Misalignment detection device, alignment device, and misalignment detection method

Abstract

To efficiently align opposing optical paths.SOLUTION: The vibrator vibrates a first optical member in a second direction orthogonal to a first direction at a predetermined frequency, the first optical member transmitting input reference light in the first direction through a first optical path and outputting the reference light to a second optical path provided in a second optical member and transmitting light in the first direction. The light receiving means outputs a detection signal indicating a detection result of the reference light input via the second optical path of the second optical member. The calculator calculates the positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the component of the predetermined frequency of the detection signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a positional deviation detection device, an alignment device, and a positional deviation detection method. [Background technology]

[0002] When assembling an optical module, a technique is used to align an optical element or an optical fiber while controlling the position of the other optical element or optical fiber with high precision. As an alignment technique, for example, a method of adjusting the position of an optical fiber to be aligned so that the intensity of a reference light passing through the optical fiber to be aligned is maximized is widely known.

[0003] Also, a method has been proposed for detecting the direction of deviation of an optical fiber based on the phase of a reference light that has passed through a vibrated optical fiber (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-313075 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when aligning two optical waveguides, it is difficult to estimate the amount of misalignment in the direction perpendicular to the extension direction of the optical waveguides based on the results of receiving the reference light. Therefore, to keep the amount of misalignment within a specified range, the received intensity of the reference light must be monitored while changing the position of the optical waveguide. As a result, aligning the optical waveguides requires a significant amount of time. [Means for solving the problem]

[0006] The positional deviation detection device according to the present disclosure comprises: a vibration means for vibrating a first optical element, which transmits input reference light in a first direction through a first optical path and outputs the light to a second optical element provided in the second optical element for transmitting light in the first direction, in a second direction perpendicular to the first direction at a predetermined frequency; a light receiving means for outputting a detection signal indicating a detection result of the reference light input through the second optical element's second optical path; and a calculation means for calculating the positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the predetermined frequency component of the detection signal.

[0007] A positional deviation detection method according to the present disclosure includes: transmitting an input reference light in a first direction through a first optical path; outputting the input reference light to a second optical path provided in a second optical member that transmits light in the first direction; vibrating the first optical member in a second direction perpendicular to the first direction at a predetermined frequency; detecting the reference light input through the second optical path of the second optical member; outputting a detection signal indicating the detection result; and calculating a positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the predetermined frequency component of the detection signal. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to efficiently align opposing optical paths. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating a configuration of a positional deviation detection device according to an embodiment; [Figure 2] FIG. 1 is a diagram illustrating the vibration range of an optical fiber. [Figure 3] 10A and 10B are diagrams illustrating an example of a detection signal and a Fourier transform result of the detection signal. [Figure 4] 10A and 10B are diagrams illustrating examples of the magnitude of peaks corresponding to the product of positional deviation and vibration amplitude. [Figure 5] FIG. 10 is a diagram illustrating a modification of the positional deviation detection device according to the embodiment. [Figure 6] FIG. 1 is a diagram showing the relationship between the vibration direction and frequency of an optical fiber. [Figure 7] 10A and 10B are diagrams illustrating an example of a detection signal and a Fourier transform result of the detection signal. [Figure 8] 1 is a diagram illustrating a configuration of an alignment device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same elements are designated by the same reference numerals, and redundant explanations will be omitted as necessary.

[0011] When referring to one embodiment below, it means that the present invention can be applied to any one of the embodiments described below or a combination of two or more embodiments, and is not limited to a specific embodiment.

[0012] Embodiment 1 The positional deviation detecting device according to the present embodiment is configured to calculate a positional deviation, which is a deviation between the axis of an optical waveguide formed in an optical circuit and the axis of an optical fiber when the optical fiber is coupled to the optical circuit. The optical circuit may be configured as, for example, a silicon photonics (SiP) circuit formed on a silicon substrate.

[0013] Fig. 1 is a diagram schematically illustrating the configuration of a positional deviation detection device according to one embodiment. Here, an example will be described in which the positional deviation detection device 10 calculates a positional deviation when an optical fiber 100 extending in the horizontal direction of the paper surface of Fig. 1 is coupled to an opposing optical circuit 200. The positional deviation detection device 10 has a vibration unit 1, a light receiving unit 2, and a calculation unit 3.

[0014] Reference light L input from a light source (not shown) is transmitted to the optical fiber 100. The light transmitted through the optical fiber 100 is input to an optical waveguide 201 provided in the optical circuit 200. The optical circuit 200 then outputs the reference light L transmitted through the optical waveguide 201 to an optical fiber 300 coupled to the opposite side of the optical fiber 100.

[0015] Hereinafter, the optical fiber 100 will also be referred to as a first optical member having a first optical path. Here, the first optical path refers to a path through which the reference light L is transmitted in the first optical member. The optical circuit 200 will also be referred to as a second optical member having an optical waveguide 201, which is a second optical path. Here, the second optical path refers to a path through which the reference light L is transmitted in the second optical member.

[0016] In addition, in FIG. 1, the horizontal direction from left to right on the paper is the Z direction. The vertical direction from bottom to top on the paper is the X direction. The vertical direction from back to front on the paper is the Y direction. In other words, the X, Y, and Z directions are directions along the X-axis, Y-axis, and Z-axis, respectively, in a Cartesian coordinate system. The Z direction is also called the first direction. The X direction is also called the second direction. The Y direction is also called the third direction.

[0017] The vibrating unit 1 vibrates the optical fiber 100 in a direction perpendicular to the Z direction, which is the extension direction. Here, the vibrating unit 1 vibrates the optical fiber 100 in the X direction, which is the direction perpendicular to the paper surface. The vibrating unit 1 may be configured as, for example, a drive mechanism that drives the optical fiber 100 in the X direction using a motor. However, the vibrating unit 1 is not limited to this, and may be any of various vibration means that can vibrate the optical fiber 100 in a desired direction. Here, the vibrating unit 1 vibrates the optical fiber 100 in the X direction at a frequency f by reciprocating the optical fiber 100 in the X direction within a certain range. X Vibrate with.

[0018] The light receiving unit 2 outputs a detection signal DET indicating the intensity of the reference light L output to the optical fiber 300. The light receiving unit 2 may be configured, for example, by combining a photodiode and a transimpedance amplifier. Note that the configuration of the light receiving unit 2 is not limited to this, and other configurations may be used as appropriate as long as the light receiving unit 2 is capable of outputting a detection signal indicating the intensity of the received light.

[0019] The calculation unit 3 calculates the positional deviation δ in the X direction between the optical fiber 100 and the optical waveguide 201 of the optical circuit 200 based on the detection signal DET.

[0020] The calculation principle of the positional shift δ of the optical fiber 100 in the calculation unit 3 will be described below. The spot size of the reference light L in the optical fiber 100, which is the 1 / e2 width, is defined as w1. The spot size of the reference light L in the optical waveguide 201 in the optical circuit 200, which is the 1 / e2 width, is defined as w2. In this case, the coupling between the optical fiber 100 and the optical waveguide 201 is expressed by the following equation.

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number

number

number

[0021] Based on the following formula, we take the logarithm of η as f(t) below.

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number

number

[0022] Next, the optical fiber 100 is irradiated in the X direction with a frequency f X Hereinafter, the amount of misalignment between the axis of the optical fiber 100 and the axis of the optical waveguide 201 that varies over time due to vibration will be referred to as the axis misalignment δ, and the amount of misalignment that is the vibration center of the axis misalignment δ that does not vary over time due to vibration will be referred to as the position misalignment B. In this case, the axis misalignment δ in the X direction of the optical fiber 100 can be defined by the following equation.

number

[0023] The square of the axis misalignment δ is expressed by the following equation.

number

number

[11] is obtained from equation [9].

number

[0024] Substituting equation

[11] into equation [6] gives the following equation:

number

number

number

number

[0025] Next, f(t) in equation

[12] is Fourier transformed.

number

number

number

[16] can be transformed as follows:

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[0026] As mentioned above, G is a value proportional to the amplitude A of the axial misalignment δ of the optical fiber. H is a value proportional to the product of the amplitude A of the axial misalignment δ of the optical fiber 100 and the positional misalignment B. Therefore, when equation

[19] is plotted in frequency space, X A peak appears with a magnitude proportional to the product of the amplitude A of the axial misalignment δ of the optical fiber 100 and the positional misalignment B, centered at frequency 2f X A peak appears whose magnitude is proportional to the amplitude A of the axial misalignment δ of the optical fiber 100, with the center at .

[0027] 3 is a diagram showing an example of a detection signal and a Fourier transform result of the detection signal. X10 is a graph showing the time variation of the detection signal when the optical fiber 100 is vibrated in the X direction at 1 Hz. The intensity of the detection signal DET changes periodically in accordance with the vibration of the optical fiber 100.

[0028] The graph at the bottom of Figure 3 shows the results of the Fourier transform of the detection signal. As shown in the figure, a peak appears at f = 1 Hz, which corresponds to the product of the positional deviation and the amplitude of the vibration. Also, a peak appears at f = 2 Hz, which corresponds to the amplitude of the vibration.

[0029] As described above, the peak corresponding to the product of the positional shift and the amplitude of the vibration is a peak proportional to the magnitude of the positional shift B. FIG. 4 is a diagram showing an example of the magnitude of the peak corresponding to the product of the positional shift and the amplitude of the vibration. As shown in FIG. 4, it can be seen that the magnitude of the peak corresponding to the product of the positional shift B and the amplitude of the vibration varies depending on the magnitude of the positional shift B.

[0030] Therefore, the frequency f X By estimating the value of H from the magnitude of the peak at this position, the positional deviation B of the optical fiber 100 with respect to the optical waveguide of the optical circuit 200 can be calculated.

[0031] For example, using the same type of optical fiber as the optical fiber 100, the frequency f X The magnitude of the peak at the frequency f measured for the optical fiber 100 to be measured may be measured in advance to obtain reference data. X The positional deviation B of the optical fiber 100 may be calculated by comparing the peak with a reference peak acquired in advance.

[0032] As described above, the positional deviation detecting device 10 can detect the positional deviation B of the optical fiber 100 efficiently and quickly without requiring trial and error.

[0033] It is also possible to align the optical fiber 100 based on the positional deviation detected by the positional deviation detection device 10. Fig. 5 is a diagram showing a modification of the positional deviation detection device according to an embodiment. As shown in Fig. 5, the positional deviation detection device 10 may have a display unit 4.

[0034] The display unit 4 displays the positional deviation B calculated by the calculation unit 3 so that it can be visually recognized by a user of the positional deviation detection device 10. The display unit 4 may be configured as a display means such as a display device, for example.

[0035] The user of the positional deviation detection device 10 may adjust the position of the optical fiber 100 by, for example, operating a holding mechanism for the optical fiber 100 so that the positional deviation B displayed on the display unit 4 is equal to or less than a predetermined value. This allows the optical fiber 100 and the optical waveguide 201 of the optical circuit 200 to be aligned.

[0036] Therefore, according to this configuration, by monitoring the positional deviation B of the optical fiber 100 in real time, it is possible to realize efficient and quick alignment of the optical fiber.

[0037] Embodiment 2 As mentioned above, general misalignment detection has the drawback of only being able to detect misalignment in one direction because it is necessary to monitor the intensity of the reference light while changing the position of the optical fiber in one direction. Therefore, when aligning an optical fiber using general misalignment detection, the position must be adjusted in one direction at a time. Therefore, to align the X and Y directions, the alignment work must be performed twice, which takes a long time to complete.

[0038] In contrast to this, the positional deviation detection device according to this embodiment can simultaneously detect positional deviations in not only the X direction but also the Y direction, as will be explained below. Detection of positional deviations in two directions will be explained below.

[0039] In this embodiment, the vibrating unit 1 vibrates the optical fiber 100 in both the X and Y directions. Figure 6 is a diagram showing the relationship between the vibration direction and frequency of the optical fiber. The frequency f of the vibration in the X direction is X and the frequency of vibration in the Y direction, f Y are set to be relatively prime. As a result, as will be described later, the calculation unit 3 can detect peaks due to vibration in the X direction and peaks due to vibration in the Y direction in the frequency space separately. Hereinafter, the frequency f of vibration in the X direction will be referred to as X and the frequency of vibration in the Y direction, f Y are also referred to as the first and second frequencies, respectively.

[0040] The configuration and operation of the light receiving sections 2 and 3 are the same as those in the first embodiment, so a duplicated description will be omitted.

[0041] Next, the frequency components contained in the detection signal DET will be considered. Fig. 7 is a diagram showing an example of the detection signal and the Fourier transform result of the detection signal. The upper part of Fig. 7 shows the optical fiber 100 as X = 1 Hz in the X direction, and f Y 1 is a graph showing the time variation of the detection signal when vibrating in the Y direction at 1.5 Hz. The intensity of the detection signal DET changes periodically in accordance with the vibration of the optical fiber 100. However, since the optical fiber 100 is vibrated in two directions here, the detection signal DET shows more complex variations compared to the case of FIG.

[0042] The lower part of Figure 7 is a graph showing the Fourier transform results of the detection signal. X and frequency f Y Since the peaks due to vibration in the X direction and the peaks due to vibration in the Y direction appear at different positions in the frequency space, f X At f = 1 Hz, a peak appears, which corresponds to the product of the displacement in the X direction and the amplitude of the vibration. YA peak corresponding to the product of the positional deviation in the Y direction and the vibration amplitude appears at a frequency of 1.5 Hz, which makes it possible to separately detect the positional deviation in the X direction (also referred to as the first positional deviation) and the positional deviation in the Y direction (also referred to as the second positional deviation).

[0043] Therefore, with this configuration, it is possible to simultaneously detect positional deviations of the optical fiber in two directions that are orthogonal to each other within a plane perpendicular to the extending direction of the optical fiber.

[0044] As mentioned above, in general optical fiber alignment, it is only possible to measure misalignment in one direction in a plane perpendicular to the extension direction of the optical fiber. In contrast, with this configuration, it is possible to simultaneously detect misalignment in two directions, making it possible to detect misalignment more efficiently and quickly.

[0045] Embodiment 3 In this embodiment, an alignment device that aligns an optical fiber 100 based on a positional deviation detected by a positional deviation detection device 10 according to the first embodiment will be described.

[0046] 8 is a diagram showing a schematic configuration of an alignment device according to one embodiment. The alignment device 30 includes a positional deviation detection device 10, a drive unit 5, and a control unit 6.

[0047] The driving unit 5 can adjust the positional deviation of the optical fiber 100 by displacing the position of the optical fiber 100 in one or both of the X direction and the Y direction. The driving unit 5 may be configured to be able to adjust the position of the optical fiber 100 by, for example, a motor unit.

[0048] Furthermore, the vibration unit 1 and the drive unit 5 do not need to be provided separately, but may be configured as a drive means 7, such as a single motor unit, that can adjust the positional deviation of the optical fiber 100 and vibrate the optical fiber in one or two directions.

[0049] The control unit 6 performs feedback control on the driving unit 5 based on the positional deviation B in the X direction calculated by the calculation unit 3. That is, the control unit 6 controls the displacement of the optical fiber 100 by the driving unit 5 by providing a control signal CON, thereby making it possible to make the positional deviation B in the X direction smaller than a predetermined value.

[0050] This allows the optical fiber 100 and the optical waveguide 201 of the optical circuit 200 to be aligned.

[0051] Therefore, according to this configuration, by monitoring the positional deviation of the optical fiber 100 in real time, it is possible to realize efficient and quick alignment of the optical fiber.

[0052] Other embodiments Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0053] In the above-described embodiment, the case of coupling an optical fiber and an optical waveguide of an optical circuit has been described, but the combination of components to be optically coupled is not limited to this. The position deviation detection device and alignment device according to the above-described embodiment can also be applied to coupling any two optical components provided with an optical path or optical waveguide capable of transmitting light. For example, the position deviation detection device and alignment device according to the above-described embodiment can be used for position deviation detection and alignment when coupling various optical components of the same or different types, such as coupling optical fibers, coupling optical circuits, or coupling optical components such as lenses.

[0054] In the alignment device described in the third embodiment, similarly to the second embodiment, positional deviations in two directions may be detected and the positional deviations in the two directions may be adjusted simultaneously.

[0055] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0056] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0057] (Supplementary Note 1) A positional deviation detection device comprising: a vibration means for vibrating a first optical member, which transmits input reference light in a first direction through a first optical path and outputs the light to a second optical path provided in a second optical member for transmitting light in the first direction, in a second direction perpendicular to the first direction at a predetermined frequency; a light receiving means for outputting a detection signal indicating a detection result of the reference light input through the second optical path of the second optical member; and a calculation means for calculating a positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the predetermined frequency component of the detection signal.

[0058] (Supplementary Note 2) The positional deviation detection device according to Supplementary Note 1, wherein the calculation means calculates the positional deviation based on the intensity of a peak that appears at the predetermined frequency when the detection signal is Fourier transformed.

[0059] (Supplementary Note 3) The position deviation detection device according to Supplementary Note 1 or 2, wherein the vibration means vibrates the first optical element in the second direction at a first frequency and in a third direction perpendicular to the first and second directions at a second frequency different from the first frequency, and the calculation means calculates a first position deviation in the second direction according to the intensity of the first frequency component of the detection signal, and calculates a second position deviation in the third direction according to the intensity of the second frequency component of the detection signal.

[0060] (Supplementary Note 4) The position deviation detection device according to Supplementary Note 3, wherein the calculation means calculates the first position deviation based on the intensity of a peak that appears at the first frequency when the detection signal is Fourier transformed, and the calculation means calculates the second position deviation based on the intensity of a peak that appears at the second frequency when the detection signal is Fourier transformed.

[0061] (Supplementary Note 5) The position shift detection device according to Supplementary Note 3 or 4, wherein the first frequency and the second frequency are relatively prime values.

[0062] (Supplementary Note 6) The positional deviation detection device according to any one of Supplementary Notes 1 to 5, further comprising a display means for visually displaying the calculated positional deviation.

[0063] (Appendix 7) An alignment device further comprising: a positional deviation detection device according to any one of Appendices 1 to 6; a driving means capable of adjusting the positional deviation of the first optical element in the second direction; and a control means for controlling the driving means based on the calculated positional deviation in the second direction so that the positional deviation in the second direction falls within a predetermined range.

[0064] (Appendix 8) The alignment device described in Appendix 7, wherein the vibration means and the driving means are configured as a single driving means that vibrates the optical element in the second direction and is capable of adjusting the positional deviation of the optical element in the second direction.

[0065] (Supplementary Note 9) A positional deviation detection method comprising: transmitting an input reference light in a first direction through a first optical path, outputting the light to a second optical path provided in a second optical member that transmits light in the first direction, vibrating the first optical member in a second direction perpendicular to the first direction at a predetermined frequency, detecting the reference light input through the second optical path of the second optical member, outputting a detection signal indicating the detection result, and calculating a positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the predetermined frequency component of the detection signal. [Explanation of symbols]

[0066] 1. Vibration unit 2 Light receiving section 3 Arithmetic section 4 Display 5 Drive unit 6 Control Unit 7. Driving means 10, 30 Position deviation detection device 30 Position deviation detection device 100, 300 optical fiber 200 Optical circuit 201 Optical waveguide CON control signal

Claims

1. a vibration means for vibrating a first optical member, which transmits the input reference light in a first direction through a first optical path and outputs the light to a second optical path provided in a second optical member for transmitting light in the first direction, in a second direction perpendicular to the first direction at a predetermined frequency; a light receiving means for outputting a detection signal indicating a detection result of the reference light input via the second optical path of the second optical member; a calculation unit that calculates a positional deviation in the second direction between the first optical path and the second optical path in accordance with the intensity of the component of the predetermined frequency of the detection signal, Position deviation detection device.

2. the calculation means calculates the positional deviation based on the intensity of a peak that appears at the predetermined frequency when the detection signal is Fourier transformed. The positional deviation detection device according to claim 1 .

3. the vibration means vibrates the first optical member in the second direction at a first frequency, and vibrates the first optical member in a third direction perpendicular to the first and second directions at a second frequency different from the first frequency; the calculation means calculates a first positional deviation in the second direction according to the intensity of the first frequency component of the detection signal, and calculates a second positional deviation in the third direction according to the intensity of the second frequency component of the detection signal.

3. The positional deviation detection device according to claim 1 or 2.

4. The calculation means calculating the first positional deviation based on the intensity of a peak that appears at the first frequency when the detection signal is Fourier transformed; the calculation means calculates the second positional deviation based on the intensity of a peak that appears at the second frequency when the detection signal is Fourier transformed.

4. The positional deviation detection device according to claim 3.

5. the first frequency and the second frequency are relatively prime values; 4. The positional deviation detection device according to claim 3.

6. further comprising a display means for visually displaying the calculated positional deviation; 3. The positional deviation detection device according to claim 1 or 2.

7. a positional deviation detection device according to claim 1 or 2; a driving means capable of adjusting a positional deviation of the first optical member in the second direction; and a control unit that controls the driving unit based on the calculated positional deviation in the second direction so that the positional deviation in the second direction falls within a predetermined range. Alignment device.

8. the vibration means and the driving means are configured as a single driving means that vibrates the optical member in the second direction and is capable of adjusting a positional deviation of the optical member in the second direction. The alignment device according to claim 7.

9. a first optical member that transmits the input reference light in a first direction through a first optical path and outputs the light to a second optical path provided in a second optical member that transmits the light in the first direction, and vibrates the first optical member in a second direction perpendicular to the first direction at a predetermined frequency; detecting the reference light input via the second optical path of the second optical member, and outputting a detection signal indicating the detection result; calculating a positional deviation in the second direction between the first optical path and the second optical path according to the intensity of the component of the predetermined frequency of the detection signal; Position deviation detection method.

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