JP6006681B2 - Optical device optical axis adjusting device and optical axis adjusting method - Google Patents

Description

  The present invention relates to an optical axis adjusting apparatus and an optical axis adjusting method for an optical device, and more particularly, to connecting various optical devices, for example, between optical fibers or between optical fibers and optical waveguides. The optical axis adjustment of the optical device, which automatically performs coarse adjustment so that the transmitted light intensity transmitted through the connection can be detected as a pre-process for precise optical axis adjustment by monitoring the transmitted light intensity transmitted. The present invention relates to an apparatus and an optical axis adjustment method.

  Many optical components such as optical fibers, optical waveguides, and semiconductor lasers are connected in an optical transmission line of an apparatus or system used for optical communication, optical measurement, and the like, and they need to be positioned and connected in a micron order. For this reason, speeding up, high efficiency, and labor saving of the connection work between the optical components are important issues.

  In order to ensure the final optical characteristics in the optical device mounting / assembly process that forms an optical module by assembling multiple optical devices, such as connecting and assembling optical fibers and connecting and assembling optical fibers and optical waveguides. In addition, an optical axis adjustment step for adjusting the light propagating through the core portion to take the maximum value is necessary. In order to perform such optical axis adjustment, information on the transmitted light intensity is indispensable, and the optical axis of the optical component to be connected in advance is obtained so that a detectable level of transmitted light intensity can be obtained to start the optical axis adjustment. Must be provisionally adjusted with an accuracy of about 10 μm. This temporary adjustment needs to be performed in a total of three axial directions: an axis parallel to the optical axis (hereinafter referred to as the Z axis) and two axes orthogonal thereto (hereinafter referred to as the X axis and Y axis). At this time, with respect to an axis parallel to the optical axis, in order to accurately grasp the contact surface contact position between the optical devices, it is one of the indispensable steps to measure the distance between the optical fibers or between the optical fiber and the end face of the optical waveguide. It has become one.

  A conventional method related to such temporary adjustment of the optical axis will be described with reference to FIG. The method of observing the emitted light at the end of the optical waveguide using a microscope is shown, and temporary adjustment is performed with respect to the X axis and the Y axis. (1) The optical fiber 2 is scanned using the 6-axis fine movement stage 6 with the light from the semiconductor laser light source 1 applied to one end face of the optical waveguide 3 on the fixed stage 7 through the optical fiber 2. (2) The light that propagates through the optical waveguide 3 and exits from the other end face of the optical waveguide 3 is observed using the microscope 4 and the CCD camera 5. By this procedure, the optical axis position at the connection point 9 is adjusted via the controller 8.

  FIG. 2 shows a method of performing temporary adjustment by temporarily using a multimode fiber 13 having a large core diameter. For example, if a multimode fiber 13 having a core diameter of about 50 μm, which is about five times as large as a single mode fiber, is used as a light receiving fiber, high accuracy positioning on the light receiving side is not required, and positioning there is not possible. It becomes easy. In FIG. 2, the light emitted from the end face of the multimode fiber 13 is observed with the optical power meter 14, and the position of the multimode fiber 13 is adjusted with the six-axis fine movement stage 15.

  In addition, regarding temporary adjustment in the Z-axis direction, conventionally, when a relatively large optical device such as a fiber array block comes into contact with the optical waveguide, a repulsive force is detected by the extension of the spring, and the distance is increased by the extension of the spring. A method of estimating and adjusting the interval (contact type method) has been adopted (see Patent Document 1).

  Further, as a means for measuring a minute distance in the Z-axis direction in a non-contact manner, there is generally a measuring method using an optical heterodyne interferometer. However, a means for detecting a phase difference is necessary, and polarization plane control is performed. It was necessary to prepare a special measurement system such as necessity, collimation of incident light on the measurement target, and use of modulated light (see Patent Document 2).

Japanese Patent No. 4111362 Japanese Patent No. 2216762

  However, in the conventional temporary adjustment method related to the XY axis for observing the emitted light at the end of the optical waveguide using the above-described microscope, a method of measuring and observing the light transmitted through the connecting portion is employed. When trying to connect the three parts of the optical waveguide and optical fiber, it is necessary to make sequential adjustments at the connection part on the input side and output side, and after the optical axis adjustment on one side is completed, the multimode fiber When a microscope or a microscope is replaced with an optical part to be connected, a positioning error of the fine movement stage always occurs, so that an extra adjustment process is necessary to eliminate the error, and the total number of processes is large. Thus, there is a problem that the work time becomes enormous.

  Furthermore, regarding the Z-axis temporary adjustment method, the contact type method described above cannot be detected unless the repulsive force is large to some extent. Therefore, as in the case of the optical fiber array block, it can be applied to a component in which the periphery of the optical device is protected by a structural member. However, when applied to a single-core fiber, the force is concentrated on one point. As a result, the fiber or waveguide is damaged. Therefore, the application target of the contact-type method is limited.

  On the other hand, in the measurement method using an optical heterodyne interferometer, which is a non-contact measurement, it is necessary to have a means for detecting the phase difference, to control the polarization plane, and to collimate the incident light on the measurement target. It is necessary to use modulated light. Therefore, the measuring device itself becomes large, and there are problems that the optical axis adjusting device becomes large and is very expensive to be incorporated in the optical axis adjusting device.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to increase the efficiency of the optical axis temporary adjustment work by parallel processing of the temporary adjustment of a plurality of connecting portions, and to provide an inexpensive and highly reliable system. The object is to realize an optical axis adjusting device.

  In order to solve the above-described problem, the invention described in one embodiment includes a first optical device having an end surface that reflects part of incident light from a light source and emits part of the light, and the first optical device. The relative position between the second optical device having an end face that reflects a part of the light emitted from the optical device to the first optical device, and the second optical device and the first optical device is changed. A fine movement stage that moves in such a manner, a reflected light receiver that measures the light intensity of the return light in the incident light direction of the first optical device, an intensity variation of the return light in the reflected light receiver, and the fine movement stage A reflected light signal processing unit that associates the amount of movement, an optical axis adjustment control unit that calculates the amount of movement of the fine movement stage necessary to reach the target position based on the correspondence between the intensity variation and the amount of movement, Necessary to reach the target position An optical axis adjusting device for an optical device characterized by comprising a fine movement stage control unit for moving the fine movement stage movement amount set as the dynamic quantity.

  The invention described in another embodiment includes a first optical device having an end face that reflects part of incident light from a light source and emits part of the light, and light emitted from the first optical device. A second optical device having an end face that partially reflects the first optical device; a fine movement stage that moves so as to change a relative position between the second optical device and the first optical device; A reflected light receiver that measures the light intensity of the return light in the incident light direction of the first optical device, and reflected light that correlates the intensity fluctuation of the return light in the reflected light receiver and the amount of movement of the fine movement stage. Necessary to obtain the target position, a signal processing unit, an optical axis adjustment control unit that calculates the amount of movement of the fine movement stage necessary to reach the target position based on the correspondence between the intensity fluctuation and the movement amount Movement amount set as a safe movement amount An optical axis adjustment method in an optical axis adjustment apparatus comprising a fine movement stage control unit for moving the fine movement stage, wherein the fine movement stage is moved while incident light is incident on the first optical device; The step of storing the movement amount of the fine movement stage and the light intensity of the return light, and the step of calculating the movement amount of the fine movement stage necessary to reach the target position based on the stored movement amount and light intensity. And a step of moving the fine movement stage by the calculated amount of movement by the fine movement stage control unit.

In the present invention, even when there are a plurality of connecting portions (locations where light adjustment is performed), the optical axes can be adjusted simultaneously, and the adjustment time can be reduced.

It is a figure which shows an example of the conventional optical axis rough adjustment apparatus. It is a figure which shows another example of the conventional optical axis rough adjustment apparatus. It is a figure which shows the optical axis adjustment apparatus in 1st Embodiment. It is a figure which shows the optical axis adjustment process flow in 1st Embodiment. It is a figure explaining the optical axis temporary adjustment principle in 1st Embodiment. It is a figure which shows the optical axis adjustment apparatus in 2nd Embodiment. It is a figure which shows the optical axis adjustment process flow in 2nd Embodiment. It is a figure explaining the optical axis temporary adjustment principle in 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 3 is a diagram illustrating the optical axis adjusting apparatus according to the first embodiment. In the present specification, the direction in which the optical components approach each other is referred to as the optical axis direction, which is referred to as the Z-axis direction. In this embodiment, optical axis temporary adjustment is performed in the XY direction that is perpendicular to the Z-axis direction. The optical axis adjusting device includes a light source 20, an optical fiber 21, an optical fiber 22, a fine movement stage 23, a fine movement stage 24, a reflected light receiver 25, a reflected light signal processing unit 26, and a fine movement stage control unit 27. And an optical axis adjustment control unit 28 and a 1 × 2 coupler 29.

  FIG. 4 is a diagram showing an optical axis temporary adjustment flow. After starting the optical axis temporary adjustment, the light incident on the optical fiber 21 from the light source 20 is emitted from the one end face side of the optical fiber 21 into the air (S1). The light emitted into the air is reflected by the end face of the optical fiber 22 and again enters the reflected light receiver 25 through the core portion from the end face of the optical fiber 21. Using the fine movement stage control unit 27, the optical fiber 21 is moved by the fine movement stage 23 for each set step amount in the XY direction within the setting range (S2). The reflected light signal processing unit 26 records the relationship between the set amount of movement of the fine movement stage 23 and the light intensity obtained by the reflected light receiver 25 in a storage unit (not shown) (S3). Based on the relationship between the recorded movement amount and the light intensity, the optical axis adjustment control unit 28 on which the optical axis temporary adjustment method to be described later is mounted specifies the core position and the movement amount necessary to become the target position. Is calculated (S4). The fine movement stage controller 27 sets the fine movement stage 23 to the calculated movement amount and moves it to the target position (S5). In this way, the optical axis temporary adjustment in the XY axis directions is completed (S6).

FIG. 5 is a diagram illustrating the principle of optical axis temporary adjustment in the XY-axis direction in connection between optical fibers. Since the core part 31 and the clad part 32 of the optical fiber A30 and the core part 34 and the clad part 35 of the optical fiber B33 have different refractive indexes, light is guided through the core part. For materials having different refractive indexes, the reflectance also varies depending on the refractive index. When light propagated in the air enters the material, assuming that the refractive index of air is 1 and the refractive index of the material is n, the reflectance R of the portion is expressed by the following formula (1).
R = {(1-n) / (1 + n)} ² ... Formula (1)

  Here, calculation is performed by including values of general optical fibers. When the end face of the optical fiber B33 is a reflection surface, the refractive index of the core part 34 of the optical fiber B33 is n1 = 1.470, and the refractive index of the cladding part 35 is n2 = 1.458. 0.036, the reflectivity R2 of the clad portion 35 is 0.033. Therefore, the position of the core part 34 and the clad part 35 can be specified by detecting the optical signal intensity difference due to the reflectance difference. The optical axis adjustment control unit 28 can specify the core position based on the movement amount of the fine movement stage and the optical signal intensity difference stored in the storage unit.

  If the input light intensity from the light source is 0.1 mW, in this case, the reflected light intensity at the core part 34 is 7.2 μW considering that there are two reflecting surfaces, and the reflected light intensity at the cladding part 35 Is 6.6 μm. If the light returning to the reflected light receiving unit is halved by the 1 × 2 coupler, it is sufficient to detect a difference of 0.3 μW, which is a value that can be sufficiently identified by a commercially available optical power meter.

  In the optical axis temporary adjustment process flow shown in FIG. 4, the core position is specified by the optical axis adjustment control unit 28 in S4 based on the principle described above, and the reflected return light intensity at the core unit by the fine movement stage control unit 27 in S5. Therefore, it is only necessary to move the fine movement stages 23 and 24 to the fine movement stage setting position corresponding to.

  In the present embodiment, an example of the optical axis temporary adjustment of the two optical fiber components is shown, but the optical axis temporary adjustment of the two connection points between the three optical fiber components also uses only the information of the reflected return light, and the transmitted light Since no information is required, it can be executed independently.

  In the present embodiment, the optical axis temporary adjustment has been described using an example of a general optical fiber. Similarly, if the optical device has a different refractive index between the core and the clad, such as a quartz optical waveguide and an organic optical waveguide. Applicable. Further, if the optical device has a larger refractive index difference, the difference in the intensity of the reflected return light is large, so that detection becomes easier. Moreover, although the example which moves the optical fiber 21 with the fine movement stage 23 was shown, the optical fiber 21 may be fixed and the optical fiber 22 and the fine movement stage 24 may be moved.

(Second Embodiment)
FIG. 6 is a diagram illustrating a configuration of the optical axis adjusting apparatus according to the second embodiment. In this embodiment, optical axis temporary adjustment is performed in the Z-axis direction parallel to the optical axis. The optical axis adjusting device includes a light source 40, an optical fiber 41, an optical fiber 42, a fine movement stage 43, a fine movement stage 44, a reflected light receiver 45, a reflected light signal processing unit 46, and a fine movement stage control unit 47. And an optical axis adjustment control unit 48 and a 1 × 2 coupler 49.

  FIG. 7 is a diagram showing an optical axis temporary adjustment flow in the Z-axis direction parallel to the optical axis. After the optical axis temporary adjustment is started, incident light from the light source 40 enters from one end face side of the optical fiber 41, and light is emitted from the other end face of the optical fiber 41 into the air (S11). The light emitted into the air is reflected by the end face of the optical fiber 42, and again enters the reflected light receiver 45 from the end face of the optical fiber 41 through the core portion. Using the fine movement stage controller 47, the optical fiber 42 is moved by the fine movement stage 44 in a direction approaching the optical fiber 21 in the Z-axis direction (S2). At this time, the reflected light signal processing unit 26 records the relationship between the amount of movement of the fine movement stage 44 and the light intensity obtained by the reflected light receiving unit in a storage unit (not shown) (S13). Based on the recorded movement amount and light intensity, the movement amount necessary for achieving the target distance between the end faces is calculated by the optical axis adjustment control unit 48 in which the optical axis temporary adjustment method described later is mounted (S14). ). The fine movement stage controller 47 moves the fine movement stage 44 to a set position that is the target end-to-end distance (S15). In this way, the optical axis temporary adjustment in the Z-axis direction is completed (S16).

  FIG. 8 shows the principle of temporary adjustment of the optical axis in the Z-axis direction in the second embodiment. In this example, the optical fiber 50 and the optical fiber 51 are used. When the optical fiber 50 is close to connect to the optical fiber 51, the distance is usually shorter than the coherence distance of the incident light, so the end face of the optical fiber and the end face of the optical waveguide are so-called Fabry-Perot. It will constitute an etalon. The Fabry-Perot interference has a maximum light intensity amplitude when the distance between the reflection end faces is an integral multiple of a half wavelength. For example, in the case of the wavelength λ, h = mλ / 2 (m is an integer) is a condition. Here, h is the distance between the end faces. Using this phenomenon, the optical axis is temporarily adjusted between the optical fiber end faces.

  When the wavelength of the light source is 1.55 μm, the amplitude is maximized at intervals of an integral multiple of the half wavelength of 0.725 μm. A Z-axis interval is temporarily set based on the mechanical origin of the fine movement stage so that the distance between the optical fiber 50 and the optical fiber 51 is about 50 μm, and the optical fiber 51 is connected to the optical fiber 50 from this distance. By moving the fine movement stage closer and counting the number of light intensity amplitudes at that time by the optical axis adjustment controller 48 55 times, the Z axis interval can be temporarily adjusted to about 10 μm. it can.

  In this embodiment, an example of the optical axis temporary adjustment of the two optical fiber components has been shown. However, the optical axis temporary adjustment of the two connection points between the three optical fiber components also uses only the information of the reflected return light, and transmits the light. Since optical information is not required, it can be executed independently.

  In this embodiment, the optical axis temporary adjustment between the optical fibers has been described as an example, but the present invention can be similarly applied even when one of the optical fibers is an optical waveguide. Furthermore, although the example in which the optical fiber 42 is moved by the fine movement stage 44 has been shown, the optical fiber 42 may be fixed and the optical fiber 41 and the fine movement stage 43 may be moved.

  According to the optical axis adjusting apparatus of the present embodiment, the optical axes can be temporarily adjusted in a plurality of connection portions in parallel. For example, in the connection of three parts of an optical fiber, an optical waveguide, and an optical fiber, adjustment time is required. Compared to the conventional case, even if the number of connecting portions is increased, the adjustment can be performed at the same time, so that a remarkable effect such as reduction of the adjustment time can be obtained.

  Furthermore, with regard to the optical axis temporary adjustment in the Z-axis direction between optical devices, it is possible to measure the distance between the end faces without contact when mounting and assembling, thus preventing damage to the optical device and making the measurement more efficient In addition, the production yield can be improved and the cost can be reduced.

  The fine movement stages 43 and 44 of the second embodiment can be adjusted in the three-axis directions by using fine movement stages that can move not only in the Z-axis direction but also in the XY-axis direction.

DESCRIPTION OF SYMBOLS 20 Light source 21 Optical fiber 22 Optical fiber 23 Fine movement stage 24 Fine movement stage 25 Reflected light receiver 26 Reflected light signal processing part 27 Fine movement stage control part 28 Optical axis adjustment control part 29 1 * 2 coupler 40 Light source 41 Optical fiber 42 Optical fiber 43 Fine movement stage 44 Fine movement stage 45 Reflected light receiver 46 Reflected light signal processing section 47 Fine movement stage control section 48 Optical axis adjustment control section 49 1 × 2 coupler

Claims (2)

A first optical device having an emission end face that reflects part of incident light from the light source and emits part of the light;
A second optical device having a reflective end surface for reflecting a part of the light emitted from the first optical device to the first optical device;
A fine movement stage you move to vary along parallel axial relative position between the second optical device and the first optical device to the optical axis,
A reflected light receiver for measuring the light intensity of the return light in the incident light direction of the first optical device;
And the reflected light signal processing unit corresponding with storing the movement amount of the return light of the light intensity and the fine stage in the reflected light receiving device,
An optical axis adjustment control unit that calculates the amount of movement of the fine movement stage necessary to reach the target position based on the correspondence between the intensity fluctuation of the return light and the amount of movement;
A fine movement stage control unit that moves the fine movement stage by a movement amount set as a movement amount necessary to reach the target position ;
The light source impinges incident light on the first optical device;
The fine movement stage changes a distance between the emission end face of the first optical device and the reflection end face of the second optical device;
The optical axis adjustment control unit, based on the light intensity and the movement amount stored in the reflected light signal processing unit, the emission end face of the first optical device and the reflection of the second optical device. The emission end face of the first optical device and the second light intensity are calculated based on the number of times the light intensity becomes maximum in the intensity fluctuation of the return light caused by the interference of the Fabry-Perot etalon composed of the end face and the wavelength of the incident light. An optical axis adjustment apparatus for an optical device, characterized in that a distance between the optical device and the reflection end face is specified, and a movement amount of the fine movement stage necessary to reach the target position is calculated . A first optical device having an emission end face that reflects a part of incident light from the light source and emits a part thereof, and a part of the light emitted from the first optical device to the first optical device second and an optical device, the second light device and the first mobile to that fine movement stage so as to vary along the axial direction parallel to the optical axis of the relative position of the optical device having a reflective facet that reflects When the reflected light receiving device for measuring the light intensity of the return light to the incident light direction of the first optical device, the light intensity of the return light in the reflected light receiving device and a moving amount of the fine stage corresponding A reflected light signal processing unit for storing information, an optical axis adjustment control unit for calculating the amount of movement of the fine movement stage necessary to reach the target position based on the correspondence between the intensity variation of the return light and the amount of movement; , And the amount of movement necessary to reach the target position An optical axis adjusting method of the optical axis adjusting apparatus that includes a fine movement stage control unit for moving the fine movement stage movement amount set Te,
The light source impinges incident light on the first optical device ;
The fine movement stage changing a distance between the emission end face of the first optical device and the reflection end face of the second optical device ;
The optical axis adjustment control unit, on the basis of the stored the light intensity and the amount of movement to said reflected light signal processing unit, the reflection of the first of the exit end face and said second optical device of the optical device The emission end face of the first optical device and the second light intensity are calculated based on the number of times the light intensity becomes maximum in the intensity fluctuation of the return light caused by the interference of the Fabry-Perot etalon composed of the end face and the wavelength of the incident light. Specifying the distance between the reflection end face of the optical device and calculating the amount of movement of the fine movement stage necessary to reach the target position ;
An optical axis adjustment method comprising:

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