JP2009230031A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module in which the positioning of a lens is performed readily, including the adjustment of the height from the mounting face on a base, and for which workability is superior and cost is small. <P>SOLUTION: The optical module 10 comprises: a light-emitting element; an optical system including the lens for inputting the emitted light from the optical element to an optical fiber; a lens-holding member 15 which positions and holds the lens; and the base 14, which mounts these components where the lens holding member 15 has lens holding faces 15a to 5e, which are step-formed having heights which change successively from the base 14. The lens is held on a selected lens-holding face so that the light emitted from the light-emitting element is made incident on the optical fiber, at an optical coupling rate which is not less than a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical module including an optical system that optically couples signal light emitted from a light emitting element to an optical fiber.

  In recent optical modules used for optical communication, a light emitting element such as a semiconductor laser and an optical fiber are positioned with high accuracy to realize optical coupling. The light emitting element is mounted in the housing via a chip carrier, and the optical fiber is held in the housing together with a holding member such as a ferrule. An optical system such as a lens is positioned and fixed in the housing by YAG welding or the like with a lens holding member.

The positioning of the light emitting element and the lens is determined by the dimensional accuracy of the chip carrier and the lens holding member. After that, while monitoring the optical power through the optical fiber, the position of the optical fiber holding member is adjusted so that predetermined optical coupling is obtained. Adjustments have been made. At this time, when the optical axis of the optical system is largely deviated due to variations in dimensional accuracy between the light emitting element and the lens, the predetermined optical power may not be obtained no matter how much the position of the optical fiber is adjusted. .
Therefore, it has been conventionally performed to mount the lens by selecting an optimum position in the mounting plane. However, in the height direction perpendicular to the mounting plane, it is necessary to devise such as adjusting the thickness of the lens holding member.

  For example, in Patent Document 1, as shown in FIG. 5A, an optical element 1 such as a laser diode or a photodiode placed on a chip carrier 2 and a lens 3 held in a lens holder 4 are used as a base. An optical module that is mounted on the member 5 and optically coupled is disclosed. Then, a wedge-shaped pedestal 6 is interposed between the lens holder 4 and the base member 5 constituting the optical module. For example, by moving the pedestal 6 onto the base member 5, two-dimensional directions (XY) and Position adjustment within the plane of the rotation direction (θ1) is performed, and the lens holder 4 is slid along the slope of the pedestal 6 to adjust the position in the height direction (Z), and by rotating, the position adjustment in the tilt direction (θ2) is performed. Is going.

Further, in Patent Document 2, as shown in FIG. 5B, the light emitting element 1 placed on the chip carrier 2 and the lens 3 housed in the lens cylinder 7 are mounted on a holding block 8. An optically coupled light emitting module is disclosed. The holding block 8 has a structure in which a flat portion 8a for fixing the chip carrier 2 and a vertical wall portion 8b for holding the lens tube 7 in a direction orthogonal to the flat portion are integrally formed. A metal plate 9 having good weldability is attached to the vertical wall portion 8b, and the lens cylinder 7 is moved in the optical axis direction and in the direction of direct light with the optical axis in the through hole 8c formed in the vertical wall 8b. The position is adjusted while monitoring the optical power and fixed by welding.
JP 9-33761 A JP 2001-124963 A

In the case of the optical module shown in FIG. 5A, when the lens holder 4 is moved on the slope of the wedge-shaped pedestal 6 in order to adjust the height position of the lens 3, the position of the lens 3 in the plane also changes. Therefore, it is necessary to readjust the position in the plane. For this reason, both the lens holder 4 and the wedge-shaped pedestal 6 are gripped and adjusted, which is problematic in terms of workability.
In addition, in an automated facility, a component having an inclined structure such as a wedge shape is difficult to be chucked or gripped by a collet, and handling for joining the lens holder 4 on the slope of the base 6 is not easy. Further, when the lens holder 4 is fixed on the slope of the pedestal 6, the lens holder 4 may slide along the slope due to the force or gravity that is pressed from above, thereby causing a positional shift.

On the other hand, in the case of the light emitting module shown in FIG. 5B, only the lens cylinder 7 is gripped and alignment is performed in the direction along the vertical direction perpendicular to the optical axis direction. ) Can be solved. However, the lens barrel 7 must be aligned and fixed to the vertical wall 8b of the holding block 8 by welding at a plurality of locations from different directions, and an L-shaped holding block having a vertical wall is required. Therefore, there are problems in productivity and cost.
The present invention has been made in view of the above-described circumstances, and can easily align the lens including the height position from the mounting surface of the base stand, and can be realized with good workability and low cost. An object is to provide an optical module capable of performing the above.

An optical module according to the present invention includes a light emitting element, an optical system including a lens for causing light emitted from the light emitting element to enter an optical fiber, a lens holding member that positions and holds the lens, and a base base on which these are mounted. The lens holding member is provided with a step-like lens holding surface in which the height positions from the base stand are sequentially changed. The lens is held by the selected lens holding surface so that the light emitted from the light emitting element is incident on the optical fiber with an optical coupling rate equal to or higher than a predetermined value.
The optical system includes a collimator lens and a condenser lens, and the condenser lens is held by a lens holding member. Moreover, you may make it the emitted light of a light emitting element be radiate | emitted to an optical fiber through a fiber stub.

  According to the present invention, after selecting the lens holding surface at the optimum height position from the plurality of lens holding surfaces formed in a step shape, the lens is aligned within the plane of the selected lens holding surface. The position adjustment after moving is only within the plane of the lens holding surface. For this reason, position adjustment is easy and productivity can be improved, and a high optical coupling rate can be obtained.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a diagram illustrating an outline of an optical module of the present invention, and FIG. 1B is a diagram illustrating an example of a lens holding member in the present invention. In the figure, 10 is an optical module, 11 is an optical package, 11a is a light transmitting hole, 11b is a lead terminal, 12 is a mount member, 13 is a lens member, 14 is a base base, 14a is a mounting surface, 15 is a lens holding member, Reference numerals 15a to 15e denote lens holding surfaces, 16 denotes a ferrule holder, 17 denotes a ferrule, and 18 denotes an optical fiber cord.

  The optical module 10 according to the present invention is formed, for example, in a form as shown as an example in FIG. The optical module 10 includes an optical package 11 in which a light-emitting element that is a signal light source, a drive circuit for the light-emitting element, and the like are housed, and an optical system that includes a lens member that collects signal light from the package. The ferrule holder 16 and the like for allowing the signal light to enter the optical fiber cord 18 are mounted on the base table 14. In addition, the ferrule 17 attached to end parts, such as the optical fiber cord 18, is inserted in the ferrule holder 16, and the incident signal light is transmitted to an external communication device (not shown).

The optical package 11 includes a light transmitting hole 11a that transmits signal light emitted from the light emitting element in the housing, a lead terminal 11b that supplies a control signal, power, and the like to the drive circuit of the light emitting element, and a mount member that is mounted on the base table 14. 12 etc.
The lens member 13 is configured by collecting a signal light that is transmitted through the light transmitting hole 11a of the optical package 11 and is emitted and that is incident on the optical fiber with a high coupling ratio in a lens housing or the like. The ferrule holder 16 that couples the ferrule 17 of the optical fiber cord 18 can be configured to be integrally coupled to the rear surface side in advance.

  When mounting the lens member 13 on the base base 14, a lens holding member 15 for position adjustment is used in order to optimally set the positional relationship with the light emitting element that is a signal light source. In the present invention, the lens holding member 15 has a step-like lens holding surface 15a to 15a, each having a height position (thickness) from a flat opposite surface (lower surface side) sequentially changed to one surface (upper surface side). The shape with 15e is used. The lens holding member 15 has a flat lower surface fixed to the flat mounting surface 14a of the base base 14 by an adhesive or welding, and is selected from a plurality of lens holding surfaces 15a to 15e formed in a step shape. The holding surface is selected and the lens member 13 is placed and positioned.

  The width W of each of the lens holding surfaces 15a to 15e is desirably formed so as to allow the lens member 13 to be stably placed, and may be at least 1/2 of the housing width of the lens member 13. preferable. Further, the step T of the lens holding surface is preferably in a range in which a decrease in optical coupling rate due to the amount of axial deviation described later is within 2% of the optimum value, for example, within ± 50 μm, and the step T ≦ 50 μm. Is preferred.

  The number of steps on the lens holding surface can be set arbitrarily in consideration of the manufacturing accuracy and assembly accuracy of each component, and the optical coupling rate is set to a predetermined value based on the coupling characteristics between the axial displacement of the condensing lens and the optical power. What is necessary is just to set it as the number of divisions that can be made. In FIG. 1B, the number of stages is five, and the amount of shaft misalignment for 250 μm can be adjusted. The lens holding member 15 can be formed of various materials such as metal, ceramic, and resin.

2A and 2B are diagrams for explaining the position adjustment of the lens member. FIG. 2A is a diagram viewed from the side surface direction, and FIG. 2B is a diagram viewed from the top surface direction. The reference numerals in the figure are the same as those used in FIG. In FIG. 2, the optical package is shown with the housing removed, and the light emitting element 1 in the optical package and the drive circuit component of the light emitting element are formed of a material having good thermal conductivity or the like. 12 is mounted on a base table 14 via 12.
When adjusting the position of the lens member 13, the emitted light from the light emitting element 1 can be monitored using an optical fiber cord 18 with an optical power meter or the like.

  As shown in FIG. 2A, the position of the lens member 13 in the Y direction (that is, the height position of the lens 3 from the mounting surface 14a of the base 14) is adjusted in a stepped shape of the lens holding member 15. Since it is uniquely determined by selecting one of the plurality of lens holding surfaces, it can be easily performed. As described with reference to FIG. 1B, if one step is 50 μm, the adjustment amount (Δy) is in units of 50 μm. Further, it is desirable that the adjustment in the Y direction is performed prior to the adjustment in the X direction.

When the lens holding surface of the lens holding member 15 is selected and the height position of the lens member 13 is determined, as shown in FIG. 2B, the position of the lens member in the X direction (in the horizontal direction orthogonal to the optical axis). Position). The adjustment in the X direction can be performed by translating the lens member 13 on the selected lens holding surface of the lens holding member 15 in the X direction using the step portion of the lens holding surface as a guide.
The adjustment in the two directions of XY orthogonal to the optical axis is performed using the step of the lens holding surface formed in the step shape of the lens holding member 15 as described above, and therefore the adjustment work is relatively easy. Productivity can be increased and a high optical coupling rate can be obtained.

  When adjustment in the Z direction parallel to the optical axis direction is necessary, the lens holding member 15 can be adjusted by moving the mounting surface 14 a of the base table 14. The adjustment in the Z direction may be performed after the adjustment in the two directions of XY. However, the adjustment is performed in advance prior to the selection of the Y direction, and the lens holding member 15 is temporarily held on the base table 14 in the two directions of XY. May be adjusted.

  FIGS. 3A and 3B are diagrams illustrating another embodiment, and are an example including an optical system including two lenses, a collimating lens and a condenser lens. By making the signal light into parallel light by the collimator lens, when the parallel light is condensed by the condensing lens and is incident on the optical fiber, the condensing lens can be hardly affected by the distance from the light source.

  For example, when collimated light from the collimating lens 3 ′ is collected by the lens 3 and is incident on the core of the optical fiber, as shown in FIG. It is assumed that the position is shifted and an axial deviation occurs in the coupling with the optical fiber. Therefore, it is assumed that the position of the lens member 13 on the lens holding member 15 is adjusted to a low position as shown in FIG. In this case, although the distance between the light-emitting element 1 and the lens member 13 also changes, the light received by the lens 3 is converted into parallel light by the collimating lens 3 ′, so that it is not necessary to readjust the distance.

  For this reason, the adjustment in the Z direction described in FIG. 2 can be omitted. Therefore, the lens holding member 15 is fixed at a predetermined position of the base base 14, and thereafter, the adjustment in the Y direction and the adjustment in the X direction shown in FIG. 2 are performed. In this case, since the lens member is moved with respect to the fixed lens holding member 15, the position can be easily adjusted, and the productivity can be further improved.

  FIG. 4 is a diagram showing the relationship between the amount of axial misalignment of the condenser lens and the coupling ratio of optical power. As shown in this figure, when the amount of axial deviation increases from the optimum position of the condensing lens (axial deviation is zero), the optical coupling ratio ΔP (%) decreases in a quadratic function manner. However, when the amount of axial misalignment is ± 100 μm, the optical coupling rate decreases by 12%. However, if the amount of axial deviation is within a range of ± 50 μm, the optical coupling rate can be suppressed to 2% or less. Depending on the specifications of the optical module, the optical coupling rate is generally acceptable if it is 2% or less. Therefore, in order to set the range of the axial deviation to be ± 50 μm or less, one step of the stepped lens holding surface of the lens holding member 15 may be set to 50 μm or less.

  Further, the signal light collected by the condenser lens may be directly incident on the optical fiber of the ferrule inserted into the ferrule holder. For example, as shown in FIG. The light may be incident on the optical fiber via a fiber stub 19 that holds a short optical fiber in the center. In the latter case, the positional relationship between the condenser lens 3 and the stub 19 is fixed and constant, and dust or the like does not enter between them, so that stable characteristics can be maintained.

It is a figure explaining the outline of the optical module by this invention. It is a figure explaining the position adjustment of the lens member of the optical module by this invention. It is a figure explaining other embodiment of this invention. It is a figure which shows the relationship between the position shift of a condensing lens, and an optical coupling factor. It is a figure explaining the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light emitting element, 3 ... Lens, 3 '... Collimating lens, 10 ... Optical module, 11 ... Optical package, 11a ... Translucent hole, 11b ... Lead terminal, 12 ... Mount member, 13 ... Lens member, 14 ... Base stand 14a ... mounting surface, 15 ... lens holding member, 15a to 15e ... lens holding surface, 16 ... ferrule holder, 17 ... ferrule, 18 ... optical fiber, 19 ... fiber stub.

Claims (4)

An optical module comprising: a light-emitting element; an optical system including a lens for causing light emitted from the light-emitting element to enter an optical fiber; a lens holding member that positions and holds the lens; and a base base on which these are mounted. There,
The optical module, wherein the lens holding member includes a step-like lens holding surface in which height positions from the base table are sequentially changed.   2. The lens according to claim 1, wherein the lens is held by a selected lens holding surface so that light emitted from the light emitting element is incident on the optical fiber with a coupling ratio equal to or higher than a predetermined value. Optical module.   The optical module according to claim 1, wherein the optical system includes a collimator lens and a condenser lens, and the condenser lens is held by the lens holding member.   4. The optical module according to claim 1, wherein the light emitted from the light emitting element is incident on an optical fiber through a fiber stub. 5.

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