JPH0943456A - Device and method for adjusting optical axis of optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time for adjusting the optical axis of an optical module. SOLUTION: The device is provided with an XY stage 7 for mounting an LD module 1, a fiber chuck 5 for fixing the incident end of an optical fiber 3, an infrared ray image pickup tube camera 9 for observing the laser spot 8 of the LD module 1 and an image processer 10 for detecting the position of the laser spot 8 based on an image taken in by the camera 9, and the LD module 1 is moved by the XY stage 7 as long as the relative position between the position of the laser spot 8 detected by the image processor 10, the camera 9 and the incident end of the optical fiber 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module optical axis adjusting device and method, and more particularly to an optical module optical axis adjusting device and method for performing optical axis alignment between a semiconductor laser and an optical fiber.

[0002]

2. Description of the Related Art A conventional optical module optical axis adjusting method is disclosed in Japanese Patent Laid-Open No. 1-180507.

In the conventional optical axis adjusting method, as shown in FIG. 6A, the LD module 17 is fixed so that its outgoing optical axis is substantially parallel to the basic optical axis, and one end of the optical fiber (optical fiber 16 ) Is held in a state where the light receiving surface is held close to the LD module 17 on the emission optical axis of the LD module 17
While monitoring the light emitted from the D module 17 through the optical fiber with a sensor (not shown), the optical fiber 16 is moved so as to scan in two XY directions which are perpendicular to the basic optical axis and are orthogonal to each other. A surface search step for locating the optical fiber 16 so that the output of the sensor is maximized, and a two-plane plane that includes the basic optical axis and is orthogonal to each other, as shown in FIG. 6B after the surface search step. Optical fiber 16
Is rotated about the light-receiving surface to adjust the angle so that the output of the sensor is maximized to the state shown in FIG. 6 (c), and as shown in FIG. 6 (d) after this angle search step. The optical fiber 16 is moved in the direction of the basic optical axis, the surface search is performed in two directions perpendicular to the direction of the basic optical axis, and the optical fiber 16 and the LD module 17 are positioned at a position where the output of the sensor is maximized. The optical axis coarse adjustment including a focus search step for adjusting the interval is performed, and then the optical fiber 16 is further moved in the X and Y directions at intervals smaller than those in the case of the optical axis coarse adjustment to maximize the output of the sensor. The optical fiber 16 is precisely adjusted to the position.

[0004]

In the above-mentioned conventional optical axis adjusting method, it is necessary to perform a surface search for introducing the laser beam emitted from the LD module into the optical fiber before the angle search and the focus search. is there. This surface search scans the optical fiber in the XY directions over the entire range where the laser beam may be located, and finds the position of the optical fiber that maximizes the amount of light transmitted through the optical fiber. The position of the laser beam varies within a range of several tens to several hundreds of μm due to variations in mounting of the LD beret and mounting of a lens for condensing the laser beam.

On the other hand, the core diameter of the optical fiber is about 10 μm at most in the single mode, and the laser beam emitted from the LD module is 10 μm at the focus position.
The distance between the XY scans during the surface search is 10
Must be below μm. For example, 500x50
For surface search in the range of 0 μm at 10 μm intervals, 25
It is necessary to move the stage 00 times and measure the optical power.

Therefore, in the conventional optical module optical axis adjusting method, it takes a long time to perform a surface search for introducing a laser beam into the optical fiber first, and it takes a long time to adjust the optical axes of the LD module and the optical fiber. There is a drawback, and the drawback of this optical module optical axis adjusting method is that the productivity of the optical module assembly is not improved.

[0007]

SUMMARY OF THE INVENTION An optical module optical axis adjusting device of the present invention comprises an LD chuck for fixing a semiconductor laser (LD) module, and an XY equipped with the LD chuck.
Direction, a fiber chuck for fixing the entrance end of the optical fiber to a position corresponding to the LD module positioned at the optical axis alignment position by this stage, and positioned for the laser spot position measurement position by the stage And a photodetector whose position relative to the optical axis of the incident end of the optical fiber fixed to the fiber chuck is known. The photodetector processes the video signal from the imaging device, which captures an image of the laser spot and whose relative position between the optical axis and the optical axis of the incident end of the optical fiber fixed to the fiber chuck is known. An image processing device that detects the position of the laser spot with respect to the optical axis of the imaging device, or a relative of the optical axis that projects the laser spot and the optical axis of the incident end of the optical fiber fixed to the fiber chuck. A lens whose position is known,
Regarding the lens, a pinhole arranged at a position conjugate with the laser spot, and a laser beam from an LD module arranged between the lens and the pinhole at a laser spot positioning position are biaxially directed. A device provided with a laser beam scanner for deflection scanning and a laser beam detection element for measuring the intensity of the laser beam passing through the pinhole, or fixed to the center and the fiber chuck arranged on the image plane of the laser spot A cross slit having a known relative position to the optical axis of the incident end of the optical fiber, and a laser beam detection for measuring the intensity of the laser beam from the LD module positioned at the laser spot positioning position passing through the cross slit. And an element.

In the optical module optical axis adjusting method of the present invention, the position of the laser spot of the LD module fixed at the position for measuring the laser spot position is measured by a photodetector, and the position of the laser spot measured by the photodetector is measured. Then, the LD module is moved by the amount corresponding to the correction of the relative position between the photodetector and the optical axis of the incident end of the optical fiber fixed to the optical axis alignment position, and the LD module and the incident end of the optical fiber are moved. It is characterized by aligning the optical axes of. The photodetector includes an image pickup device that picks up an image of a laser spot, and an image processing device that processes a video signal from the image pickup device to detect the position of the laser spot with respect to the optical axis of the image pickup device. The LD module is moved by an amount corresponding to the position of the laser spot detected with respect to the optical axis of the imaging device added to the relative position between the optical axis of the imaging device and the optical axis of the incident end of the optical fiber. The detector has a lens for projecting a laser spot, a pinhole arranged at a position conjugate with the laser spot with respect to the lens, and an LD arranged between the lens and the pinhole and fixed at a laser spot position measuring position. A laser beam scanner that deflects and scans a laser beam from a module in two axial directions, and an intensity of the laser beam that passes through the pinhole. And a laser beam detecting device for measuring a,
The position of the laser spot with respect to the optical axis of the lens when the maximum intensity of the laser beam is measured by the laser beam detecting element during scanning by the laser beam scanner is determined by the optical axis of the lens and the incident end of the optical fiber. The LD module can be moved by the amount added to the relative position with respect to the optical axis.

According to the optical module optical axis adjusting method of the present invention, the intensity of the laser beam from the LD module passing through the cross slit arranged on the image plane of the laser spot of the LD module fixed at the laser spot position measuring position. Is measured, and the LD module is moved from a position (Xmax, Ymax) consisting of the following coordinates by a relative position of the optical axis of the incident end of the optical fiber fixed to the center of the cross slit and the optical axis alignment position. The optical axes of the LD module and the incident end of the optical fiber are aligned.

Coordinate Xmax: The maximum intensity of the laser beam passing through the cross slit when the LD module is moved below the cross slit in the direction of the X axis which is the direction of one linear slit of the cross slit. Coordinates on the X axis of the LD module when detected.

Coordinate Ymax: The maximum intensity of the laser beam passing through the cross slit when the LD module is moved below the cross slit in the direction of the Y axis which is the direction of the other linear slit of the cross slit. Coordinates on the Y-axis of the LD module when detected.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

The optical module optical axis adjusting device shown in FIG.
The LD chuck 2 that fixes the LD module 1 and the metal tube 4 that is packaged at the incident end of the optical fiber 3 are fixed so as to face the LD module 1 that is held by the LD chuck 2 at a predetermined optical axis alignment position. Fiber chuck 5 and L
The D chuck 2 is mounted and the laser beam 6 emitted from the LD module 1 can be moved in the XY plane perpendicular to the optical axis to align the optical axis of the optical fiber 3 and the optical axis of the LD module 1. An infrared imaging tube camera 9 for observing a laser spot 8 which is arranged above the XY stage 7 and the LD module 1 held at a position for measuring the position of the laser spot by the LD chuck 2 and where the laser beam 6 is condensed. And an image processing device 10 for processing the video signal output from the infrared camera tube camera 9 to detect the position of the laser spot 8 in the screen.

Next, the procedure of the optical axis adjustment according to this embodiment will be described.

The LD module 1 held by the LD chuck 2 is moved by the XY stage 7 so as to face the infrared imaging tube camera 9 and a position which faces the incident end of the optical fiber 3 fixed to the fiber chuck 5. The optical fiber 3 in the metal tube 4 fixed to the optical axis of the infrared camera 9 and the fiber chuck 5
The relative position with respect to the optical axis of is known. The optical axis of the infrared imaging tube camera 9, the optical axis of the LD module 1 and the metal tube 4
The optical axis of the inner optical fiber 3 is perpendicular to the XY plane.

Before the optical axes of the LD module 1 and the optical fiber 3 are aligned with each other, the LD module 1 is moved to a position facing the infrared camera tube camera 9 by the XY stage 7, and the laser spot 8 is imaged by the infrared camera tube camera 9. Then, the position of the image of the laser spot 8 with respect to the center of the screen is determined and
0 is detected. FIG. 2 is a screen imaged by the infrared camera tube camera 9 shown in FIG. On the screen shown in FIG. 2, only the laser spot 8 is imaged brightly, and the image processing apparatus 10 binarizes this grayscale image to calculate the center of gravity, thereby calculating the position Δx of the laser spot 8 with respect to the screen center.
Calculate Δy.

After detecting the position of the laser spot 8, image processing is performed on the relative position between the optical axis of the known infrared camera tube camera 9 and the optical axis of the optical fiber 3 in the metal tube 4 fixed to the fiber chuck 5. The XY stage 7 is moved by an amount corresponding to the position shift of the laser spot 8 detected by the apparatus 10 from the position (Δx, Δy) with respect to the screen center with respect to the optical axis of the infrared camera tube camera 9. As a result, the position of the laser spot 8 of the LD module 1 can be accurately aligned with the optical axis of the incident end of the optical fiber 3 in the metal tube 4.

Positioning errors that may occur in this case are caused by the detection error of the laser spot 10 by the image processing apparatus 10 and the positioning error of the XY stage 7. However, since the mechanical dimension error of the LD module 1 does not affect the alignment, the core diameter of the optical fiber 3 is 10
The optical axes of the LD module 1 and the incident end of the optical fiber 3 can be aligned with an accuracy of μm or less.

In the optical module generally produced for optical communication, the wavelength of the LD used for it is 1.3 to
Since the infrared ray is 1.55 μm, the infrared image pickup tube camera 9 having the sensitivity to the wavelength of the infrared ray is used in the present embodiment. However, if the wavelength of the laser beam 6 of the LD module 1 to be used has the sensitivity, it is like a CCD. Even if a camera using such a solid-state image sensor is used, the same effect as that of the above-described embodiment can be obtained.
Further, a position detection element (PSD) that detects the position of the light beam may be used instead of an image pickup element such as an image pickup tube or a CCD capable of inputting an image.

FIG. 3 is a perspective view showing another embodiment of the present invention.

The optical module optical axis adjusting device shown in FIG.
The LD chuck 2 that fixes the LD module 1 and the metal tube 4 that is sheathed at the incident end of the optical fiber 3 are attached at a predetermined position L
A fiber chuck 5 fixed so as to face the LD module 1 held by the D chuck 2;
And an XY stage 7 capable of moving the optical axis of the optical fiber 3 and the optical axis of the LD module 1 by moving in the XY plane perpendicular to the optical axis of the laser beam 6 emitted from the LD module 1. A lens 11 arranged above the LD module 1 held at a position for measuring the position of the laser beam by the LD chuck 2 and projecting a laser spot 8 formed by condensing the laser beam 6, and passing through the lens 11. The galvano mirror 1 is arranged in the optical path of the laser beam 6 and deflects and scans the laser beam 6 in two axial directions.
2, a pinhole 13 arranged at a position conjugate with the laser spot 8 with respect to the lens 11, and an infrared detection element 14 for measuring the beam intensity of the laser beam 6 that has passed through the pinhole 13. The relative position between the optical axis of the lens 11 and the optical axis of the incident end of the optical fiber 3 in the metal tube 4 is known.

In the embodiment shown in FIG. 3, the position of the laser spot 8 is projected on the surface of the pinhole 13 by the lens 11, but the image of the laser spot 8 projected on the surface of the pinhole 13 is the galvanometer mirror 12. Is scanned at high speed in the XY directions. In this scanning, the infrared detection element 1
The position of the laser spot 8 with respect to the optical axis of the lens 11 can be obtained from the position of the galvanometer mirror 12 at which the intensity of the laser beam 6 detected by 4 is maximum.
After determining the position of the laser beam 8, the LD module 1 is moved to a position facing the metal tube 4 fixed to the fiber chuck 5 by the XY stage 7 as in the embodiment shown in FIG. The metal tube 4 and the metal tube 4 are accurately aligned.

Scan the galvanometer mirror 12 and pinhole 1
Obtaining the position where the laser beam 6 passing through 3 is maximum is equivalent to a surface search in which the XY stage 7 is scanned to detect the amount of transmitted light of the optical fiber 3, but the galvano mirror 12 is Because it is very lightweight,
High-speed scanning is possible compared with the XY stage 7.

In the embodiment shown in FIG. 3, an inexpensive infrared detecting element 14 which can detect only the amount of received light is used for detecting the laser beam 6 which is an infrared ray, so that the apparatus can be constructed at low cost. .

FIG. 4 is a perspective view showing still another embodiment of the present invention.

The optical module optical axis adjusting device shown in FIG.
The LD chuck 2 that fixes the LD module 1 and the metal tube 4 that is sheathed at the incident end of the optical fiber 3 are attached at a predetermined position L
A fiber chuck 5 fixed so as to face the LD module 1 held by the D chuck 2;
And an XY stage 7 capable of moving the optical axis of the optical fiber 3 and the optical axis of the LD module 1 by moving in the XY plane perpendicular to the optical axis of the laser beam 6 emitted from the LD module 1. The laser beam 6 of the LD module 1 is arranged on the image plane of the laser spot 8 formed by converging the laser beam 6 and fixed to the fiber chuck 5, and the center and the optical axis of the incident end of the fiber 3 in the metal tube 4 are fixed. The cross slit 15 whose relative position is known is known, and the infrared detecting element 14 for measuring the beam intensity of the laser beam 6 which has passed through the cross slit 15.

The cross slit 15 shown in FIG. 4 comprises a linear slit 15a in the x-axis direction and a linear slit 15b in the y-axis direction which intersect each other. 5A and 5B show the intensity of the laser beam 6 passing through the cross slit 15 when the LD module 1 is moved below the cross slit 15 in the X direction and the Y direction by the XY stage 7. It is a graph. FIG. 5 (a)
Shows a change in the light quantity of the laser beam 6 that has passed through the slit 15b when the LD module 1 is moved in the X-axis direction by the XY stage 7. FIG. 5B shows the LD module 1 being moved by the XY stage 7 in the Y-axis direction. The change in the light amount of the laser beam 6 that has passed through the slit 15a when moved in the direction is shown. The X-coordinate and the Y-coordinate when the amount of light becomes maximum are respectively defined as Xmax and Ymax.

Next, the procedure of adjusting the optical axis in this embodiment will be described.

5A and 5B, the XY stage 7 is moved to a position where the LD module 1 faces the cross slit 15, and the LD module 1 is moved once in the X-axis direction and once in the Y-axis direction. ) Cross slit 1 as shown in
The data of the light quantity change of the laser beam 6 passing through 5 is taken. L is set to the position (Xmax, Ymax) where the light intensity is maximum.
The D module 1 is moved, that is, the laser spot 8
Is aligned with the center of the cross slit 15, and then the XY stage 7 is moved by the relative position between the known center of the cross slit 15 and the optical axis of the optical fiber 3 in the metal tube 4 fixed to the fiber chuck 5.

By accurately aligning the laser spot 8 with the center of the cross slit 15 whose distance from the optical fiber 3 is known in advance, the optical fiber 3 fixed to the fiber chuck 5 is aligned. The laser spot 8 can be accurately aligned.

In this embodiment, an expensive image pickup tube having infrared sensitivity, an infrared image pickup device such as a CCD, and a galvanometer mirror 12 for scanning the laser beam 6 are not required.
The device can be configured at low cost. Further, in order to detect the position of the laser spot 8, the L by the XY stage 7 is detected.
The D module 1 needs to be moved, but the search time can be very short because it only needs to be performed once in the XY directions.

[0033]

The optical module optical axis adjusting device and method according to the present invention is provided with an L fixed to a laser spot position measuring position.
A relative position in which the position of the laser spot of the D module is detected by the photodetector, and the relative position between the optical axis of the incident end of the optical fiber fixed at the position for optical axis alignment and the photodetector is corrected at the detected position. By moving the LD module by an amount, the optical axes of the optical fiber and the LD module can be adjusted in a short time, and the productivity of the optical module can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a screen imaged by an infrared ray imaging tube camera 9 shown in FIG.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing still another embodiment of the present invention.

FIG. 5 is a graph showing a signal obtained by the infrared detection element shown in FIG.

FIG. 6 is a perspective view showing a conventional optical axis adjusting method.

[Explanation of symbols]

 1,17 LD module 2 LD chuck 3,16 Optical fiber 5 Fiber chuck 7 XY stage 9 Infrared imaging tube camera 10 Image processing device 12 Galvano mirror 13 Pinhole 14 Infrared detection element 15 Cross slit.

Claims (8)

[Claims] 1. An LD chuck for fixing a semiconductor laser (LD) module, and an XY in which the LD chuck is mounted.
Direction, a fiber chuck for fixing the entrance end of the optical fiber to a position corresponding to the LD module positioned at the optical axis alignment position by this stage, and a laser spot position measurement position by the stage And a photodetector whose relative position to the optical axis of the incident end of the optical fiber fixed to the fiber chuck is known. Axis adjustment device. 2. A photodetector, which picks up an image of a laser spot and has a known relative position between an optical axis and an optical axis of an incident end of an optical fiber fixed to a fiber chuck, and a video from the imaging apparatus. The optical module optical axis adjusting device according to claim 1, further comprising: an image processing device that processes a signal to detect a position of the laser spot with respect to the optical axis of the imaging device. 3. A photodetector, which projects a laser spot, has a known relative position between the optical axis and the optical axis of the incident end of the optical fiber fixed to the fiber chuck, and the laser spot with respect to the lens. A pinhole arranged at a conjugate position, and an LD arranged between the lens and the pinhole and positioned at a laser spot positioning position
2. A laser beam scanner for deflecting and scanning a laser beam from a module in two axial directions, and a laser beam detecting element for measuring the intensity of the laser beam passing through the pinhole. Optical module optical axis adjustment device. 4. The photodetector comprises a cross slit having a known relative position between the center of the laser spot and the optical axis of the incident end of the optical fiber fixed to the fiber chuck, and the cross slit. The optical module optical axis adjusting device according to claim 1, further comprising a laser beam detecting element that measures the intensity of the laser beam from the LD module positioned at the laser spot positioning position that has passed through the slit. 5. The position of the laser spot of the LD module fixed to the position for measuring the laser spot position is measured by a photodetector, and the optical axis is aligned with the photodetector at the position of the laser spot measured by this photodetector. The LD module is moved by an amount corresponding to the correction of the relative position with respect to the optical axis of the incident end of the optical fiber fixed to the use position, and the optical axes of the LD module and the incident end of the optical fiber are aligned. Optical module optical axis adjustment method. 6. The photodetector comprises an image pickup device for picking up an image of a laser spot, and an image processing device for processing a video signal from the image pickup device to detect the position of the laser spot with respect to the optical axis of the image pickup device. Moving the LD module by the amount of the position of the laser spot detected by the photodetector with respect to the optical axis of the imaging device added to the relative position between the optical axis of the imaging device and the optical axis of the incident end of the optical fiber. The optical module optical axis adjusting method according to claim 5, wherein. 7. A photodetector is a lens for projecting a laser spot, a pinhole arranged at a position conjugate with the laser spot with respect to the lens, and a laser spot position measurement arranged between the lens and the pinhole. The laser beam includes a laser beam scanner that deflects and scans a laser beam from an LD module fixed in a use position in two axial directions, and a laser beam detection element that measures the intensity of the laser beam passing through the pinhole. The position of the laser spot with respect to the optical axis of the lens when the detection element measures the maximum intensity of the laser beam during the scanning by the laser beam scanner is the optical axis of the lens and the optical axis of the incident end of the optical fiber. 6. The optical axis of the optical module according to claim 5, wherein the LD module is moved by an amount added to the relative position with respect to Settling method. 8. The intensity of the laser beam from the LD module passing through a cross slit arranged on the image plane of the laser spot of the LD module fixed at the laser spot position measuring position is measured, and the LD module is measured as follows. From the position (Xmax, Ymax) consisting of the coordinates of X, the relative position of the optical axis of the entrance end of the optical fiber fixed to the center of the cross slit and the optical axis alignment position is moved to the L position.
An optical module optical axis adjusting method, characterized in that the optical axes of the D module and the incident end of the optical fiber are aligned. Coordinate Xmax: When the maximum intensity of the laser beam passing through the cross slit is detected when the LD module is moved below the cross slit in the direction of the X axis which is the direction of one linear slit of the cross slit. Of the LD module on the X-axis. Coordinate Ymax: When the maximum intensity of the laser beam passing through the cross slit is detected when the LD module is moved below the cross slit in the direction of the Y axis which is the direction of the other linear slit of the cross slit. Coordinates of the LD module on the Y axis.