JP2005164799A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module having a simple configuration capable of improving a packaging precision. <P>SOLUTION: The optical module is equipped with a semiconductor optical element 10 characterized in having a protrusion 11 nearly parallel to an optical axis on the surface on the side of a light-emission area and an electrode part 12 on the upper-end surface of the protrusion 11 so that the electrode part 12, the protrusion 11, and an active area are on the same axis and a mounting substrate 30 characterized in having a recessed groove 31 which is nearly parallel to the optical axis and having its groove opening width wider than its bottom surface width and a groove 32 where an optical fiber 20 is fixed, the semiconductor optical element 10 being mounted and positioned using irregular shapes by fitting the protrusion 11 of the semiconductor optical element 10 in the recessed groove 31 of the mounting substrate 30. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical module in which a semiconductor laser and an optical fiber used in the field of optical communication and the like are mounted on the same mounting substrate.

  Along with the explosive spread of the Internet, in an optical transmission system for access such as FTTH, a significant reduction in cost is desired for optical terminals installed in subscriber homes. As a cost factor of the optical terminal, devices related to the optical module such as a laser module and a photodiode module and optical mounting costs occupy a large proportion. Among these, for optical mounting, a passive alignment method is used to align the optical axes of the semiconductor laser and the optical fiber, thereby reducing costs.

  Some conventional optical modules using the passive alignment method use a marker pattern. For example, in FIG. 6, the optical module includes a semiconductor laser 610 having a marker pattern 611, an optical fiber 620, a V-groove 632 for mounting the optical fiber 620, and a mounting substrate 630 having a marker pattern 631. Since the optical fiber 620 is mechanically positioned and fixed in a V-shaped groove 632 formed by photolithography and anisotropic etching, highly accurate positioning is possible. On the other hand, the semiconductor laser 610 aligns the marker pattern 611 and the marker pattern 631 using infrared transmitted light.

In addition, some conventional optical modules using the passive alignment method utilize concavity and convexity fitting instead of the marker pattern. For example, in FIG. 7, the optical module includes a semiconductor laser 710 having a convex portion 711, an optical fiber 720, a V-groove 732 for mounting the optical fiber 720, a concave portion 731, and a mounting substrate 730 having a concave portion 732. The semiconductor laser is aligned by fitting the convex portion 711 to the concave portion 731. In addition, as a conventional method using the concavity and convexity fitting for the alignment of the optical element, for example, an optical module described in Patent Document 1 can be cited.
JP 2001-194559 A

  However, in the conventional method that uses only the marker pattern or the concavity and convexity fitting for the alignment of the semiconductor laser, the marker pattern or the concavity and convexity position and the emission region of the semiconductor laser depend on the manufacturing accuracy of the marker pattern or concavity and convexity production position. An error occurs in the relative distance D1 or D2. As a result, the optical axis deviation between the semiconductor laser and the optical fiber varies, and there is a problem that the yield of light output efficiency in the optical module is lowered.

  The present invention solves the above-mentioned conventional problems, and in an optical module using a passive alignment method for optical axis alignment of a semiconductor optical device and an optical fiber, the mounting accuracy is higher than that of a conventional method using alignment markers or concavity and convexity fitting. It aims at realization of the optical module of the simple composition which can improve.

  A first invention is an optical module in which a semiconductor laser and an optical fiber are optically coupled to each other on the same mounting substrate, and the semiconductor laser is substantially parallel to the optical axis of the output light on the surface of the light emitting region. The mounting substrate has an electrode window on the protrusion upper end surface of the protrusion, and the mounting substrate has a fiber fixing portion on which the optical fiber is mounted in a groove structure substantially parallel to the optical axis of the output light of the semiconductor laser. The semiconductor laser is provided with a concave groove portion substantially parallel to the optical axis of the output light of the semiconductor laser, and the optical axis alignment between the semiconductor laser and the optical fiber is performed by fitting the convex portion of the semiconductor laser with the concave groove portion of the mounting substrate.

  According to a second aspect of the present invention, in the optical module of the first aspect, the width of the protrusion upper end surface of the semiconductor laser in the cross section perpendicular to the optical axis of the output light of the semiconductor laser is at least the width of the protrusion lower end surface of the protrusion. It is wider than the width.

  According to a third aspect of the present invention, in the optical module of the first or second aspect of the invention, the opening width of the concave groove in the cross section perpendicular to the optical axis of the output light of the semiconductor laser is the bottom width and the convex portion of the semiconductor laser. It is wider than the width of the upper end surface of the protrusion, the groove depth of the concave groove portion is deeper than the height of the protrusion of the convex portion, and the groove width at a depth substantially equal to the height of the protrusion of the convex portion is It is wider than the width.

  According to a fourth invention, in the optical module of the first, the third or the third invention, the convex portion of the semiconductor laser and the concave groove portion of the mounting substrate are formed by anisotropic etching.

  According to a fifth invention, in the optical module according to any one of the first to fourth inventions, the semiconductor laser has a ridge waveguide structure.

  In an optical module that uses the passive alignment method for aligning the optical axis of a semiconductor laser and an optical fiber, an electrode is formed on the upper surface of the protrusion located on the semiconductor laser to the concave groove where the opening width of the groove located on the mounting substrate is wider than the bottom surface width. By fitting the convex part having a window and positioning using the difference between the width of the upper end surface of the convex protrusion and the groove width at the depth at which the upper end of the protrusion is in contact with the concave groove, compared to the conventional method, It is possible to realize an optical module capable of improving the mounting accuracy with a simple configuration regardless of the mask accuracy at the time of producing the convex portion.

(Embodiment 1)
FIG. 1 is a schematic perspective view of an optical module according to Embodiment 1 of the present invention, and FIG. 2 is a schematic cross-sectional view taken along a plane perpendicular to the optical axis of output light from a semiconductor laser.

  In FIG. 1, 10 is a semiconductor laser, 20 is an optical fiber, 30 is a mounting substrate on which the semiconductor laser 10 and the optical fiber 20 are mounted, and 11 is an output of the semiconductor laser 10 located on the light emitting region side of the semiconductor laser 10. A convex portion whose longitudinal direction is substantially parallel to the optical axis of the light, 12 is an electrode window portion located on the upper end surface of the projection of the convex portion 11, and 31 is an optical axis of the output light of the semiconductor laser 10 and the longitudinal direction of the groove is substantially parallel. The concave groove 32 is a fiber fixing part on which the optical fiber is mounted. The semiconductor laser 10 is mounted on the mounting substrate 30 by fitting the convex portion 11 to the concave groove portion 31.

  Hereinafter, the operation of the optical module according to Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 2, reference numeral 13 denotes an active layer of the semiconductor laser 10, and reference numeral 14 denotes a light emitting region that outputs light from a part of the active layer 13. A bias current applied via the electrode window 12 of the semiconductor laser 10 is injected from the electrode window 12 to the convex portion 11 and from the convex portion 11 to the active layer 13. Here, not all of the active layer 13 emits light, but only the region where the bias current is injected in the active layer 13 emits light, so that the light emitting region 14 is located immediately above the electrode window 12. By this injected current, light substantially parallel to the convex portion 11 is emitted from the light emitting region 14. This emitted light is incident on the optical fiber 20 mounted on the fiber fixing portion 32.

  As described above, according to the present configuration, the electrode window portion 12 is located on the upper end surface of the protrusion of the protrusion 11, so that the region immediately above the protrusion 11 becomes the light emitting region 14 regardless of the manufacturing position error of the protrusion 11. The convex portion 11 and the light emitting region 14 used for alignment are positioned on substantially the same axis.

  Therefore, it is possible to suppress the production error of the relative distance between the position of the convex portion used for positioning and the light emitting region of the semiconductor laser, and to suppress the variation in the optical axis deviation between the semiconductor laser and the optical fiber, and thus to improve the yield. The effect is obtained.

  The fiber fixing portion 32 has a V-groove structure formed by anisotropic etching using a pattern drawn on the mounting substrate 30 by a photolithography method or the like, and the depth of the groove is the width of the groove. It is determined with high accuracy according to. The fiber fixing portion 32 and the concave groove portion 31 are misaligned between the concave groove portion 31 and the fiber fixing portion 32 when, for example, photolithography is used to prepare respective masks simultaneously and etching is performed using the mask. Can be suppressed.

  The optical fiber 20 may be placed on the fiber fixing portion 32 and fixed with resin or the like.

(Embodiment 2)
FIG. 3 is a schematic cross-sectional view taken along a plane perpendicular to the optical axis of the semiconductor laser output light of the optical module according to Embodiment 2 of the present invention.

  In FIG. 3, 10 is a semiconductor laser, 12 is an electrode window portion, 13 is an active layer, 14 is a light emitting region, 15 is a convex portion, 30 is a mounting substrate, and 31 is a concave groove portion. Since the semiconductor laser 10 and the optical fiber 20 are mounted on the mounting substrate 30 in the same manner as in the first embodiment, description of each operation is omitted here.

  Here, in the second embodiment, the shape of the convex portion 15 is different from that of the first embodiment, so that the width W1 of the protrusion upper end surface of the convex portion 15 is larger than the width W0 of the protrusion lower end surface of the convex portion 15. Is formed. Therefore, in the second embodiment, in addition to the effects described in the first embodiment, the current injected into the active layer 13 is narrowed by the width W0 of the lower end surface of the protrusion, and the bias current is reduced. The light emitting region 14 is narrowed by the current, and the effect of improving the stability of the vertical transverse mode of the semiconductor laser 10 is obtained.

(Embodiment 3)
FIG. 4 is a schematic cross-sectional view taken along a plane perpendicular to the optical axis of the semiconductor laser output light of the optical module according to Embodiment 3 of the present invention. Since the semiconductor laser and the optical fiber are mounted on the mounting substrate in the same manner as in the first and second embodiments, description of each operation is omitted here.

  In FIG. 4, 10 is a semiconductor laser, 12 is an electrode window part, 13 is an active layer, 14 is a light emitting region, 15 is a convex part, 30 is a mounting substrate, and 33 is a concave groove part.

  Here, the shape of the concave groove portion 33 is different from that of the second embodiment, and the side surface of the concave groove portion 33 is inclined so that the opening width W3 of the concave groove portion 33 is wider than the bottom surface width W2 of the concave groove portion 33. The opening width W3 of the concave groove 33 is wider than the width W1 of the upper end surface of the protrusion 15 and the depth of the groove of the concave groove 33 is deeper than the height H1 of the protrusion of the convex 15. The concave groove portion 33 is formed such that the groove width W2 at a depth substantially coincident with the height H1 of the portion 15 is wider than the width W1 of the protrusion upper end surface of the convex portion 15. Therefore, in the third embodiment, in addition to the effects described in the first and second embodiments, the opening width W3 of the concave groove 33 is wider than the width W1 of the upper end surface of the protrusion 15 so that the protrusion The effect of reducing the mounting accuracy when fitting 15 into the concave groove 33 and the effect of suppressing the positioning error in the X-axis direction between the semiconductor laser 10 and the mounting substrate 30 within ± (W2−W1) / 2 are obtained.

  Note that the conventional method using only the alignment marker requires a highly accurate mounting device (mounting accuracy ± 1 μm). For example, when W1 and W2 are processed using a photolithography method, submicron accuracy can be realized. Therefore, mounting accuracy equal to or higher than that of the conventional method can be realized without using a high-accuracy mounting device.

(Embodiment 4)
FIG. 5 is a schematic cross-sectional view showing a manufacturing process of the semiconductor laser 10 of the optical module according to the first, second and third embodiments of the present invention. As shown in FIG. 5A, first, the lower cladding layer 110, the active layer 120, the upper cladding layer 130, the etch stop layer 140, and the upper cladding layer 150 are crystallized on the semiconductor substrate 100 by MO-CVD or the like. Grow. Next, a SiO2 layer is formed on the upper clad layer 150 by a thermal CVD method, etc., a convex upper end surface pattern is drawn on the SiO2 by photolithography, etc., and pattern transfer is performed on the SiO2 layer by etching, and an SiO2 mask 160 is produced. Next, by using the SiO 2 mask 160 as a mask, a convex portion 170 as shown in FIG. 5B is produced by etching. As an etching solution, wet etching is performed using an aqueous solution that etches only the upper cladding layer 150 without etching the etch stop layer 140. For example, when the cladding layer is made of InP and the etch stop layer is made of InGaAsP, wet etching with a mixed aqueous solution of hydrogen bromide and phosphoric acid or the like may be performed. Next, an insulating film layer such as SiO2 is formed on the surface on the convex portion 170 side, an electrode window pattern is drawn on the insulating film layer on the upper end surface of the convex portion by photolithography, etc., pattern transfer is performed by etching, and the electrode window The part 190 is produced. An electrode part is formed on the surface including the electrode window part 190, and current is injected into the active layer 120 through the electrode window part 190. In addition, the said manufacturing process is an example of the manufacturing process of a ridge waveguide type semiconductor laser, You may use manufacturing processes other than the above.

  The optical module according to the present invention has an effect that a mounting accuracy equal to or higher than that of the conventional method can be realized without using a high-accuracy mounting device, such as a light source such as an optical transmitter used for optical communication, etc. Useful as.

The perspective schematic diagram of the optical module in Embodiment 1 of this invention Sectional schematic diagram in a plane perpendicular to the output optical axis of the optical module according to Embodiment 1 of the present invention. Sectional schematic diagram in a plane perpendicular to the output optical axis of the optical module in Embodiment 2 of the present invention Sectional schematic diagram in a plane perpendicular to the output optical axis of the optical module in Embodiment 3 of the present invention Sectional schematic diagram which shows the manufacturing process of the semiconductor laser of the optical module in Embodiment 1 of this invention Perspective schematic diagram of a conventional optical module using a marker pattern Perspective schematic diagram of a conventional optical module that uses indentation fitting

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor laser 11,15 Convex part 12 Electrode window part 20 Optical fiber 30 Mounting board 31,33 Concave groove part 32 Fiber fixing part

Claims (5)

An optical module that optically couples a semiconductor laser and an optical fiber facing each other on the same mounting substrate,
The semiconductor laser has a convex portion substantially parallel to the optical axis of the output light on the surface on the light emitting region side, and an electrode window on the upper end surface of the projection of the convex portion,
The mounting substrate includes a fiber fixing portion on which the optical fiber is mounted with a groove structure substantially parallel to the optical axis of the output light of the semiconductor laser, and a concave groove portion substantially parallel to the optical axis of the output light of the semiconductor laser. ,
An optical module characterized in that the optical axis alignment of the semiconductor laser and the previous optical fiber is performed by fitting the convex part of the semiconductor laser and the concave groove part of the mounting substrate. In a cross section perpendicular to the optical axis of the output light of the semiconductor laser,
2. The optical module according to claim 1, wherein the width of the upper end surface of the protrusion of the convex portion of the semiconductor laser is at least wider than the width of the lower end surface of the protrusion of the convex portion of the semiconductor laser. In a cross section perpendicular to the optical axis of the output light of the semiconductor laser,
The opening width of the concave groove portion of the mounting substrate is wider than the bottom surface width and the width of the protrusion upper end surface of the convex portion of the semiconductor laser,
The depth of the groove of the concave groove is deeper than the height of the protrusion of the convex portion,
3. The optical module according to claim 1, wherein a groove width at a depth substantially equal to a height of the protrusion of the convex portion is wider than a width of an upper end surface of the protrusion of the convex portion. The convex part of the semiconductor laser and the concave groove part of the mounting substrate are
The optical module according to claim 1, wherein the optical module is formed by anisotropic etching. The semiconductor laser is:
The optical module according to claim 1, wherein the optical module has a ridge waveguide structure.

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