JP3429190B2 - Optical semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device which is used, for example, as a light source for optical communication and optically couples a semiconductor element and an optical fiber via a lens, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a known technique related to the structure of this type of optical semiconductor device, for example, Japanese Patent Laid-Open Nos. 5-37024, 4-261076 and 9-90.
174 and JP-A-6-289256.

The optical semiconductor device described in Japanese Patent Application Laid-Open No. 5-37024 is for optically coupling a semiconductor light emitting element and an optical fiber through a spherical lens. That is, a trapezoidal groove with an alignment pattern for fixing a semiconductor light emitting element, a cross-shaped V groove for fixing a spherical lens, and a V groove for fixing an optical fiber are formed from two semiconductor wafers. Are formed on the respective optical coupling substrates. The depths of the trapezoidal groove and the V groove are such that the laser emitting portion of the semiconductor light emitting element, the central portion of the spherical lens, and the central portion of the core of the optical fiber coincide with each other in size and shape of each optical device. Is set according to. Note that the position adjustment of the spherical lens is performed by tilting (deviation from the lens optical axis in the horizontal cross section, the same in the following description) and tilting (deviation from the lens optical axis in the vertical cross section, in the following specification). The same) can be ignored and does not affect the optical coupling efficiency. Therefore, it suffices to match the distance and height with the semiconductor light emitting element. Incidentally, Japanese Patent Application Laid-Open No. 4-261076 discloses an optical semiconductor device having substantially the same configuration.

The optical semiconductor device described in Japanese Unexamined Patent Publication No. 9-90174 performs optical coupling between a semiconductor laser and an optical fiber by a two-lens system having first and second lenses. The first lens is an aspherical lens that collimates the laser light emitted from the semiconductor laser, and the second lens collects the laser light collimated by the first lens and makes it enter the optical fiber. It is a spherical lens with its part cut out. Among them, the first lens is held by a lens holder welded and fixed to a base made of a metal material on which a semiconductor laser is installed. The first lens, which is an aspherical lens, is different from the above-described spherical lens in that the optical axis with the semiconductor laser must be minimized in addition to the distance and height from the semiconductor laser and the tilt and tilt of the lens must be minimized. It becomes impossible to obtain high coupling efficiency due to the shift. Therefore, with the semiconductor laser being driven, the distance / height between the semiconductor laser and the first lens and the inclination / tilt of the first lens should be adjusted so that the laser light passing through the first lens becomes parallel light. After adjusting, weld and fix to the base. Incidentally, JP-A-6-2
Japanese Patent No. 89256 also discloses an optical semiconductor device having substantially the same configuration.

[0005]

However, the above-mentioned conventional techniques have the following problems.

That is, since the optical semiconductor devices described in Japanese Patent Laid-Open Nos. 5-37024 and 4-261076 are optical coupling systems using spherical lenses with large aberrations, they have a converging property for laser light. become worse. As a result, the coupling efficiency between the semiconductor light emitting element and the optical fiber becomes low, and the level of the output light from the optical fiber becomes low. Therefore, in order to improve the level of the fiber output light, a method such as increasing the laser output emitted from the semiconductor light emitting element or improving the assembling accuracy to minimize the coupling loss between the semiconductor light emitting element and the optical fiber, etc. I have to take it. However,
The former needs to increase the drive current of the semiconductor light emitting element, which causes the disadvantages of increased power consumption and heat generation and shortened life of the semiconductor light emitting element, and the latter makes it difficult to reduce the component cost and the assembly cost.

Further, the optical semiconductor devices described in JP-A-9-90174 and JP-A-6-289256,
The first lens of the two lenses is an optical coupling system using an aspherical lens having less aberration than a spherical lens. Therefore, unlike the above-mentioned known example, the converging property of the laser light is improved, and the coupling efficiency between the semiconductor laser and the optical fiber can be increased. However, when assembling the first lens, which is an aspherical lens, the method is such that the semiconductor laser is driven to adjust the position of the aspherical lens and then the first lens is welded and fixed as described above. Special equipment is required to adjust the lens so that the laser light that has passed through is parallelized while being monitored. At this time, a large amount of time is required to adjust the distance / height between the semiconductor laser and the lens and the inclination / tilt of the lens. Further, since the first lens is held by the lens holder made of a metal material, which is welded and fixed to the base on which the semiconductor laser is installed, the assembling work becomes complicated. Further, there is also a problem that the cost of parts is increased by the amount corresponding to the lens holder, and the device is increased in size. An object of the present invention is to provide an optical semiconductor device capable of adjusting a position of an aspherical lens in a short time and easily without using special equipment and optically coupling a semiconductor element and an optical fiber with high efficiency. It is to provide the manufacturing method.

[0008]

(1) In order to achieve the above object, the present invention provides a semiconductor element including at least one of a semiconductor light emitting element and a semiconductor light receiving element, and a substrate member on which the semiconductor element is mounted. An optical semiconductor device having an optical fiber optically coupled to the semiconductor element for internally transmitting a laser beam, and a lens mounted on the substrate member and optically coupling the semiconductor element and the optical fiber, The substrate member has a groove portion whose axis is substantially in the same direction as the optical axis direction of the laser light between the semiconductor element and the optical fiber, and the lens has a cylindrical portion. A portion is directly fixed to the groove portion so as to make surface contact with the groove portion or line contact at least at two points , and the length of the cylindrical portion in the lens center axis direction is
t, where D is the outer diameter of the lens, (1/15) ≦
(T / D) <1 . Since the lens is directly fixed to the groove formed on the substrate member, the groove can be accurately formed at a predetermined depth by, for example, anisotropic etching, and the height of the semiconductor element and the lens can be adjusted without adjustment. be able to. Further, the axis of the groove is set to be a direction substantially parallel to the optical axis direction of the laser beam, and the cylindrical portion of the lens is brought into surface contact or line contact at at least two positions with respect to the groove. As a result, the surface that bisects the angle formed by the two surfaces of the surface contact (or the extension surface thereof) and the bisector of the angle formed by the two lines of the line contact (or the extension line thereof) form the axis of the groove. By preliminarily setting the lens to be parallel to the direction, the inclination of the lens can be set to zero only by installing the lens in the groove. Further, the lens is installed in the groove by appropriately setting the angle seen in the vertical cross section of the two surfaces of the surface contact or the two wires of the line contact, for example, by making line contact with two lines parallel to the optical axis direction of the laser light. Just by doing so, the tilt of the lens can be made zero. As described above, in adjusting the position of the lens, only the distance between the lens and the semiconductor element needs to be adjusted, and therefore it is sufficient to adjust the position while monitoring the distance with a simple monitor device. Therefore, even when an aspherical lens is used in order to improve the efficiency of optical coupling between the semiconductor element and the optical fiber, the semiconductor element is driven as in the conventional structure without using special equipment and can be used for a short time. Moreover, the position of the lens can be adjusted by an easy operation.

[0009]

[0010]

[0011]

Further, it can be prevented by a (t / D) ≧ (1/15 ), taking a sufficiently large length of the cylindrical portion to the outer diameter of the lens, to ensure the inclination of the lens. Further, by setting (t / D) <1, it is possible to prevent the aberration from increasing as in the case of the spherical lens, to secure the converging property of the laser light, and to surely increase the coupling efficiency.

(2) In the above (1), preferably,
When the distance from the semiconductor element to the cylindrical portion is L and the focal length of the lens is f, 0.7 × (1/2)
It is arranged so that × D ≦ L ≦ f. 0.7 x
By setting (1/2) × D ≦ L, it is possible to reliably prevent the distance from the semiconductor element to the tubular portion to be too small and the tubular portion to interfere with the end of the groove. Further, for example, in the case where a semiconductor element and an optical fiber are coupled by using two lenses, the laser light must enter and emit in the parallel direction at least on the side opposite to the semiconductor element side of the lens on the semiconductor element side. By so doing, it is possible to reliably prevent the distance from the semiconductor element to the cylindrical portion to become too large and the laser light to spread beyond the parallel direction.

(3) In the above (1), and preferably, the lens includes two curved portions located on both sides of the tubular portion and serving as a laser incident side end portion or a laser emitting side end portion. , T <D, where T 1 is the lens thickness from the front end of one curvature portion to the rear end of the other curvature portion and D is the outer diameter of the lens . During assembly,
Even if an attempt is made to bring the cylindrical portion closer to the semiconductor element in order to reduce the occurrence of optical coupling loss and improve the optical coupling efficiency, it may interfere with the end of the groove of the substrate member and cannot be brought closer to a certain extent. Since the incident side end portion is provided with the curved portion, even in such a case, the curved portion can be brought closer to the semiconductor element side than the tubular portion without interference. Therefore, it is possible to minimize the occurrence of optical coupling loss during assembly.

[0015]

[0016]

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in each drawing, in order to avoid complication, a part of the metallized wiring, wire bonding, adhesive, laser welding and the like are omitted as appropriate. A first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a horizontal sectional view showing the overall structure of the optical semiconductor device according to the present embodiment.

In FIG. 2, an optical semiconductor device includes a laser diode 1 as a semiconductor light emitting element and a photodiode 2 as a semiconductor light receiving element, and electronic component elements (not shown) for driving and controlling the laser diode 1 and the photodiode 2. No.), a silicon substrate 4 on which the laser diode 1, the photodiode 2 and the electronic component element are mounted, and an optical fiber (not shown; (Inside the ferrule 9), an aspherical lens 3 mounted on the silicon substrate 4 for optically coupling the laser diode 1 and the photodiode 2 with the optical fiber, and the laser diode 1 and the photodiode 2 outside the device. Metallized wiring 12 for electrical connection
The laser diode 1 has a lead terminal 7, a case 6 for accommodating the silicon substrate 4, an optical fiber inside, and a ferrule 9 attached to an end of a pipe 8 provided at one end of the case 6. Optical coupling between the photodiode 2 and the optical fiber is performed by the aspherical lens 3 alone.

The case 6 is made of, for example, a ceramic material having a box shape, and has lead terminals 7 on both sides thereof.
It has a total of eight books. A cap (not shown) for connecting the inside of the case 6 to the outside is joined to the upper surface of the case 6. The size of the box-shaped case 6 is, for example, 4.6 m in height (direction perpendicular to the paper surface in FIG. 2).
m, width (up and down direction in FIG. 2) is 7.4 mm, length (FIG. 2)
The horizontal direction) is 10.0 mm, and the lead terminal 7
Are provided at intervals of 2.54 mm, for example.

The pipe 8 is a metal member and is fixed to the case 6 in advance by silver brazing (not shown) before attaching the ferrule 9 (described later).

The ferrule 9 is composed of a zirconia member 10 in which the strands of the optical fiber are internally fixed and a metal member 11 in which the coating of the optical fiber is fixed.
When the ferrule 9 is attached, the laser light that has passed through the aspherical lens 3 is made incident on the optical fiber, and the position is adjusted so that the optical fiber output at that time is maximized. It is fixed to the end face by laser welding (not shown). The tip 14 of the optical fiber exposed at the tip of the zirconia member 10 is slanted as shown in FIG. 2 in order to prevent the laser light oscillated from the laser diode 1 from returning to the laser diode 1 as reflected return light at the tip 14 of the optical fiber. Has been processed into. At this time, the laser diode 1 and the aspherical lens 3 are arranged so that the laser light is efficiently incident on the obliquely processed optical fiber.
The laser beam is obliquely emitted by relatively displacing the optical axis of the laser beam by several tens of μm, and the silicon substrate 4 on which the laser diode 1 and the aspherical lens 3 are mounted is slightly shifted from the center of the case 6 to the lower side in FIG. By installing the laser light, the laser light passing through the aspherical lens 3 is emitted in the upward right direction in FIG.

FIG. 1 is a perspective view showing a lens mounting structure which is one of the features of the optical semiconductor device of this embodiment, and FIG. 3 (a) and FIG. 3 (b) are a longitudinal sectional view and a side view thereof, respectively. Show. In FIG. 1, FIG. 3A, and FIG. 3B, the laser diode 1 and the photodiode 2 are markers (not shown) on the metallized wiring 12 formed on the upper surface of the silicon substrate 4. ) Is used as a mark for positioning at predetermined positions. The laser diode 1 and the photo diode 2 are electrically connected to the metallized wiring 12 on the upper surface of the silicon substrate 4 via wire bonding 13.

A V-shaped groove 5 having a substantially V-shaped cross section is formed on the silicon substrate 4 by anisotropic etching. The V-shaped groove 5 has slopes 5a and 5b on both sides and a bottom surface 5.
and c (see FIG. 3B). Also, V
The axis of the groove 5 is substantially parallel to the optical axis direction of the laser light between the laser diode 1 and the photodiode 2 and the optical fiber. In addition, the V groove 5 is shown in FIG.
As shown in (b), the side surface shape and the cross-sectional shape are inverted isosceles trapezoids, and at this time, the vertical height of the bottom surface 5c is constant in the axial direction (that is, the bottom surface 5c is a horizontal plane).
Has become. The silicon substrate 4 has, for example, a thickness (vertical direction in FIG. 3A) of 1.0 mm and a V groove 5 depth of 0.78 mm.

The aspherical lens 3 has a substantially columnar shape with curvature on the incident end face and the emitting end face for the laser light emitted from the laser diode 1, and is mainly formed by glass molding or press molding. There is. Specifically, the aspherical lens 3 has a cylindrical portion 3a having a substantially cylindrical shape.
And two curvature portions 3b and 3c located on both sides of the tubular portion 3a and serving as a laser incident side end portion or a laser emitting side end portion, and the outer peripheral surface 15 of the tubular portion 3a is formed by the V groove 5. Line contact with both slopes 5a and 5b at two locations (Fig. 3
As shown in the line contact portion 16 in (b)), it is directly bonded and fixed with an adhesive (not shown) (detailed later). Also,
The dimensions of the lens 3 and its surroundings are the same as the cylindrical portion 3.
The lens center axial length t of a (see FIG. 3A), the outer diameter D of the lens 3 (same), and the lens thickness T from the front end of one curvature portion 3b to the rear end of the other curvature portion 3c. , And the distance L from the laser diode 1 to the cylindrical portion 3b is (1/15) ≦ (t / D) <1 0.7 × (D / 2) ≦ L ≦ 1.0 × (D / 2) It is constructed and arranged so that T <D. Specifically, for example, D = 1.5 mm, t = 0.2 to 0.3 mm, T =
It is 0.8 mm and L = 0.53 mm. The numerical aperture of the aspherical lens 3 is 0.55 and the focal length f = 0.7.
It is 8 mm.

Next, another method of fixing the lens to the V groove 5 of the silicon substrate 4, which is another feature of this embodiment, will be described with reference to FIG.
Will be explained.

When the lens 3 is fixed, first, the aspherical lens 3 is vacuum-sucked by the lens holding pipe 21 and conveyed, and mounted on the V groove 5 of the silicon substrate 4 on which the laser diode 1 and the photodiode 2 are mounted. Place. Next, lens 3
Lens holding pipe 21 with V groove 5
The position of the aspherical lens 3 in the V groove 5 is adjusted so that the distance between the laser diode 1 and the photodiode 2 on the silicon substrate 4 becomes a predetermined value by making a small movement in the axial direction.

When the distance reaches a predetermined value by adjustment, the wire member 2 attached to the wire holder 19 in that state.
0 is brought into contact with the outer peripheral surface 15 of the aspherical lens 3, the wire holder 19 is moved in the direction of the arrow in FIG. 4, and the aspherical surface is obtained with the wire member 20 along the outer peripheral surface 15 of the aspherical lens 3. The lens 3 is pressed against the V groove 5, and the aspherical lens 3
Hold it in its adjusted position. It should be noted that when the aspherical lens 3 is pressed by the wire member 20, there is no possibility that the aspherical lens 3 will be slightly deviated, but the amount of positional deviation at that time is 10 μm or less, and the amount of angular deviation is The inventors of the present application have confirmed that it is twice or less. It was found that if the positional shift amount and the angular shift amount are in this degree, the optical coupling efficiency between the laser diode 1 and the optical fiber does not significantly decrease, and there is no problem.

Then, with the aspherical lens 3 held at a predetermined position in the V groove 5, a portion where the adhesive (not shown) is in contact with the aspherical lens 3 and the V groove 5 (that is, FIG. 3B). )
(Corresponding to the line contact portion 16 of FIG. 3) and cured to fix the aspherical lens 3 to the V groove 5. As the adhesive at this time, an ultraviolet curable adhesive that can be cured in a short time while holding the aspherical lens 3 is preferable.

After fixing the aspherical lens 3 in this manner, the lens holding pipe 21 and the wire member 20 are removed from the aspherical lens 3, respectively.

The operation and effect of this embodiment having the above-described configuration will be sequentially described below.

(1) Function and effect of the lens mounting structure Since the aspherical lens 3 is directly fixed to the V groove 5 formed in the silicon substrate 4 by anisotropic etching, the V groove 5 is previously formed with a predetermined depth. The laser emitting portion of the laser diode 1 and the photodiode 2 can be formed by forming them with high precision.
The heights of the optical axes of the laser incident part and the aspherical lens 3 can be adjusted without adjustment. The axis of the V groove 5 is substantially parallel to the optical axis direction of the laser light, and the outer peripheral surface 15 of the cylindrical portion 3a of the aspherical lens 3 has two line contact portions 16 with respect to the V groove 5. The line contact at
The inclination of the aspherical lens 3 becomes zero only by installing the aspherical lens 3 in the V groove 5 (that is, the central axis direction of the aspherical lens 3 matches the optical axis direction of the laser light). Furthermore, V
The groove 5 has an inverted isosceles trapezoidal side surface shape and a lateral cross-sectional shape, and the vertical height of the bottom surface 5c is constant in the axial direction, so that the cylindrical portion 3a of the aspherical lens 3 is formed into the V groove 5. The tilt of the aspherical lens 3 can be reduced to zero by simply installing the lens in. As a result, in adjusting the position of the aspherical lens 3, as described above with reference to FIG. 4, the position between the front surface of the aspherical lens 3 and the laser emitting portion of the laser diode 1 or the laser incident portion of the photodiode 2 is adjusted. Since it is only necessary to adjust the distance, it is sufficient to adjust the distance while measuring it with a simple monitor device, for example. Therefore, the position adjustment of the aspherical lens 3 can be performed in a short time and with a simple operation without using special equipment while driving the semiconductor element as in the conventional structure. Further, since the aspherical lens 3 is directly fixed to the V groove 5 without using a lens holder as in the conventional structure, it is possible to reduce the cost by reducing the number of parts and the working process, and to downsize the device. It is also possible to realize double-sided mounting on a printed circuit board.

(2) Function and effect of the lens fixing method When fixing the aspherical lens 3 to the V groove 5 of the silicon substrate 4, the aspherical lens 3 is fixed to the V groove 5 by the elastic wire member 20.
By holding and fixing in the groove 5, the lens outer peripheral surface 15
The lens outer peripheral surface 15 can be mounted so as to follow the V groove 5 naturally without applying an extra external force to the contact portion (line contact portion 16) of the V groove 5. Therefore, since the aspherical lens 3 can be stably positioned and fixed, in addition to the effect of the above (1), the inclination / tilt of the aspherical lens 3 can be prevented more reliably, and high optical coupling efficiency can be secured. . In particular, it is effective when the aspherical lens 3 has a small diameter and a thin wall thickness.

(3) Effect of setting t / D If t / D is too small, the length of the tubular portion with respect to the lens outer diameter is not sufficient, and it may be difficult to prevent the lens from falling. (See FIG. 3A). The inventors of the present application have studied various values of t / D, and as a result, t / D is set as the lower limit of t / D that can surely prevent the lens from falling.
It was determined that = 1/15 was appropriate. On the other hand, t / D = 1
In that case, the lens becomes substantially closer to a spherical lens, so that the aberration becomes large and the condensing property of the laser light is deteriorated, so that it is difficult to improve the coupling efficiency. In the present embodiment, as described above, the length t of the cylindrical portion 3a in the central axis direction of the lens and the outer diameter D of the aspherical lens 3 are (1/15) ≦ (t / D) <1. . As a result, it is possible to more reliably prevent the aspherical lens 3 from collapsing, and it is possible to reliably maintain high coupling efficiency.

(4) If the operational effect L due to the setting of L is too small, the distance from the laser diode 1 to the tubular portion 3a becomes too small, and the tubular portion 3a may interfere with the end of the V groove 5. Yes (see FIG. 3 (a)). The inventors of the present application conducted various examinations by changing the values of L and D in consideration of the end surface slope shape of the V groove 5 by anisotropic etching. As a result, the lower limit value of L that can reliably prevent the interference is 0. It was judged that 0.7 × (D / 2) was appropriate. On the other hand, the laser light emitted from the laser diode 1 usually has a divergence angle of about 30 degrees, but if L becomes too large, the diverged laser light may not sufficiently enter the aspherical lens 3. The inventors of the present application have studied various values of L and D, and as a result, as the upper limit value of L at which laser light can be sufficiently incident on the aspherical lens 3, 1.0 × (D /
2) was judged to be appropriate. As a typical example for realizing the range of L, the numerical aperture of the aspherical lens 3 is 0.5 to 0.6, and the focal length of the aspherical lens 3 is 0.7 to 0. It may be 9 mm. In the present embodiment, as described above, the numerical aperture of the aspherical lens 3 is 0.55, the focal length is 0.78 mm, and the distance L from the laser diode 1 to the tubular portion 3a is 0.7 × (D /
2) ≦ L ≦ 1.0 × (D / 2) is set. As a result, it is possible to reliably prevent the cylindrical portion 3a from interfering with the end portion of the V groove 5, and it is possible to reliably and efficiently make the laser light from the laser diode 1 enter the aspherical lens 3.

(5) Others When assembling the aspherical lens 3, even if the cylindrical portion 3a is brought closer to the laser diode 1 in order to reduce the generation of optical coupling loss and improve the optical coupling efficiency, V of the silicon substrate 4 will be used.
In some cases, the end of the groove 5 interferes with the groove 5 and cannot be brought closer to a certain extent. However, in the present embodiment, the aspherical lens 3 has a curved portion 3b at the end on the laser incident side. Also in this case, the curved portion 3b can be brought closer to the laser diode 1 side than the cylindrical portion 3a without interference. Therefore, it is possible to minimize the occurrence of optical coupling loss during assembly.

In the first embodiment, the optical semiconductor device having both the laser diode 1 and the photodiode 2 as the semiconductor element has been described as an example, but the present invention is not limited to this, and either one of them is used. It can be applied to an optical semiconductor device including only the same, and the same effect can be obtained.

In the first embodiment, the distance between the aspherical lens 3 and the laser diode 1 is adjusted while the distance is measured by the monitor device. A mark (not shown) for aligning the aspherical lens 3 may be provided on the substrate 4, and the aspherical lens may be mounted on the substrate 4 so as to be a predetermined distance. Also in this case, the same effect is obtained.

Further, in the first embodiment described above, the V groove 5 is formed in the silicon substrate 4 for fixing the aspherical lens 3, but the present invention is not limited to this, and, for example, the cross-sectional shape is substantially the same. It may be a trapezoidal shape (not an isosceles trapezoid) or a substantially rectangular groove. Similar effects are obtained in these cases as well.

Further, in the first embodiment, the adhesive is applied to the line contact portion 16 in a state where the aspherical lens 3 is installed in the V groove 5 and pressed, but the present invention is not limited to this, and the line contact portion 16 is not limited to this. Of these, an adhesive may be applied in advance to the portion where the aspherical lens 3 is installed. Also in this case, the same effect is obtained.

Further, in the first embodiment,
A wire member 20 as a member for pressing the aspherical lens 3
Was used, but is not limited to this. That is, a member having elasticity such that an external force is not applied when the outer peripheral surface 15 of the aspherical lens 3 makes a line contact with the surface of the V groove 5, a tape member, a spring member, an impact absorbing member, and Other constituent members including these members may be used. At this time, for example, the tip shape may be a pin shape, a flat shape, a V-shape, or the like. Similar effects are obtained in these cases.

In the first embodiment, the size of the box-shaped case 6 is 4.6 mm in height and 7.4 m in width.
However, the length is not limited to these. That is, in order to enable double-sided mounting on a printed circuit board, the height of the case 6 is at least 4.7.
It is sufficient if it is less than or equal to mm. In order to set the height of the case 6 to 4.7 mm or less, it is sufficient to set the outer diameter D of the aspherical lens 3 mounted in the case 6 to 2.0 mm or less, and D = 1 as in the present embodiment. It is not limited to 0.5 mm.

Further, in the first embodiment,
As shown in FIG. 3B, the lens outer peripheral surface 15 and the V groove 5 are in line contact with each other at the two line contact portions 16 and 16, but not limited to this, and the line contact is made at three or more places. Good. For example, it is conceivable that the height of the bottom surface 5c is further raised and the bottom surface 5c is also brought into line contact with the lowermost portion of the lens outer peripheral surface 15. Similar effects are obtained in these cases as well. Further, the contact is not limited to the line contact, and the V groove 5 may be in surface contact with two surfaces. A modified example in this case will be described with reference to FIG. Figure 5
[Fig. 3] is a side view showing a lens mounting structure in this modified example, which is substantially equivalent to Fig. 3 (b) of the first embodiment. As shown in FIG. 5, in this modified example, the tubular portion 3a of the aspherical lens 3 has a substantially polygonal tubular shape (to be exact, a dodecagonal tubular shape), and two of the outer peripheral portions 15 thereof are provided. The two surfaces 15a and 15b form a surface contact portion 22 between the two slopes 5a and 5b of the V groove 5. That is, the substantially polygonal tubular shape of the tubular portion 3a is formed in advance so as to match the angles (for example, 54.7 °) of the slopes 5a and 5b of the V groove 5 formed by anisotropic etching. Surface 1
Surface contact with 5a and 15b is possible. Similar to the first embodiment, the aspherical lens 3 having the substantially polygonal tubular portion 3a can be easily formed by mainly glass molding or press molding without the need for post-processing. The polygonal shape of the outer peripheral surface 15 of the tubular portion 3a is not limited to the regular polygon. Further, the tubular portion 3a is not limited to the substantially polygonal tubular shape, and may have a tubular shape in which the outer peripheral surface 15 has a mixture of a curved surface and a flat surface. In this modification,
Since they are in surface contact, there is an effect that the aspherical lens 3 can be mounted in the V groove 5 in a more stable state than in the first embodiment.

Needless to say, the surface contact is not limited to the two surfaces, and the surface contact may be made on three or more surfaces.

A second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a horizontal sectional view showing the overall structure of the optical semiconductor device according to the present embodiment.

In FIG. 6, the optical semiconductor device according to the present embodiment is the same as the optical semiconductor device of the first embodiment except that an optical isolator 17 for antireflection and a glass plate for hermetically sealing the case 6 are used. This is a structure in which 18 are additionally fixed.

The optical isolator 17 has an outer diameter of 2.0, for example.
It has a length of 2.6 mm and a length of 2.6 mm, and is incorporated in advance as a part of the ferrule 9 with an optical isolator so as to be positioned at the optical fiber tip 14 of the zirconia member 10. At this time, the optical isolator 17 is fixed to the optical fiber tip 14 with an adhesive (not shown) having a high laser light transmittance so that the optical isolator 17 is closely adhered to the optical fiber tip 14 so that no space remains. As the adhesive, an ultraviolet curable adhesive or a thermosetting adhesive is preferable, and as the ultraviolet curable adhesive, a thermosetting combined type adhesive is desirable. Further, the optical isolator 17 having such a structure can perform position adjustment together with the ferrule 9 without using a holder member or the like for holding and fixing the optical isolator 17 alone. That is, the ferrule 9 with the optical isolator 17 is installed on the end face of the pipe 8, the laser light that has passed through the aspherical lens 3 is incident on the optical fiber, and the ferrule 9 is position-adjusted so that the optical fiber output is maximized. Metal member 11 of ferrule 9
Is fixed to the end surface of the pipe 8 by laser welding (not shown).
In this way, the adjustment can be performed in substantially the same manner as the optical fiber position adjusting method shown in the first embodiment.

The glass plate 18 is installed on the side wall of the case 6 between the aspherical lens 3 and the optical isolator 17. The glass plate 18 is joined to the side wall of the case 6 with low melting point glass or Au80-Sn20 eutectic solder (not shown).
At this time, in order to prevent the laser light passing through the aspherical lens 3 from returning to the laser diode 1 as reflected return light, it is obliquely attached as shown in the figure. The material of the glass plate 18 is, for example, sapphire, and a multi-layer antireflection film is formed on the incident surface and the emission surface of the laser light.

The other structure is almost the same as that of the first embodiment.

According to this embodiment, in addition to the same effects as those of the first embodiment, the following effects are obtained. That is, by installing the optical isolator 17 between the aspherical lens 3 and the optical fiber, most of the return light returned to the laser diode 1 due to reflection at the tip 14 of the optical fiber or reflection from the system side is eliminated and reduced. can do. Therefore, the laser diode 1 can be operated more stably and at a higher speed than in the optical semiconductor device of the first embodiment, and an optical semiconductor device with an increased transmission capacity can be realized. Further, since the glass plate 18 is attached to the side wall of the case 6 and the cap (not shown) is attached to the upper surface of the case 6, the inside of the case 6 can be completely hermetically sealed. It is possible to prevent the unstable operation and the shortening of the life of No. 1 and improve the reliability.

In the above first and second embodiments, the optical semiconductor device in which the laser diode 1 and the photodiode 2 and the optical fiber are optically coupled by the single aspherical lens 3 has been described as an example. It is not limited to this. That is, as long as it is a coupling optical system using at least one aspherical lens, the same structure and method as those of the first and second embodiments can be applied to the mounting structure and mounting method of the aspherical lens 3. Therefore, similar effects can be obtained in these cases. Further, when forming a coupling optical system using a plurality of lenses including at least one aspherical lens 3 as described above, the upper limit of the setting of L described in (4) in the first embodiment is more It can be big. That is, for example, in the case where the laser diode 1 and the optical fiber are coupled by using two lenses and the aspherical lens 3 is used as the lens on the laser diode 1 side, the rear surface side of the aspherical lens 3 (anti-photodiode) is used. It is sufficient for the first side) to emit laser light at least in the parallel direction. In this case, if the value of L is equal to or less than the focal length f, it is possible to reliably prevent the laser light from spreading beyond the parallel direction. Therefore, the upper limit value of L is set to f. That is, the setting of L in this case is 0.7 × (D
/ 2) ≦ L ≦ f.

[0052]

According to the present invention, the position of the aspherical lens can be adjusted in a short time and with a simple operation without using special equipment, and the semiconductor element and the optical fiber can be optically coupled with high efficiency. it can.

[Brief description of drawings]

FIG. 1 is a perspective view showing a lens mounting structure which is a main part of an optical semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a horizontal sectional view showing the overall structure of the optical semiconductor device shown in FIG.

3 is a vertical sectional view and a side view of the structure shown in FIG.

FIG. 4 is a diagram showing a method of fixing a lens to a V groove of a silicon substrate.

FIG. 5 is a side view showing a lens mounting structure in a modified example of the first embodiment.

FIG. 6 is a horizontal sectional view showing the overall structure of an optical semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

1 Laser diode (semiconductor light emitting device) 2 Photodiode (semiconductor light receiving element) 3 Aspherical lens (lens) 4 Silicon substrate (substrate member) 5 V groove (groove part) 6 cases 7 Lead terminal 8 pipes 9 ferrules 12 Metallized wiring 13 wire bonding 15 Lens outer peripheral surface 16 line contact area 19 Wire holder 20 Wire member (holding member) 21 Lens holding pipe (adsorption member) 22 Contact area

Front page continuation (72) Inventor Koji Yoshida 1-280, Higashi Koikekubo, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. 72) Inventor Tadaaki Ishikawa 502 Jinrachi-cho, Tsuchiura-shi, Ibaraki Machinery Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-7-199006 (JP, A) JP-A-7-199007 (JP, A) JP Flat 7-120638 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 6/42 G02B 6/32 H01L 31/0232 H01L 33/00

Claims (3)

(57) [Claims] 1. A semiconductor element comprising at least one of a semiconductor light emitting element and a semiconductor light receiving element, a substrate member on which the semiconductor element is mounted, and an optical fiber optically coupled to the semiconductor element for internally transmitting laser light. An optical semiconductor device mounted on the substrate member and having a lens for optically coupling the semiconductor element and the optical fiber, wherein the substrate member has a laser beam between the semiconductor element and the optical fiber. Is provided with a groove portion that is substantially in the same direction as the optical axis direction of the lens, and the lens has a cylindrical portion, and this cylindrical portion is in surface contact with the groove portion or in line contact with at least two locations. Is fixed directly to the groove portion , and
Let t be the length in the direction of the central axis of the lens, and let the outer diameter of the lens be
When the D, (1/15) ≦ (t / D) < optical semiconductor device characterized by being configured so that 1. 2. The optical semiconductor device according to claim 1 , wherein the distance from the semiconductor element to the cylindrical portion is L and the focal length of the lens is f, 0.7 × (D / 2) ≦ An optical semiconductor device, which is arranged so that L ≦ f. 3. The optical semiconductor device according to claim 1, wherein the lens has two curved portions located on both sides of the tubular portion and serving as a laser incident side end portion or a laser emitting side end portion, When the lens thickness from the front end of the one curvature portion to the rear end of the other curvature portion is T and the outer diameter of the lens is D , T <D Semiconductor device .