JP2016126034A - Lens holder and optical communication module including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a lens holder capable of preventing a deviation amount in which the center of a lens portion deviates from the optical axis of an optical element due to a change in environmental temperature being out of a permissible range in a configuration capable of optical axis alignment; and an optical communication module comprising the lens holder.SOLUTION: An optical communication module 1 comprises: a substrate 2; a light-emitting element array 3 mounted on the substrate 2; a lens block 4 including a lens portion array 40 comprising a plurality of lens portions 40a optically coupling with respective optical elements of the light-emitting element array 3; and a lens holder 5 including a press-in portion 5a where the lens block 4 is pressed in, and a mounting surface 5b which is mounted on the substrate 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens holder and an optical communication module including the lens holder.

  Conventionally, an optical connector assembled at the tip of an optical fiber wired along this substrate is fixed to a substrate on which an optical element such as a light emitting element or a light receiving element is mounted so as to be optically connected to the optical element. An optical communication module has been proposed (see, for example, Patent Document 1).

  This optical communication module is mounted on a circuit board and has a rectangular parallelepiped photoelectric conversion module having an optical input / output end (optical element) on the upper surface, a metal having a holding plate and four elastic pieces attached to the photoelectric conversion module, or A member holder made of resin and an optical path conversion member positioned and held by four elastic pieces of the member holder are provided.

  The optical path conversion member of the optical communication module includes an optical fiber insertion hole into which an optical fiber is inserted, a reflection surface that converts the optical path, and a lens unit that is optically coupled to the optical element, and is integrally formed of resin.

Japanese Patent No. 4903120

  However, in the conventional optical communication module, the center of the lens unit is positioned on the optical axis of the optical element by manufacturing the photoelectric conversion module and the member holder with high accuracy. In such a case, the center of the lens unit may deviate from the optical axis of the optical element, and the deviation amount may be out of the allowable range. On the other hand, in the method of adhering the lens block to the lens holder with an adhesive, aligning the center of the lens portion of the lens block with the optical axis of the optical element on the substrate (optical axis alignment), and adhering the lens holder to the substrate, There is a possibility that the center of the lens portion is shifted from the optical axis of the optical element due to curing shrinkage or thermal expansion of the adhesive, and the shift amount is out of the allowable range.

  Therefore, an object of the present invention is to suppress the deviation of the center of the lens unit from the optical axis of the optical element and the deviation from the allowable range even when the environmental temperature changes in a configuration capable of optical axis alignment. Another object of the present invention is to provide a lens holder and an optical communication module including the lens holder.

  In order to solve the above-described object, the present invention provides a press-fit portion into which a lens block having a lens portion optically coupled to an optical element mounted on a substrate is press-fitted, and a mounting surface mounted on the substrate. Provided is a lens holder.

  The lens holder is preferably formed of a material having a smaller coefficient of thermal expansion than the material constituting the lens block.

  The lens block has a substantially rectangular parallelepiped shape, an optical fiber insertion hole, an optical path conversion surface that changes an optical path between the optical fiber inserted into the optical fiber insertion hole and the lens unit, and the optical fiber insertion It may include a surface on which a hole is formed and a pair of side surfaces perpendicular to the surface on which the lens portion is formed. In this case, it is preferable that the press-fitting portion of the lens holder has a pair of opposed surfaces that come into contact with the pair of side surfaces of the lens block. The press-fitting portion may further include a surface that contacts a surface opposite to the surface on which the optical fiber insertion hole of the lens block is formed.

  In order to solve the above-described object, the present invention includes a substrate, an optical element mounted on the substrate, a lens block having a lens portion optically coupled to the optical element, and the lens block press-fitted. And a lens holder having a mounting surface mounted on the substrate.

  According to the present invention, in a configuration in which the optical axis can be aligned, it is possible to prevent the center of the lens unit from being displaced from the optical axis of the optical element and the deviation amount from being out of the allowable range even when the environmental temperature is changed. it can.

1A and 1B show a schematic configuration example of an optical communication module according to an embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 shows an example of a lens block according to the present embodiment, in which (a) is a perspective view and (b) is a bottom view. FIG. 3 is a perspective view showing an example of a lens holder according to the present embodiment. 4A and 4B are cross-sectional views for explaining an example of an assembling method of the optical communication module according to the present embodiment. FIGS. 5A to 5C are perspective views showing modifications of the lens holder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, about the component which has the substantially same function, the same code | symbol is attached | subjected and the duplicate description is abbreviate | omitted.

[Embodiment]
1A and 1B show a schematic configuration example of an optical communication module according to an embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA in FIG.

(Overall configuration of optical communication module)
As shown in FIG. 1, the optical communication module 1 includes a substrate 2, a light emitting element array 3 mounted on the substrate 2, and a plurality of lens portions 40 a that are optically coupled to each optical element of the light emitting element array 3. A lens block 4 having a lens section array 40, a press-fit section 5 a into which the lens block 4 is press-fitted, a lens holder 5 having a mounting surface 5 b mounted on the substrate 2, and a plurality of optical fiber insertions of the lens block 4. A plurality of optical fibers 6 inserted into the holes 41 and a driver IC 7 for driving the light emitting element array 3 are provided.

(Substrate structure)
The board | substrate 2 has the upper surface 2a and the lower surface 2b, for example, is formed from insulating materials, such as a glass epoxy resin. The substrate 2 may be a rigid substrate or a flexible substrate, or may be a multilayer substrate in which a plurality of layers are stacked.

(Configuration of light emitting element array)
The light emitting element array 3 includes a plurality (eight in this embodiment) of light emitting elements arranged in an array and transmitting an optical signal. Examples of the light emitting element include a semiconductor laser element such as a VCSEL (surface emitting laser) and an LED (Light Emitting Diode). The light emitting element is an example of an optical element.

  Note that one light emitting element may be used instead of the light emitting element array 3. Further, a light receiving element array may be used instead of the light emitting element array 3 or together with the light emitting element array 3. The light receiving element array includes a plurality of light receiving elements arranged in an array and receiving an optical signal. Examples of the light receiving element include a photodiode. One light receiving element may be used instead of the light receiving element array. The light receiving element is an example of an optical element.

  The optical fiber 6 includes a core and a clad formed around the core. The optical fiber 6 may have a coating layer around the cladding. In this case, it may be inserted into the optical fiber insertion hole 41 while having the coating layer, or the coating layer on the tip side may be peeled off and inserted into the optical fiber insertion hole 41.

(Configuration of driver IC)
The driver IC 7 drives the light emitting element array 3 based on a control signal from a CPU (not shown), and outputs an optical signal from the light emitting element array 3.

(Lens block configuration)
FIG. 2 shows an example of the lens block 4 according to the present embodiment, where (a) is a perspective view and (b) is a bottom view. The lens block 4 has a substantially rectangular parallelepiped shape, and has an upper surface 4a, a lower surface 4b, and side surfaces 4c to 4f. A plurality of optical fiber insertion holes 41 into which the optical fibers 6 are respectively inserted are formed in the side surface 4c. A recess 42 having an optical path conversion surface 42a for converting an optical path between the light emitting element array 3 and the optical fiber 6 is formed on the upper surface 4a. On the lower surface 4b, as shown in FIG. 2B, a lens portion array 40 including a plurality of lens portions 40a is formed. That is, the lens block 4 has a pair of side surfaces 4d and 4f perpendicular to the side surface 4c in which the optical fiber insertion hole 41 is formed and the lower surface 4b in which the lens portion 40a is formed. The plurality of lens portions 40 a are formed at positions facing each light emitting element of the light emitting element array 3 and are optically coupled to each light emitting element.

  The lens block 4 is formed using, for example, an acrylic resin, a polycarbonate resin, a cycloolefin polymer resin, a polyetherimide, or the like as a main material.

(Configuration of lens holder)
FIG. 3 is a perspective view showing an example of the lens holder 5 according to the present embodiment. The lens holder 5 includes a base portion 50 that is bonded and fixed to the upper surface 2 a of the substrate 2, and three wall portions 51 to 53 that rise from the base portion 50. The base portion 50 is formed with an opening 50 a that accommodates the light emitting element array 3. The press-fit portion 5a of the lens holder 5 is configured by the respective inner surfaces 51a, 52a, 53a of the wall portions 51-53. That is, the press-fit portion 5a has inner surfaces 51a and 53a as a pair of opposed surfaces that come into contact with the pair of side surfaces 4d and 4f of the lens block 4.

  The lens holder 5 is made of a material smaller than the thermal expansion coefficient of the lens block 4, for example, a metal. If the material is smaller than the thermal expansion coefficient of the lens block 4, the lens holder 5 may be made of resin.

When the distance between the inner surface 51a of the wall portion 51 and the inner surface 53a of the wall portion 53 is L1, and the distance between the side surface 4d and the side surface 4f of the lens block 4 is L2, the operating temperature range of the optical communication module 1 (For example, 0 ° to 80 °), the following relationship is preferable.
L1 ≦ L2 ≦ (L1 + α)
(Α: intersection of L1 + 20 μm)

(Assembly method)
Next, an example of a method for assembling the optical communication module 1 will be described with reference to FIG. 4A and 4B are cross-sectional views for explaining an example of an assembling method of the optical communication module 1 according to the present embodiment.

  The optical fiber 6 is inserted into the optical fiber insertion hole 41 of the lens block 4 and the optical fiber 6 is fixed to the lens block 4 with an adhesive.

  Next, the lens block 4 to which the optical fiber 6 is fixed is press-fitted into the press-fitting part 5 a of the lens holder 5. Due to the press-fitting of the lens block 4, the side surfaces 4 d to 4 f of the lens block 4 are in contact with the inner surfaces 51 a, 52 a and 53 a of the wall portion 52, and the lower surface 4 b of the lens block 4 is in contact with the inner surface 50 b of the base portion 50. When the lens block 4 is press-fitted, the lens block 4 may be bonded to the lens holder 5 using an adhesive. For example, the lower surface 4b of the lens block 4 and the inner surface 50b of the base portion 50 of the lens holder 5 may be bonded with an adhesive.

  Next, the lens holder 5 into which the lens block 4 is press-fitted is temporarily fixed to the upper surface 2a of the substrate 2 with an ultraviolet curable adhesive.

  Next, a control signal is output from the CPU (not shown) to the driver IC 7, and the light emitting element array 3 is driven by the driver IC 7. The light emitting element array 3 outputs an optical signal, and the lens holder 5 is moved while observing the light quantity of the optical signal through the optical fiber 6 using a light receiver, and the center of the lens portion 40a is set to the optical axis of the light emitting element. Align the optical axis and adjust the light amount. When the position of the lens holder 5 is determined, the ultraviolet curable adhesive is irradiated with ultraviolet rays to cure the ultraviolet curable adhesive, and the lens holder 5 is fixed to the substrate 2.

(Operation and effect of the present embodiment)
According to the present embodiment, the following operations and effects are achieved.
(1) Since the thermal expansion coefficient of the lens block 4 is larger than the thermal expansion coefficient of the lens holder 5, when the environmental temperature rises above room temperature, the lens holder 5 suppresses the expansion of the lens block 4. On the other hand, even if the environmental temperature falls below room temperature and reaches the lower limit value of the operating temperature range, the relationship L1 ≦ L2 is satisfied, so that no gap is generated between the lens block 4 and the lens holder 5. Therefore, in the configuration in which the optical axis can be aligned, it is possible to prevent the center of the lens portion 40a from deviating from the optical axis of the optical element and deviating from the allowable range even if the environmental temperature changes.
(2) A member for fixing the lens block 4 to the lens holder 5 becomes unnecessary, and the number of parts can be reduced.

(Modification)
FIGS. 5A to 5C are perspective views showing modifications of the lens holder 5. 5A to 5C, the arrow indicates the insertion direction of the lens block 4 with respect to the lens holder 5.

  The lens holder 5 shown in FIG. 5A is provided with a pair of wall portions 54 and 55 at positions facing the wall portion 52 with respect to the lens holder 5 shown in FIG. The press-fit portion 5a in this case is constituted by the inner surfaces 51a, 52a, 53a, 54a, and 55a of the wall portions 51 to 55, respectively. By pressing the lens block 4 into the press-fitting portion 5a of the lens holder 5, the side surface 4c of the lens block 4 comes into contact with the inner surfaces 54a and 55a of the pair of wall portions 54 and 55, and the others are the same as in the first embodiment. Similarly, the side surfaces 4d to 4f of the lens block 4 are in contact with the inner surfaces 51a, 52a and 53a of the wall portions 51 to 53, respectively, and the lower surface 4b of the lens block 4 is in contact with the inner surface 50b of the base portion 50.

In the case shown in FIG. 5A, in addition to the configuration of the present embodiment, the distance between the inner surface 52a of the wall portion 52 and the inner surface 54a, 55a of the wall portion 54 and the wall portion 55 is L3, and the lens block 4 When the distance between the side surface 4c and the side surface 4e is L4, it is preferable that the following relationship is satisfied in the operating temperature range (for example, 0 ° to 80 °) of the optical communication module 1.
L3 ≦ L4 ≦ (L3 + β)
(Β: intersection of L3 + 20 μm)

  By defining not only the relationship between L1 and L2 but also the relationship between L3 and L4 as in the present embodiment, not only the direction perpendicular to the direction in which the optical fiber 6 extends but also the lens portion 40a in the direction in which the optical fiber 6 extends. The deviation (optical axis deviation) between the center of the light emitting element and the optical axis of the light emitting element can be suppressed.

  The lens holder 5 shown in FIG. 5B is provided with a ceiling 56 above the lens holder 5 shown in FIG. In this case, the press-fitting portion 5a is configured by the inner surfaces 50b, 51a, 52a, 53a, and 56a of the base portion 50, the wall portions 51 to 53, and the ceiling portion 56, respectively. In this case, it is necessary to form the lens part array 40 so as not to protrude downward from the lower surface 4b. By pressing the lens block 4 into the press-fitting portion 5a of the lens holder 5, the upper surface 4a of the lens block 4 comes into contact with the inner surface 56a of the ceiling portion 56, and the other side surfaces of the lens block 4 are the same as in the present embodiment. 4 d to 4 f are in contact with the inner surfaces 51 a, 52 a and 53 a of the wall portions 51 to 53, respectively, and the lower surface 4 b is in contact with the inner surface 50 b of the base portion 50. The configuration of FIG. 5B can also suppress the optical axis shift of the lens portion 40a.

  The lens holder 5 shown in FIG. 5C is obtained by omitting the base portion 50 from the lens holder 5 shown in FIG. In this case, the press-fitting portion 5a is constituted by the inner surfaces 51a, 52a, 53a, and 56a of the wall portions 51 to 53 and the ceiling portion 56, respectively. By pressing the lens block 4 into the press-fitting portion 5a of the lens holder 5, the upper surface 4a of the lens block 4 comes into contact with the inner surface 56a of the ceiling portion 56, and the other side surfaces of the lens block 4 are the same as in the present embodiment. 4d to 4f are in contact with the inner surfaces 51a, 52a and 53a of the walls 51 to 53, respectively. The configuration of FIG. 5C can also suppress the optical axis shift of the lens portion 40a.

  The embodiments of the present invention are not limited to the above-described embodiments, and various embodiments can be made without departing from the gist of the present invention. For example, in the above embodiment, the driver IC 3 has been described as the electronic component housed on the substrate 2, but a preamplifier IC that amplifies the signal of the light receiving element mounted on the substrate 2 may be used.

  Moreover, you may omit a part of component of embodiment of this invention in the range which does not deviate from the summary of this invention. For example, when the press-fitting portion 5 a of the lens holder 5 is configured by the respective inner surfaces 51 a and 53 a of the pair of wall portions 51 and 53 facing each other, the lens holder 5 may not have the wall portion 52.

DESCRIPTION OF SYMBOLS 1 ... Optical communication module, 2 ... Board | substrate, 2a ... Upper surface, 2b ... Lower surface, 3 ... Light emitting element array,
4 ... lens block, 4a ... upper surface, 4b ... lower surface, 4c-4f ... side surface, 5 ... lens holder,
5a ... press-fitting part, 5b ... mounting surface, 6 ... optical fiber, 7 ... driver IC,
40 ... Lens part array, 40a ... Lens part, 41 ... Optical fiber insertion hole, 42 ... Recessed part,
42a ... Optical path conversion surface, 50 ... Base part, 50a ... Opening part, 51 ... Wall part, 51a ... Inner surface,
52 ... Wall portion, 52a ... Inner surface, 53 ... Wall portion, 53a ... Inner surface, 54 ... Wall portion, 54a ... Inner surface,
55 ... Wall part, 55a ... Inner surface, 56 ... Ceiling part, 56a ... Inner surface

Claims (5)

A press-fit portion into which a lens block having a lens portion optically coupled with an optical element mounted on a substrate is press-fit;
A mounting surface mounted on the substrate;
Lens holder with Formed from a material having a smaller coefficient of thermal expansion than the material constituting the lens block,
The lens holder according to claim 1. The lens block has a substantially rectangular parallelepiped shape, an optical fiber insertion hole, an optical path conversion surface that changes an optical path between the optical fiber inserted into the optical fiber insertion hole and the lens unit, and the optical fiber insertion A surface formed with a hole and a pair of side surfaces perpendicular to the surface formed with the lens part,
The press-fit portion has a pair of opposed surfaces that come into contact with the pair of side surfaces of the lens block.
The lens holder according to claim 1 or 2. The press-fit portion further has a surface that contacts a surface opposite to the surface on which the optical fiber insertion hole of the lens block is formed.
The lens holder according to claim 3. A substrate,
An optical element mounted on the substrate;
A lens block having a lens portion optically coupled to the optical element;
A lens holder having a press-fitting portion into which the lens block is press-fitted, and a mounting surface mounted on the substrate;
Optical communication module with

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