JP2010232370A - Lens, semiconductor laser module, and method of manufacturing optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens, a semiconductor laser module and a method of manufacturing an optical device which are capable of reducing optical axis misalignment. <P>SOLUTION: The lens 1 has a plurality of installation surfaces SA1 to SA4, and is a quadrangular prism which is different in distance between the respective installation surfaces SA1 to SA4 and an optical axis C. Normals of the installation surfaces SA1 to SA4 are perpendicular to the optical axis C, and the surfaces SA1 to SA4 form side faces of the quadrangular prism. A difference between a maximum distance and minimum distance among the distances between the installation surfaces SA1 to SA4 and optical axis C is equal to or larger than a tolerance between an installation surface SB where the lens 1 is to be installed and the lens 1. The lens 1 is fixed to an installation surface, selected so that the lens and the installed surface SB of a carrier 10 is at the minimum distance Dmin, using resin 13 for adhesion. At this time, the optical axis C of the lens 1 is aligned with an optical axis of a semiconductor laser element 12 with the consideration of a shrinkage amount of the resin 13 for adhesion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens that can be arranged with a small optical axis shift, a semiconductor laser module using the lens, and an optical device manufacturing method using the lens.

  As shown in Patent Document 1, a semiconductor laser module includes a semiconductor laser element, a condensing lens, a photodetector that monitors output light, a temperature control element such as a Peltier element, and many components such as an isolator. . In this semiconductor laser module, light emitted from a semiconductor laser element is converted into parallel light via a collimator lens, and then guided to an optical fiber via an optical isolator, and guided in the optical fiber for a desired use. Yes.

  Here, in the semiconductor laser module, an optical path from the semiconductor laser element to the optical fiber is formed by many components, and an optical member such as a lens is used. When installing a lens, it is necessary to make the optical center of the lens coincide with the optical axis of the optical path. If a deviation occurs between the optical center of the lens and the optical axis of the optical path, for example, the light emitted from the collimating lens This causes a problem that the light coupling efficiency is reduced due to a part of the light.

JP 2006-216695 A

  As described above, in the semiconductor laser module, the laser light emitted from the semiconductor laser element described above is condensed in the vicinity by the condenser lens or converted into parallel light by the collimator lens. And when installing lenses, such as this condensing lens and a collimating lens, this lens is fixed, after aligning an optical axis using adhesive resin between installation surfaces. Here, the height from the base of the module to the exit of the semiconductor laser element has a tolerance due to manufacturing variations. Conventionally, this tolerance has been eliminated by inserting an adhesive resin between the lens and the adherend surface of the base and adjusting the amount (thickness).

  However, the deviation from the design value when producing each member is large with respect to the axial deviation between the optical elements used in the semiconductor module, and accordingly, the lens mounting surface and the adherend surface of the base The amount of adhesive resin interposed therebetween also increases. Here, when the shrinkage rate at the time of fixing of the adhesive resin is constant, the optical axis of the optical system may be aligned in consideration of the shrinkage amount of the adhesive resin. When many are used, problems occur in terms of aging and strength of the material. In addition, the shrinkage rate of the actual resin has a variation in molecular weight because the adhesive resin is a polymer, the shrinkage rate is not constant, and the larger the amount of the adhesive resin, the more local the adhesive resin becomes. There is a problem in that the amount of shrinkage varies and the optical axis of the lens shifts.

  Accordingly, the present invention has been made in view of the above, and it is possible to reduce the amount of adhesive resin and to reduce the optical axis deviation caused by the shrinkage of the resin. An object of the present invention is to provide a member, a semiconductor laser module, and an optical device manufacturing method.

  In order to solve the above-described problems and achieve the object, an optical module according to the present invention includes first and second optical members and a base, and the first optical member has a first base or a first base. Mounted on the base, and the second optical member is mounted on the base directly or via a second base, and light is transmitted between the first optical member and the second optical member. In the optical module in which transmission / reception is performed, at least one of the first optical member, the first base, the base, the second optical member, or the second base compensates for a manufacturing tolerance. It has the means.

  The optical module according to the present invention is characterized in that, in the above invention, the first optical member is a lens and the second optical member is a semiconductor laser.

  In the optical module according to the present invention, in the above invention, the lens is a polygon having a plurality of installation surfaces around the lens, and the compensation means has at least two different distances from the optical center of the lens to the installation surface. Two installation surfaces, characterized in that the installation surface is selected to compensate for tolerances.

  Further, in the optical module according to the present invention, in the above invention, the first base or the second base is a rectangular parallelepiped, and the compensation means is a short side and a long side of the rectangular parallelepiped. The installation surface is selected from a short side and a long side in order to compensate for the tolerance.

  The optical module according to the present invention is the optical module according to the above invention, wherein the first base or the second base is a stepped base, and the compensation means is a step, which is optimal for compensating for tolerances. The step is selected as an installation surface of the first optical member or the second optical member.

  The lens member according to the present invention has a plurality of installation surfaces, and at least one distance between each installation surface and the optical center is different.

  In the lens member according to the present invention, in the above invention, normals of the plurality of installation surfaces are perpendicular to an optical axis of the lens, and the plurality of installation surfaces form a side surface of a polygonal column. It is characterized by.

  The lens member according to the present invention is characterized in that, in the above invention, the distance between each installation surface and the center of the optical axis is increased stepwise around the optical axis.

  The lens member according to the present invention is characterized in that, in the above invention, the plurality of installation surfaces have installation surfaces parallel to one installation surface.

  The lens member according to the present invention is characterized in that, in the above invention, the plurality of installation surfaces have a pair of installation surfaces perpendicular to one installation surface.

  The lens member according to the present invention is characterized in that, in the above-described invention, the lens member has an identification portion for identifying a predetermined installation surface.

  The optical module or lens member according to the present invention is characterized in that, in the above invention, the surface roughness Ra of at least one surface of the installation surface is 50 μm or more.

  According to the present invention, the optical element, the base, or the base has means for compensating for the tolerance, and in particular, the lens has a plurality of installation surfaces, and the distance between each installation surface and the optical center is different. The tolerance caused by the manufacturing error between the optical axis of the optical system and the optical center of the lens when installing the lens is reduced by adjusting the optimum installation surface, and the effect of this reduced tolerance is It absorbs with a small amount of adhesive resin compared with the case where there is no adjustment. As a result, the variation in the shrinkage amount of the adhesive resin is reduced, and as a result, the optical axis shift due to the shrinkage of the resin when the resin is cured after the alignment of the optical axis can be reduced. Further, there is no need to provide a new member for tolerance compensation, which is advantageous in terms of cost.

Briefly explaining the gist of the present invention, the height from the installation surface SB to the exit of the semiconductor laser element 12 is essentially the height from the optical center of the lens to the installation surface SA and the thickness of the adjustment resin. It was compensated. However, in an actual device, there has been a deviation from the design value due to tolerance. And when tolerance came out, it was adjusted by adjusting the thickness of the resin layer for adjustment. However, since the front / rear / left / right adjustment is also performed by the resin, the resin layer has a minimum required thickness (however, it is not considered when the front / rear / left / right adjustment is not required). Even when the height of the laser emission port is lowered due to tolerances, this minimum necessary thickness is necessary, so in the actual design, a thick adjustment resin is required in consideration of this margin. On the other hand, in the case of the present application, since the tolerance compensation member has at least two tolerance compensation installation surfaces, it can cope with both a plus tolerance and a minus tolerance. In addition, this eliminates the need to provide an adjustment resin thickness more than necessary. Furthermore, even when the resin layer has to be set to a large size, the thickness (amount) of the resin layer can be reduced by using an installation surface having a long adjustment length during installation.
Preferred embodiments of a lens, a semiconductor laser module, and an optical device manufacturing method according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

  FIG. 1 is a cross-sectional view showing a part of the configuration of a semiconductor laser module using a lens according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the lens shown in FIG. Further, FIG. 3 is a perspective view showing a configuration of the lens shown in FIG. 1 to 3, the lens 1 is a collimating lens, which forms a prism having a square cross section, and has four side surfaces as installation surfaces SA1 to SA4. The corner of the lens 1 is chamfered. The lens 1 has different distances d1 to d4 from the optical axis C to the respective installation surfaces SA1 to SA4. The distance d1 = 400 μm, the distance d2 = 410 μm, the distance d3 = 430 μm, the distance d4 = 440 μm, and the distance d1 → In order of d2 → d4 → d3, the distance is increased by 10 μm, and the distance from the distance d1 to the distance d3 differs by 30 μm. That is, the lens 1 can absorb the influence of a tolerance of 30 μm. The cross section is square, and the added value of the distances d1 and d3 and the added value of the distances d2 and d4 are both 430 μm.

  Further, the lens 1 is provided with a groove 20 parallel to the optical axis C on the installation surface SA1. This groove 20 is for identifying the installation surface SA1, and enables the positions of the installation surfaces SA1 to SA4 including the convex surface of the lens 1 to be identified. Further, as shown in FIG. 3, a mark 21 for individually identifying each installation surface SA <b> 2 to SA <b> 4 may be provided, or only the mark 21 may be provided instead of the groove 20.

The lens 1 is fixed on a carrier 10 having a step disposed in the semiconductor laser module and on an installation surface SB which is a lower surface of the step through an adhesive resin 13. As the adhesive resin, a UV curable resin, a thermosetting resin, or the like is used. Alternatively, first, positioning may be performed with a small amount of UV curable resin, and then fixing may be performed with a thermosetting resin such as an epoxy resin. On the other hand, the semiconductor laser element 12 is fixed to the installation surface SC on the carrier 10 which is the upper surface of the step through the solder 11. Here, the fixing is performed by soldering, but depending on the application, the fixing may be performed by welding with a Yag laser, bonding with an adhesive, or the like. Here, the semiconductor laser element 12 is arranged so that the exit of the laser beam is near the step of the carrier 10. The lens 1 is fixedly arranged with its height adjusted so that the optical axis C passing through the optical center of the lens coincides with the optical axis of the laser light.
With regard to the surface state on the lens 1 surface or the installation surface SB that is in contact with the adhesive resin 13, the authors commonly use the surface state of the lens or carrier material that is conventionally used in the module, and the adhesive material that is conventionally used. We conducted experiments on the adhesive strength with resin, and obtained practically sufficient adhesive strength by setting the surface roughness Ra (according to JIS B O601-1994 'surface roughness-definition and indication') to 50 μm or more for many materials. I found out that It is presumed that this is because the anchor effect has made it possible to obtain stronger bonding strength. As another surface state, an uneven structure that fits between the adhesive surface of the lens and the installation surface SB may be provided.

  When the lens 1 is fixed on the installation surface SB of the carrier 10 via the adhesive resin 13, the tolerance that is a variation from the design value of the height of the installation surface SB and the emission port of the semiconductor laser element 12 is The height h1 of the step of the carrier 10, the thickness h3 of the semiconductor laser element 12, the thickness h2 of the solder 11, and the height (distance) between the optical axis C passing through the optical center of the lens and the installation surface SA (SA4). This is a balance of each variation such as h4. Here, a case where the tolerance between the exit of the laser element 12 and the installation surface SB is +23 μm from the design value in the height direction will be described as an example. As will be described later, the installation surface where the distance between the installation surface SA of the lens 1 and the installation surface SB is minimized, for example, the installation surface SA4 in FIG. 1 is selected. The reference installation surface SA of the lens 1 is the installation surface SA1 having the smallest distance d1 among the distances from the optical axis C to each of the installation surfaces SA1 to SA4. From the reference installation surface SA1, The installation surface SA2 → SA4 → SA3 in which the distance increases sequentially is selected. Here, according to the present invention, 20 μm of the thickness due to tolerance can be absorbed by the lens portion, so that the effect of shrinkage of the adhesive resin can be suppressed. If the tolerance is +50 [mu] m or more, if the SA3 surface is selected, 30 [mu] m can be absorbed by the lens member out of the tolerance conventionally absorbed only by the resin.

  Again, as shown in FIG. 4, conventionally, when the optical axis of the lens 1 is aligned, the distance between the installation surface SA and the installation surface SB, that is, the tolerance ΔD is set to the thickness of the adhesive resin 13. However, in this embodiment, the installation surface SA (SA1 of the lens 1) is set according to the tolerance ΔD so that the distance between the installation surface SA and the installation surface SB becomes the minimum distance Dmin. To SA4), a part of the lens 1 is used as the adjustment portion L1, the thickness of the adhesive resin 13 is made as small as possible, and the optical axis deviation due to the variation in shrinkage due to the adhesion of the adhesive resin 13 is reduced. Yes.

  As shown in FIG. 5, even if the tolerance ΔD becomes the tolerance ΔD ′, the distances ΔD and ΔD ′ within 10 μm can always be obtained by selecting the installation surface corresponding to the tolerance ΔD ′. In addition, when the resin layer is thick, by selecting the SA3 surface having the maximum distance from the optical center of the lens to the installation surface, a part of the resin layer can be compensated by the tolerance compensation portion of the lens. The influence of can be avoided.

  FIG. 6 shows the relationship between the shrinkage amount of the adhesive resin and the thickness of the adhesive resin. As shown in FIG. 6, the smaller the thickness of the adhesive resin, the smaller the variation in the shrinkage amount of the adhesive resin. Therefore, if the tolerance ΔD is all absorbed by the thickness of the adhesive resin as in the prior art, the variation δD2 in the shrinkage rate of the adhesive resin is large, and the distance Dmin is the thickness of the adhesive resin within 10 μm. The variation δD1 in the shrinkage rate of the adhesive resin is reduced. As a result, when the lens 1 is aligned and fixed, the variation in the shrinkage rate of the adhesive resin can be reduced and the optical axis deviation can be reduced. it can.

  Here, with reference to FIG. 7, the procedure for manufacturing the optical device by aligning the optical axis of the lens 1 will be described. The optical device referred to here is a device having the semiconductor laser element 12 and converting and outputting the laser light emitted from the semiconductor laser element 12 as collimated light. As shown in FIG. 7A, first, a distance d20 between the installation surface SB of the carrier 10 and the optical axis surface SD of the semiconductor laser element 12 is measured using a laser displacement meter 30. That is, the laser displacement meter 30 measures the difference between the distance d10 between the laser displacement meter 30 and the installation surface SB and the distance d11 between the laser displacement meter 30 and the optical axis surface SD as a distance d20. . The distance d20 may be measured, for example, the distance d20 may be measured by acquiring an image near the step.

  Thereafter, the installation surfaces SA1 to SA4 having the shortest distances d1 to d4 shorter than the distance d20 are selected and set as the installation surface SA of the lens 1. Then, as shown in FIG. 7B, an adhesive resin 13 having a thickness such that the thickness after contraction is 10 μm or more is adhered onto the installation surface SB. At this time, the lens tilt angle measurement such as image recognition and distance measurement and the lens tilt degree measurement by aberration measurement are performed, and the optical axis is set to be normal to the lens surface, so that higher coupling efficiency can be obtained. Be able to. In addition, it can be arranged with an inclination of about 2 degrees in order to intentionally reduce the influence of the return light.

  Thereafter, as shown in FIG. 7 (c), the optical axis of the lens 1 with the installation surface SA of the selected lens 1 directed toward the installation surface SB and the amount of contraction when the adhesive resin 13 is fixed is taken into account. Align the core and fix the lens 1. As a result, the shrinkage amount of the adhesive resin 13 can be reduced, so that the variation in the thickness of the adhesive resin 13 at the time of fixing can be reduced, and as a result, the optical axis deviation can be reduced.

  Here, it is necessary to hold the lens 1 at the time of optical axis alignment of the lens 1 shown in FIG. As shown in FIG. 8, the gripping tool 40 can be used to hold the lens 1 by vacuum suction with respect to the installation surface SA ′ opposite to the installation surface SA of the lens 1 across the optical axis C. When this gripping tool 40 is used, it is preferable to provide an installation surface SA ′ parallel to the installation surface SA. For example, it is preferable that the lens 1 has an even number of installation surfaces such as a quadrangular column and a hexagonal column.

  Further, as shown in FIG. 9, a pair of installation surfaces SA ″ perpendicular to the installation surface SA and facing the optical axis C are provided, and the lens 1 is attached to the installation surface SA ″ from the horizontal direction by the arms 41a and 41b. You may use the holding tool 40 to hold | grip. When the gripping tool 40 shown in FIG. 9 is used, it is preferable that the lens 1 has an installation surface that is a multiple of 4, such as a quadrangular prism or an octagonal prism.

  Here, a semiconductor laser module using the lens 1 described above will be described. As shown in FIG. 10, the first Peltier element 51 as the first temperature adjusting unit is disposed at the bottom of the housing 60 of the semiconductor laser module 50. Above the first Peltier element 51, a base 52 having high thermal conductivity is disposed. A second Peltier element 53 as a second temperature adjusting unit is further provided at the lower portion on one end side of the base 52. The carrier 10 having a high thermal conductivity and a step is provided on the upper part of the second Peltier element 53. As described above, the semiconductor laser element 10 is further disposed on the upper flat end of the step above the carrier 10 as described above. Is done. And the lens 1 mentioned above is arrange | positioned as a collimating lens in the to-be-installed surface which is the low part of the carrier 10. FIG. The fixing of the lens 1 on the carrier 10 with the optical axis aligned is performed by the process shown in FIG. The second Peltier element 53 mainly adjusts the temperature of the semiconductor laser element 12. On the other hand, an isolator 54 and beam splitters 55 and 56 for monitoring laser light are provided on the step upper surface of the base 52, and optical axis alignment is performed on the same plane.

  In the above-described embodiment, the lens 1 is a regular quadrangular prism. However, the present invention is not limited thereto, and may be a quadrangular prism having a rectangular cross section as shown in FIG. In this case, it can be arranged clockwise in the direction of the figure so that the distance between the optical axis C and the installation surfaces SA11 to SA12 increases step by step by 10 μm.

  Moreover, as shown in FIG. 12, an octagonal prism may be sufficient. In FIG. 12, as indicated by an arrow A1 in the drawing, the distance is increased stepwise from 400 μm by 5 μm stepwise, and finally a distance of 435 μm is obtained. In the lens shown in FIG. 12, the difference between the maximum distance and the minimum distance is set to 35 μm. Therefore, optical axis alignment can be performed up to a tolerance ΔD of 35 μm.

  It may be a regular octagonal lens. Furthermore, a triangular prism may be used. Further, the difference between the distances is the same value as 10 μm or 5 μm in the above-described example, but is not limited to this, and may be a different value.

  Next, FIG. 13 shows another embodiment of the present invention. FIG. 13 shows an example in which the lens 1 or the semiconductor laser element 12 is installed on the base 70 or the base 71 and the tolerance is compensated. The base 70 is a rectangular parallelepiped composed of a long side having a height h5 and a short side having a height h6, and the base 71 is a rectangular parallelepiped having a long side having a height h8 and a short side having a height h7. Tolerances are compensated by using the side of as a mounting surface. As a foundation for compensating for tolerance, a combination of the foundation 70 and the foundation 71 may be used. FIG. 14 shows an example in which the tolerance is compensated by the step using the base 72 having the heights h9, h10, and h11 as stepped steps as the base of the lens. Here, the base 72 is moved back and forth with respect to the optical axis to select a height to be compensated. However, the step may be set to move in a direction perpendicular to the optical axis. In the figure, the base 72 is used as the base of the lens 1, but may be used as the base of the laser 12. Finally, FIG. 15 shows an example in which a tolerance compensating rod 73 is provided below the lens 1. Here, a hole 74 having a margin w for adjusting the front and rear, left and right with respect to the optical axis of the lens 1 is provided at a position where the lens 1 of the carrier 10 is fixed, and the insertion depth of the rod 1 of the lens 1 into the hole 74 is set. Adjust the height by adjusting. In this case, since no resin is used for height adjustment, there is little change in the height direction. In the figure, the rod 73 is used as the base of the lens 1, but may be used as the base of the laser 12.

It is sectional drawing which shows a part of structure of the semiconductor laser module using the lens which is embodiment of this invention. It is a figure which shows the structure of the lens shown in FIG. It is a perspective view which shows the structure of the lens shown in FIG. It is the figure which compared the conventional lens fixation and the lens fixation of this embodiment. It is the figure which showed the relationship between the magnitude | size of tolerance and the thickness of resin for adhesion | attachment. It is a figure which shows the dispersion | variation in the shrinkage amount of the adhesive resin with respect to the thickness of adhesive resin. It is a figure which shows the manufacturing method of the optical device using the lens which is this embodiment. It is a figure which shows an example of the lens which is this embodiment, and the holding tool which hold | grips this lens. It is a figure which shows another example of the lens which is this embodiment, and the holding tool which hold | grips this lens. It is sectional drawing of the semiconductor laser module to which the lens which is this embodiment is applied. It is a figure which shows an example of the lens of a square pole whose cross section is a rectangle. It is a figure which shows an example of the lens of an octagonal prism. It is a figure which shows the other Example of this invention. It is a figure which shows the other Example of this invention. It is a figure which shows the other Example of this invention.

DESCRIPTION OF SYMBOLS 1 Lens 10 Carrier 11 Solder 12 Semiconductor laser element 13 Adhesive resin 20 Groove 21 Mark 40 Holding tool 50 Semiconductor laser module 51 1st Peltier element 52 Base 53 2nd Peltier element 54 Isolator 55, 56 Beam splitter 60 Cases 70, 71 72 Base 73 Rod SA, SA1 to SA4, SA11 to SA14, SA21 to SA28 Installation surface SB, SD Installation surface SC Optical axis surface C Optical axis

Claims (12)

It consists of a first and second optical member and a base, and the first optical member is mounted on the base directly or via a first base, and the second optical member is directly or a second base. In the optical module that is mounted on the base via and the light is transmitted and received between the first optical member and the second optical member,
The light characterized in that at least one of the first optical member, the first base, the base, the second optical member, or the second base has means for compensating for tolerances in manufacturing. module.   The optical module according to claim 1, wherein the first optical member is a lens, and the second optical member is a semiconductor laser.   The lens is a polygon having a plurality of installation surfaces around it, and the compensation means is at least two installation surfaces having different distances from the optical center of the lens to the installation surface, and the installation surface is used to compensate for tolerances. The optical module according to claim 2, wherein is selected.   The first base or the second base is a rectangular parallelepiped, and the compensation means has a short side and a long side of the rectangular parallelepiped, and the installation surface has a short side and a long side to compensate for tolerances. 2. The optical module according to claim 1, wherein the optical module is selected from sides.   The first base or the second base is a stepped base, the compensation means is a step, and the optimum step for compensating for tolerance is the first optical member or the second optical member. The optical module according to claim 1, wherein the optical module is selected as an installation surface.   A lens member having a plurality of installation surfaces, wherein at least one distance between each installation surface and the optical center is different.   7. The lens member according to claim 6, wherein normal lines of the plurality of installation surfaces are perpendicular to an optical axis of the lens, and the plurality of installation surfaces form a side surface of a polygonal column. .   The lens member according to claim 6 or 7, wherein a distance between each installation surface and the center of the optical axis is increased stepwise around the optical axis.   The lens member according to any one of claims 6 to 8, wherein the plurality of installation surfaces have installation surfaces parallel to one installation surface.   The lens member according to any one of claims 6 to 9, wherein the plurality of installation surfaces have a pair of installation surfaces perpendicular to one installation surface.   The lens member according to claim 6, further comprising an identification unit that identifies a predetermined installation surface.   The optical module or lens member according to claim 1, wherein a surface roughness Ra of at least one surface of the installation surface is 50 μm or more.

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