference ΔI becomes equal to or smaller than a predetermined value. The predetermined value is set to be greater than 0 mW and sufficiently small.

[0075] Fig. 6 shows the time variations in the intensity I4 of the reflected light L4 and the intensity I5 of the reflected light L5 during the alignment operation, as well as the time variations in the tilt angle α of the bottom surface 17 of the optical fiber array 10 relative to the substrate surface 31. Fig. 6 shows that as the difference ΔI decreases, the tilt angle α approaches 0 degrees. In other words, the difference ΔI and the tilt angle α have a relationship such that the smaller the difference ΔI, the smaller the tilt angle α.

[0076] Next, the control device 27 determines whether the difference ΔI is equal to or smaller than a predetermined value (step S40). If it is determined that the difference ΔI remains greater than the predetermined value (NO in step S40), the control device 27 continues adjusting the attitude of the optical fiber array 10 (step S30).

[0077] If it is determined that the difference ΔI is equal to or smaller than the predetermined value (YES in step S40), the control device 27 controls the attitude / position adjustment mechanism to move the optical fiber array 10 near the GC 33 (step S50). In step S50, the control device 27 moves the optical fiber array 10 so that the third optical fiber 13 of the optical fiber array 10 is positioned opposite the GC 33.

[0078] Next, the control device 27 controls the attitude / position adjusting mechanism to adjust the relative position of the optical fiber array 10 with respect to the substrate surface 31 (step S60). Step S60 will be described below.

[0079] First, the control device 27 controls the other light source 22 to emit light L3. The third optical fiber 13 irradiates the light L3 emitted from the other light source 22 onto the GC 33 of the substrate 30. The light L3 enters the waveguide 32 from the GC 33, propagates through the waveguide 32, and is input to the optical integrated circuit 34. Upon receiving the light L3, the optical integrated circuit 34 emits light based on the light L3. The control device 27 detects the intensity of the light from the optical integrated circuit 34 based on the light L3 using a third detector (not shown), which is a photodetector, and adjusts the position of the optical fiber array 10 in the X-axis, Y-axis, and Z-axis directions so that the intensity detected by the third detector is maximized.

[0080] Furthermore, the control device 27 adjusts the attitude of the optical fiber array 10 in the vertical direction so that the intensity detected by the third detector is maximized. As a result of adjusting the attitude of the optical fiber array 10 in the vertical direction by the control device 27, when the intensity detected by the third detector is maximized, the tilt angle β of the bottom surface 17 with respect to the substrate surface 31 in the vertical direction becomes approximately 0 degrees. In other words, the bottom surface 17 becomes parallel to the substrate surface 31 in the vertical direction. Therefore, by performing the process of step S30 and the attitude adjustment of step S60, the bottom surface 17 becomes parallel to the substrate surface 31.

[0081] In step S40, the control device 27 may determine whether the difference ΔI is 0 mW or not, and if the difference ΔI is 0 mW, execute the process of step S50.

[0082] The control device 27 may also include an input unit (not shown) that accepts input of instructions, and may perform the alignment operation shown in Fig. 3 based on instructions input via the input unit. At that time, the control device 27 may display the intensities I4 and I5, as well as the difference ΔI, on a display unit (not shown) of the alignment device 20.

[0083] <Creating a mounting board> After the orientation and position of the optical fiber array 10 relative to the substrate surface 31 are adjusted by the above-described alignment operation, the optical fiber array 10 is mounted on the substrate 30 to produce a mounting substrate 40.

[0084] An adhesive 41 is used to mount the optical fiber array 10 on the substrate 30. The adhesive 41 is applied between the GC 33 and the holder 14 of the optical fiber array 10, and the applied adhesive 41 is cured to attach the optical fiber array 10 to the substrate 30. In this embodiment, the adhesive 41 is made of a resin material that transmits light. However, the adhesive 41 does not necessarily have to be a resin material, and any type of adhesive may be used as long as it is made of a material that transmits light.

[0085] As a result, a mounting substrate 40 is produced as shown in Fig. 7. Fig. 7 is a cross-sectional view of the mounting substrate 40 on which the optical fiber array 10 is mounted, showing the vicinity of the GC 33.

[0086] The mounting substrate 40 includes the optical fiber array 10, the substrate 30, the waveguide 32, the GC 33, and the optical integrated circuit 34, but the waveguide 32 and the optical integrated circuit 34 are not shown in Fig. 7. Also, Fig. 7 shows the optical fiber array 10 and the GC 33, and the optical fiber array 10 and the substrate surface 31 as being in contact with each other, but in reality they are not in contact with each other.

[0087] When it is determined in step S40 that the difference ΔI is equal to or smaller than the predetermined value, the bottom surface 17 of the holder 14 is parallel to the substrate surface 31 in the arrangement direction. Therefore, at least in the arrangement direction, a portion of the holder 14 can be prevented from coming closer to the substrate surface 31 than the light-emitting ends of the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13. Therefore, the relative position adjustment performed in step S60 reduces the possibility that the portion of the holder 14 will come into contact with the substrate surface 31 when the optical fiber array 10 is brought closer to the substrate surface 31. In other words, the possibility that the portion of the holder 14 will interfere with the adjustment of the relative position of the optical fiber array 10 with respect to the substrate surface 31 can be reduced. Note that, in step S60, the relative attitude adjustment of the optical fiber array 10 in the vertical direction may be performed before the relative position adjustment of the optical fiber array 10. In this case, the relative attitude adjustment and the relative attitude adjustment performed in step S30 result in the bottom surface 17 being parallel to the substrate surface 31 in both the arrangement direction and the vertical direction. That is, when the adjustment of the relative position of the optical fiber array 10 is started, the bottom surface 17 is parallel to the substrate surface 31. Therefore, in the relative position adjustment of step S60, when the optical fiber array 10 is brought close to the substrate surface 31, the possibility that a part of the holder 14 will come into contact with the substrate surface 31 can be further reduced. That is, the possibility that the part will interfere with the adjustment of the relative position of the optical fiber array 10 with respect to the substrate surface 31 can be further reduced.

[0088] According to this embodiment, light L1 and light L2 are irradiated onto the substrate 30 via the first optical fiber 11 and the second optical fiber 12 located at both ends of the optical fiber array 10. Then, the first light receiving unit 251 and the second light receiving unit 261 receive reflected light L4 and reflected light L5 based on the light L1 and the light L2, respectively.

[0089] Therefore, the intensity I4 of the reflected light L4 and the intensity I5 of the reflected light L5 can be detected simultaneously. Therefore, by simply changing the inclination of the optical fiber array 10 based on the intensity I4 of the reflected light L4 and the intensity I5 of the reflected light L5 and the difference ΔI, the optical fiber array 10 can be adjusted to have an appropriate posture with respect to the substrate surface 31 at least in the alignment direction.

[0090] That is, the relative orientation of the optical fiber array 10 with respect to the substrate surface 31 can be adjusted without requiring many steps. Therefore, the time required to adjust the orientation of the optical fiber array 10 can be shortened, and the labor required for the adjustment can be reduced. Consequently, the manufacturing cost of the mounting substrate 40 can be reduced.

[0091] In this embodiment, the reflected light L4 and the reflected light L5 are detected by the first detector 25 and the second detector 26. Therefore, the relative attitude of the optical fiber array 10 can be adjusted in a short time with little effort using simple photodetectors.

[0092] (Second embodiment) The alignment apparatus 20 according to the second embodiment will be described below, focusing mainly on the differences from the first embodiment.

[0093] The alignment apparatus 20 according to the second embodiment includes a balance detector 28 instead of the first detector 25 and the second detector 26.

[0094] The balanced detector 28 is a differential amplification type photodetector. The balanced detector 28 includes a first light receiving unit 251 and a second light receiving unit 261 having photodiodes with balanced characteristics. The balanced detector 28 is configured so that light of opposite polarity is input to the first light receiving unit 251 and the second light receiving unit 261. That is, the reflected light L4 is input to the first light receiving unit 251, and the reflected light L5 is input to the second light receiving unit 261 as light whose polarity is inverted relative to the reflected light L4.

[0095] Therefore, the balance detector 28 detects the combined light of the reflected light L4 received by the first light-receiving unit 251 and the reflected light L5 received by the second light-receiving unit 261, i.e., the light resulting from the mutual cancellation of the reflected light L4 and the reflected light L5. In other words, the balance detector 28 detects a differential signal SG45 between the optical signal SG4 based on the reflected light L4 and the optical signal SG5 based on the reflected light L5. The control device 27 adjusts the attitude of the optical fiber array 10 so that the intensity I45 of the differential signal SG45 detected by the balance detector 28 is reduced.

[0096] Both the light L4 and the light L5 propagating through the first optical fiber 11 and the second optical fiber 12 are affected by common mode noise. Therefore, the reflected light L4 and L5 received by the first light receiving unit 251 and the second light receiving unit 261, respectively, contain common mode noise components. Therefore, in the first embodiment, the intensity I4 of the light L4, the intensity I5 of the light L5, and the difference ΔI all contain common mode noise components.

[0097] According to this embodiment, a balance detector 28 is used to detect a differential signal SG45 between an optical signal SG4 based on the reflected light L4 and an optical signal SG5 based on the reflected light L5. The differential signal SG45 detected by the balance detector 28 corresponds to the result of the reflected light L4 and the reflected light L5 canceling each other out, minimizing the common-mode noise component contained in the intensity I45 of the differential signal SG45. In other words, optical detection associated with the alignment operation can be performed with a high S / N ratio. Therefore, the tilt angle α can be measured with high accuracy, allowing the bottom surface 17 of the holder 14 of the optical fiber array 10 to be aligned parallel to the substrate surface 31 with higher accuracy. This in turn allows for more accurate adjustment of the attitude and position of the optical fiber array 10 relative to the substrate surface 31.

[0098] (Third embodiment) The alignment apparatus 20 according to the third embodiment will be described below, focusing mainly on the differences from the first embodiment.

[0099] The alignment device 20 according to this embodiment does not have another light source 22. Moreover, the alignment device 20 according to this embodiment includes a multi-branch coupler 29 instead of the branch coupler 23, and the light source 21 is connected to the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13 via the multi-branch coupler 29.

[0100] The multi-branching coupler 29 branches the light from the light source 21 and guides light L1, light L2, and light L3 to the first optical fiber 11, the second optical fiber 12, and the third optical fiber 13, respectively. This allows the light source 21 to irradiate the light L3 onto the substrate 30 via the third optical fiber 13.

[0101] According to this embodiment, the light source 21 can also be used as the light source used in the process of step S60. Therefore, the relative attitude and position adjustment of the optical fiber array 10 with respect to the substrate surface 31 can be performed without the need for multiple light sources. This reduces the manufacturing cost of the alignment device 20.

[0102] (Other variations) The optical fiber array 10 does not necessarily have to include the third optical fiber 13. In this case, light is irradiated onto the GC 33 via the first optical fiber 11 or the second optical fiber 12 instead of the third optical fiber 13. [Industrial Applicability]

[0103] The optical fiber array, alignment device, mounting substrate, and alignment method for an optical fiber array according to the present disclosure can be suitably used to adjust the relative orientation of an optical fiber array with respect to a substrate on which it is mounted. [Explanation of symbols]

[0104] 10 Optical fiber array 11 First Optical Fiber 12 Second Optical Fiber 13 The third optical fiber 14 Holder 15 Holder body 151 First Groove 152 Second Groove 153 Third Groove 16 Retaining plate 17 Bottom 20 Alignment device 21 Light source 22 Other Light Sources 23 Branch coupler 241 Circulator 242 Circulator 25 First detector 251 First light receiving unit 26 Second detector 261 Second light receiving unit 27 Control Device 28 Balance Detector 29 Multi-branch coupler 30 boards 31 Substrate surface 32 Waveguide 33 Grating Coupler 34 Optical Integrated Circuits 40 Mounting board 41 Adhesive L1, L2, L3 light L4, L5 reflected light I4, I5, I45 strength SG4, SG5, SG45 optical signal ΔI difference α, β tilt angle

Claims

1. a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from a light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to a first light receiving unit and a second light receiving unit, respectively; a third optical fiber located between the first optical fiber and the second optical fiber, for inputting light emitted from another light source into an optical integrated circuit disposed on the surface of the substrate; a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source; a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while separating them from one another; Equipped with an attitude of the first optical fiber and the second optical fiber in an arrangement direction, which is a direction in which the first optical fiber and the second optical fiber are arranged, is adjusted based on the light receiving results of the first light receiving unit and the second light receiving unit; An optical fiber array, the orientation of which is adjusted in a vertical direction that is a direction perpendicular to the arrangement direction, based on the detection result of the third detector.

2. 2. The optical fiber array according to claim 1, wherein the orientation of the optical fiber array in the alignment direction is adjusted so that the difference between the intensity of the reflected light received by the first light receiving unit and the intensity of the reflected light received by the second light receiving unit is reduced.

3. 2. The optical fiber array according to claim 1, wherein the orientation of the optical fiber array in the arrangement direction is adjusted so that the intensity of the differential signal between the optical signal based on the reflected light received by the first light receiving unit and the optical signal based on the reflected light received by the second light receiving unit is reduced.

4. 2. The optical fiber array according to claim 1, wherein the attitude of the optical fiber array in the vertical direction is adjusted so that the intensity detected by the third detector is maximized.

5. 2. The optical fiber array of claim 1, wherein the holder comprises a holder body having a first groove into which the first optical fiber fits, a second groove into which the second optical fiber fits, and a third groove into which the third optical fiber fits, and a pressure plate that clamps the first optical fiber, the second optical fiber, and the third optical fiber together with the holder body.

6. 6. The optical fiber array according to claim 5, wherein widths of the first groove, the second groove, and the third groove decrease toward their bottoms.

7. 2. The optical fiber array according to claim 1, wherein said light source and said other light source are the same light source.

8. light source, Other light sources, a first light receiving unit; a second light receiving unit; a third detector; and control device, Equipped with The control device a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from the light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to the first light receiving unit and the second light receiving unit, respectively; a third optical fiber located between the first optical fiber and the second optical fiber, for inputting the light emitted from the other light source into an optical integrated circuit disposed on the surface of a substrate; a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source; a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while separating them from one another, and adjusts the posture of the optical fiber array in an arrangement direction in which the first optical fiber and the second optical fiber are arranged based on the light reception results of the first light receiving unit and the second light receiving unit; adjusting an attitude in a vertical direction, which is a direction perpendicular to the arrangement direction, based on a detection result of the third detector; Alignment device.

9. 9. The alignment apparatus according to claim 8, wherein the light source and the other light source are the same light source.

10. 10. The alignment device according to claim 8 or 9, further comprising: a first detector that detects the intensity of the reflected light received by the first light receiving unit; and a second detector that detects the intensity of the reflected light received by the second light receiving unit.

11. 9. The alignment device according to claim 8, further comprising a balance detector that detects a differential signal between an optical signal based on the reflected light received by the first light receiving unit and an optical signal based on the reflected light received by the second light receiving unit based on the light receiving result of the first light receiving unit and the light receiving result of the second light receiving unit.

12. 9. The alignment device according to claim 8, wherein the attitude in the vertical direction is adjusted so that the intensity detected by the third detector is maximized.

13. The optical fiber array according to any one of claims 1 to 7, and the substrate on which the optical fiber array is attached; A mounting board comprising:

14. a first optical fiber and a second optical fiber that irradiate a substrate with light emitted from a light source, receive light reflected from the substrate based on the irradiated light, and guide the received reflected light to a first light receiving unit and a second light receiving unit, respectively; a third optical fiber that is located between the first optical fiber and the second optical fiber and inputs light emitted from another light source to an optical integrated circuit arranged on the surface of the substrate; a third detector that detects the intensity of light from the optical integrated circuit based on the light emitted from the other light source; and a holder that holds the first optical fiber, the second optical fiber, and the third optical fiber while separating them from each other, the first light receiving unit receives reflected light from the substrate based on the light irradiated onto the substrate via the first optical fiber, the second light receiving unit receives reflected light from the substrate based on the light irradiated onto the substrate via the second optical fiber, and the third detector receives emitted light from the optical integrated circuit based on the input light; adjusting the attitude of the optical fiber array in an arrangement direction in which the first optical fiber and the second optical fiber are arranged based on the light receiving results of the first light receiving unit and the second light receiving unit; an alignment method for an optical fiber array, the method comprising adjusting the attitude of the optical fiber array in a vertical direction perpendicular to the arrangement direction based on the detection result of the third detector;

15. adjusting the attitude of the optical fiber array so that a difference between the intensity of the reflected light received by the first light receiving unit and the intensity of the reflected light received by the second light receiving unit becomes small; 15. The method for aligning an optical fiber array according to claim 14.

16. adjusting the attitude of the optical fiber array so that the intensity of a differential signal between an optical signal based on the reflected light received by the first light-receiving unit and an optical signal based on the reflected light received by the second light-receiving unit becomes small; 15. The method for aligning an optical fiber array according to claim 14.

17. 17. The alignment method according to claim 14, further comprising adjusting an attitude in a vertical direction perpendicular to the arrangement direction so that the intensity detected by the third detector is maximized.

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