JP4049026B2 - Optical coupling member, optical module and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical coupling member, an optical module, and a manufacturing method thereof used for optical communication.
[0002]
[Prior art]
As a conventional optical module, for example, there is one described in Patent Document 1. The optical module described in this document includes a semiconductor laser, a metal base to which a condensing lens for condensing light from the semiconductor laser is closely fixed, an optical isolator fixed to the metal base, A ferrule fixed to the optical isolator and protecting the optical fiber.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-113931 [0004]
[Problems to be solved by the invention]
However, the above prior art has a structure in which the optical isolator is abutted against and fixed to the tip surface of the metal base to which the condenser lens is closely fixed, so that the position of the optical system in the optical axis direction cannot be adjusted, and the semiconductor laser The focal position of the laser light emitted from the laser beam cannot be adjusted to the optimum position. Further, since it is difficult to adjust the position of the optical isolator around the optical axis (rotation direction), it is difficult to accurately match the polarization direction of the laser light entering the optical isolator. As a result, the optical coupling loss between the optical fiber and the light emitting element increases.
[0005]
An object of the present invention is to provide an optical coupling member, an optical module, and a method for manufacturing the same, which can improve the optical coupling efficiency between an optical fiber and an optical element.
[0006]
[Means for Solving the Problems]
The present invention is an optical coupling member for optically coupling a light emitting element or a light receiving element and an optical fiber, and a first cylindrical fitting into which a tip side portion of a package containing the light emitting element or the light receiving element is fitted. A housing having a joint portion and an isolator disposed inside the housing and configured to remove reflection return of light traveling from the light emitting element to the optical fiber or light traveling from the optical fiber to the light receiving element.
[0007]
For example, when an optical transmission module is configured using such an optical coupling member, an optical transmission unit having a light emitting element and a fiber holding member holding an optical fiber are prepared. The package and the housing of the optical coupling member are fixed in a state where the tip side portion of the package containing the light emitting element in the optical transmission unit is fitted into the first cylindrical fitting portion, and the first cylinder in the optical coupling member is fixed. The fiber holding member is fixed to the housing of the optical coupling member on the opposite side of the shape fitting portion. Since the package containing the light emitting element in this way is configured to be fitted into the first cylindrical fitting portion rather than abutting against the end face of the housing, the package is positioned in the optical axis direction with respect to the optical coupling member. It is possible to adjust. Therefore, when the condensing lens for condensing the light from the light emitting element is provided in the light transmitting unit, the focal position of the light emitted from the light emitting element can be adjusted to the optimum position. In addition, since the position of the rotation direction (around the optical axis) of the package with respect to the optical coupling member can be easily adjusted, the polarization direction of the light entering the isolator can be accurately adjusted. Therefore, the optical coupling efficiency between the light emitting element and the optical fiber can be increased.
[0008]
Preferably, a second cylindrical fitting portion into which the one end side portion of the fiber holding member that holds the optical fiber is fitted is provided on the opposite side of the first cylindrical fitting portion in the housing. The end face of the optical fiber held by the fiber holding member may be obliquely cut to prevent light reflection. In this case, in order to further increase the optical coupling efficiency between the optical element and the optical fiber, it is necessary to adjust the position of the fiber holding member relative to the optical coupling member in the rotational direction (around the optical axis). By providing the housing with the second cylindrical fitting portion into which the side portion is fitted, the position of the fiber holding member in the rotational direction can be easily adjusted.
[0009]
An optical module according to the present invention is interposed between an optical transmitter having a light emitting element, a fiber holding member for holding an optical fiber, an optical transmitter and the fiber holding member, and optically connects the light emitting element and the optical fiber. An optical coupling member for coupling to the light-emitting element, and the optical transmitter further includes a condensing lens that condenses the light emitted from the light-emitting element, and a package that houses the light-emitting element and holds the condensing lens. The optical coupling member includes a housing having a cylindrical fitting portion in which a front end side portion of the package is fitted, and an isolator disposed inside the housing and configured to remove reflection return of light from the light emitting element toward the optical fiber. It is characterized by having.
[0010]
As described above, by providing the housing of the optical coupling member with the cylindrical fitting portion into which the tip side portion of the package containing the light emitting element is fitted, the position of the package is adjusted in the optical axis direction with respect to the optical coupling member. Is possible. Therefore, the focal position of the light emitted from the light emitting element can be adjusted to the optimum position. In addition, since the position of the rotation direction (around the optical axis) of the package with respect to the optical coupling member can be easily adjusted, the polarization direction of the light entering the isolator can be accurately adjusted. Therefore, the optical coupling efficiency between the light emitting element and the optical fiber can be increased.
[0011]
Preferably, the front end of the package is provided with a cylindrical wall portion that extends toward the fiber holding member and has an outer diameter equivalent to the inner diameter of the cylindrical fitting portion. As a result, when the housing of the optical coupling member is fixed to the package by, for example, YAG welding, even if the thickness of the cylindrical fitting portion is reduced to facilitate YAG welding, the condensing lens is mechanically deformed. The load is suppressed.
[0012]
An optical module manufacturing method according to the present invention includes a step of preparing the above-described optical transmission unit, fiber holding member, and optical coupling member, and a state in which the front end portion of the package is fitted into a cylindrical fitting unit. Adjusting the position of the optical coupling member and fixing the package and the housing, and adjusting the position of the optical coupling member and the optical fiber and fixing the housing and the fiber holding member. It is what.
[0013]
In this case, the package is positioned with respect to the optical coupling member in the optical axis direction so that the focal position of the light emitted from the light emitting element becomes a desired position, and the polarization direction of the light entering the isolator is in the desired direction. By adjusting the position of the package in the rotational direction with respect to the optical coupling member, the optical coupling efficiency between the light emitting element and the optical fiber can be increased.
[0014]
An optical module according to the present invention includes a light receiving unit having a light receiving element, a fiber holding member for holding an optical fiber, and a light receiving unit and a fiber holding member. An optical coupling member for optically coupling, and the optical receiver includes a condensing lens that condenses the light emitted from the optical fiber, and a package that houses the light receiving element and holds the condensing lens. The optical coupling member further includes a housing having a cylindrical fitting portion into which a front end side portion of the package is fitted, and an isolator disposed inside the housing to remove reflection return of light from the optical fiber toward the light receiving element. It is characterized by having.
[0015]
Thus, by providing the housing of the optical coupling member with a cylindrical fitting portion into which the tip side portion of the package containing the light receiving element is fitted, the position of the package is adjusted in the optical axis direction with respect to the optical coupling member. Is possible. Therefore, the focal position of the light emitted from the optical fiber can be adjusted to the optimum position. In addition, since the position of the rotation direction (around the optical axis) of the package with respect to the optical coupling member can be easily adjusted, the polarization direction of the light entering the isolator can be accurately adjusted. Therefore, the optical coupling efficiency between the optical fiber and the light receiving element can be increased.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an optical coupling member, an optical module, and a manufacturing method thereof according to the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a cross-sectional view showing a first embodiment of an optical module according to the present invention. In the figure, an optical module 1 of this embodiment is an optical transmission module, and includes an optical transmission unit 2, a receptacle 3, and an optical coupling member 4 interposed between the optical transmission unit 2 and the receptacle 3. Have.
[0018]
The optical transmission unit 2 includes a substantially cylindrical package 7 including a stem 5 and a cap 6, and a plurality of lead pins 8 are fixed to the stem 5. A support base 9 is fixed to the stem 5 in the package 7. A light emitting element 10 that generates laser light and a monitor light receiving element 11 that receives light generated by the light emitting element 10 are placed on the support base 9. The light emitting element 10 is, for example, an InGaAsP-based FP-LD (laser diode), and the monitor light-receiving element 11 is, for example, an InGaAs-based PIN-PD (photodiode).
[0019]
The cap 6 has an opening 6a, and a condensing lens 12 for condensing light from the light emitting element 10 is disposed in the opening 6a. The condensing lens 12 may be a spherical lens as shown or an aspherical lens.
[0020]
The package 7 houses the light emitting element 10 and holds the condenser lens 12. The cap 6 of the package 7 is formed of stainless steel or the like.
[0021]
The receptacle 3 has a single-core ferrule 13 formed of stainless steel or the like, and a fiber stub 14 that is a dummy fiber is inserted into a fiber hole 13 a provided in the single-core ferrule 13. One end surface of the fiber stub 14 substantially coincides with the base end surface 13b of the single-core ferrule 13, and is obliquely cut at a predetermined angle (for example, 6 degrees) to prevent reflection of light from the light emitting element 10. . An external optical fiber 15 is inserted into the fiber hole 13 a of the receptacle 3 so as to abut against the fiber stub 14.
[0022]
The optical coupling member 4 is a member for optically coupling the light emitting element 10 of the optical transmitter 2 and the fiber stub 14 of the receptacle 3. The optical coupling member 4 has a sleeve-type housing 16 formed of stainless steel or the like. The housing 16 has a cylindrical fitting portion 17 having an inner diameter equivalent to the outer diameter of the package 7 of the optical transmission unit 2 on one end side. The cylindrical fitting portion 17 includes a tip side portion of the package 7. It is inserted. It is desirable that the tubular fitting portion 17 is formed to be thin in a range in which a desired strength can be ensured so that YAG welding can be easily performed on the package 7. Further, the other end surface of the housing 16 constitutes a contact surface 18 to which the proximal end surface 13b of the ferrule 13 of the receptacle 3 is joined.
[0023]
By providing the cylindrical fitting part 17 for fitting the package 7 in this way, the position of the package 7 can be adjusted with respect to the housing 16 in the axial direction (Z-axis direction in the drawing) of the package 7 (housing 16). it can. Further, it is possible to easily adjust the position of the package 7 around the Z axis (in the illustrated θ rotation direction) with respect to the housing 16. Furthermore, alignment between the package 7 and the housing 16 (alignment of the X axis and Y axis direction perpendicular to the Z axis direction in the drawing) is not required.
[0024]
In the housing 16, an isolator 19 is disposed on the contact surface 18 side. The isolator 19 removes reflection return of light from the light emitting element 10 toward the fiber stub 14. The isolator 19 includes an isolator element 20 formed by arranging a polarizer, a Faraday rotator, and a polarizer in this order from one end side to the other end side of the housing 16, and an annular shape disposed around the isolator element 20. It consists of a magnet 21.
[0025]
When assembling the optical module 1 with the optical transmitter 2, the receptacle 3, and the optical coupling member 4 as described above, first, the front end portion of the package 7 of the optical transmission unit 2 is attached to the cylindrical fitting portion 17 of the optical coupling member 4. Plug in.
[0026]
Then, when the ferrule 13 of the receptacle 3 is abutted against the contact surface 18 of the housing 16 (described later), the package 7 is placed in the Z-axis direction and θ with respect to the housing 16 so that the optical coupling power to the fiber stub 14 is maximized. Adjust the position in the direction of rotation. Specifically, the package 7 is aligned with the housing 16 in the Z-axis direction so that the focal position of the light emitted from the light emitting element 10 matches the inclined surface (light incident surface) of the fiber stub 14. Further, the package 7 is aligned with the housing 16 in the θ rotation direction so that the polarized light is most transmitted when the light from the light emitting element 10 enters the isolator 19. In this state, the housing 16 is fixed to the package 7 by YAG welding or the like.
[0027]
Subsequently, the receptacle 3 is aligned with respect to the optical coupling member 4 in the X-axis and Y-axis directions. Further, since the light incident surface of the fiber stub 14 is obliquely cut as described above, the optical coupling power to the fiber stub 14 also changes depending on the rotational direction position of the fiber stub 14. For this reason, the position of the receptacle 3 is also adjusted with respect to the optical coupling member 4 in the α rotation direction shown in the figure. In this state, the ferrule 13 of the receptacle 3 is fixed to the housing 16 of the optical coupling member 4 by YAG welding or the like.
[0028]
In contrast to the above assembly method, the position of the optical transmitter 2 and the optical coupling member 4 may be adjusted and fixed after the receptacle 3 and the optical coupling member 4 are positioned and fixed. .
[0029]
As described above, in the present embodiment, the cylindrical fitting portion 17 into which the package 7 of the optical transmission unit 2 is fitted is provided in the housing 16 of the optical coupling member 4, and the Z axis direction of the package 7 with respect to the housing 16 is provided. In addition, since the position adjustment in the θ rotation direction can be reliably performed, the optical coupling efficiency between the light emitting element 10 and the fiber stub 14 can be increased.
[0030]
Further, by providing such a cylindrical fitting portion 17, it is possible to easily adjust the position of the package 7 in the θ rotation direction with respect to the housing 16, and it is not necessary to align the optical transmission portion 2 and the optical coupling member 4. Therefore, the labor at the time of manufacturing the optical module can be reduced.
[0031]
Furthermore, since the lens attached to the cap 6 of the optical transmission unit 2 is the condensing lens 12, it is not necessary to provide a condensing lens between the isolator 19 and the fiber stub 14, unlike when a collimating lens is used. . In addition, since the isolator 19 is disposed on the contact surface 18 side of the housing 16 where the light is sufficiently focused by the condenser lens 12, a small and inexpensive isolator 19 can be used. Therefore, the optical coupling member 4 can be reduced in size as a whole, the number of parts required for the optical module 1 can be reduced, and the manufacturing cost can be suppressed.
[0032]
FIG. 2 is a cross-sectional view showing a second embodiment of the optical module according to the present invention. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0033]
In the same figure, the optical module 30 of this embodiment has the optical coupling member 31 instead of the optical coupling member 4 in 1st Embodiment. The optical coupling member 31 has a sleeve type housing 32, and the cylindrical fitting portion 17 is provided on one end side of the housing 32. A cylindrical fitting portion 33 having an inner diameter equivalent to the outer diameter of the receptacle 3 is provided on the other end side of the housing 32, and a proximal end portion of the receptacle 3 is fitted into the cylindrical fitting portion 33. Yes. The housing 32 is fixed to the ferrule 13 of the receptacle 3 by YAG welding or the like in a state where the proximal end surface 13b of the receptacle 3 is abutted against the inner wall surface 32a of the housing 32.
[0034]
By providing the cylindrical fitting portion 33 in the housing 32 as described above, the position of the receptacle 3 in the α rotation direction with respect to the optical coupling member 31 can be easily adjusted, and the alignment operation of the receptacle 3 with respect to the optical coupling member 31 is performed. No need to Thereby, the labor at the time of optical module manufacture can be reduced more. In addition, the optical coupling member 31 and the receptacle 3 can be stably fixed.
[0035]
FIG. 3 is a cross-sectional view showing a third embodiment of the optical module according to the present invention. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0036]
In the figure, an optical module 40 of the present embodiment has a cap 41 instead of the cap 6 in the first embodiment. A tube that extends toward the base (receptacle 3 side) of the cylindrical fitting portion 17 of the optical coupling member 4 and has an outer diameter equivalent to the inner diameter of the cylindrical fitting portion 17 at the tip of the cap 41 A shaped wall portion 42 is provided.
[0037]
Even if the thickness of the cylindrical fitting portion 17 is sufficiently thin so that the cylindrical fitting portion 17 is easily YAG welded to the cap 41 by providing such a cylindrical wall portion 42, It is possible to prevent a mechanical load such as distortion from being applied to the optical lens 12.
[0038]
FIG. 4 is a cross-sectional view showing a fourth embodiment of the optical module according to the present invention. In the figure, the same or equivalent members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0039]
In the figure, an optical module 50 of this embodiment is an optical receiver module, and includes a top-incident-type optical receiver 51, and a receptacle 3 and an optical coupling member 4 similar to those of the first embodiment. The optical receiver 51 has a package 54 including a stem 52 and a cap 53, and a plurality of lead pins 55 are fixed to the stem 52. A condensing lens 56 is disposed in the opening 53 a of the cap 53. In the package 54, a support base 57 is disposed on the stem 52, and a light receiving element 58 is placed on the support base 57. The light receiving element 58 is, for example, an InGaAs PIN-PD.
[0040]
In such an optical module 50, the light transmitted from the external optical fiber 15 is emitted from the fiber stub 14 of the receptacle 3. Then, the light enters the light receiving element 58 through the isolator 19 and the condenser lens 56 of the optical coupling member 4. The condensing lens 56 is a lens that condenses the light emitted from the fiber stub 14. The isolator 19 removes reflection return of light from the fiber stub 14 toward the light receiving element 58.
[0041]
In this embodiment, since the position adjustment of the package 54 with respect to the housing 16 of the optical coupling member 4 in the Z-axis direction and the θ rotation direction can be reliably performed, the optical coupling efficiency between the light receiving element 58 and the fiber stub 14 can be increased. It becomes possible.
[0042]
The optical receiver 51 is not limited to the top-incident type as described above, but may be a waveguide type. Further, a cylindrical fitting portion into which the receptacle 3 is fitted may be provided in the housing 16 of the optical coupling member 4 as in the second embodiment, or the package of the optical receiving portion 51 as in the third embodiment. You may provide a cylindrical wall part in the front-end | tip part of 54. FIG.
[0043]
While several preferred embodiments of the optical module according to the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, the receptacle 3 is fixed to one end side of the housing of the optical coupling member. Instead of the receptacle 3, a pigtail provided with an optical connector on one side of the optical fiber cord is used. The pigtail optical connector may be fixed to the optical coupling member.
[0044]
【The invention's effect】
According to the present invention, since the first cylindrical fitting portion into which the front end portion of the package containing the light emitting element or the light receiving element is fitted is provided in the housing of the optical coupling member, the package is placed on the optical axis with respect to the housing. The position can be adjusted in the direction. Thereby, the optical coupling efficiency between the optical fiber and the light emitting element or the light receiving element can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of an optical module according to the present invention.
FIG. 2 is a cross-sectional view showing a second embodiment of an optical module according to the present invention.
FIG. 3 is a cross-sectional view showing a third embodiment of an optical module according to the present invention.
FIG. 4 is a cross-sectional view showing a fourth embodiment of an optical module according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical module, 2 ... Optical transmission part, 3 ... Receptacle, 4 ... Optical coupling member, 7 ... Package, 10 ... Light emitting element, 12 ... Condensing lens, 13 ... Ferrule (fiber holding member), 14 ... Fiber stub ( Optical fiber), 16 ... housing, 17 ... cylindrical fitting part (first cylindrical fitting part), 19 ... isolator, 30 ... optical module, 31 ... optical coupling member, 32 ... housing, 33 ... cylindrical fitting Part (second cylindrical fitting part), 40 ... optical module, 41 ... package, 42 ... cylindrical wall part, 50 ... optical module, 51 ... light receiving part, 54 ... package, 56 ... condensing lens, 58 ... Light receiving element.

Claims (6)

An optical coupling member for optically coupling a light emitting element or a light receiving element and an optical fiber,
A housing having a first cylindrical fitting portion into which a tip side portion of a package containing the light emitting element or the light receiving element is fitted;
An optical coupling member, comprising: an isolator disposed inside the housing and configured to remove a reflection return of light from the light emitting element toward the optical fiber or light from the optical fiber toward the light receiving element. A second cylindrical fitting portion into which one end side portion of a fiber holding member holding the optical fiber is fitted is provided on the opposite side of the first cylindrical fitting portion in the housing. The optical coupling member according to claim 1. An optical transmitter having a light emitting element;
A fiber holding member for holding an optical fiber;
An optical coupling member interposed between the light transmission unit and the fiber holding member for optically coupling the light emitting element and the optical fiber;
The light transmission unit further includes a condenser lens that condenses the light emitted from the light emitting element, and a package that houses the light emitting element and holds the condenser lens,
The optical coupling member is disposed inside the housing having a cylindrical fitting portion into which a front end side portion of the package is fitted, and removes reflection return of light from the light emitting element toward the optical fiber. An optical module comprising an isolator. The cylindrical wall portion having an outer diameter that extends to the fiber holding member side and has an outer diameter equivalent to the inner diameter of the cylindrical fitting portion is provided at the distal end portion of the package. 3. The optical module according to 3. A step of preparing an optical transmitter, a fiber holding member and an optical coupling member according to claim 3 or 4,
A step of adjusting the position of the optical transmitter and the optical coupling member in a state where the distal end portion of the package is fitted into the cylindrical fitting portion, and fixing the package and the housing;
A method of manufacturing an optical module, comprising: adjusting a position of the optical coupling member and the optical fiber, and fixing the housing and the fiber holding member. An optical receiver having a light receiving element;
A fiber holding member for holding an optical fiber;
An optical coupling member interposed between the optical receiver and the fiber holding member, for optically coupling the light receiving element and the optical fiber;
The light receiving unit further includes a condenser lens that condenses the light emitted from the optical fiber, and a package that houses the light receiving element and holds the condenser lens,
The optical coupling member is disposed inside the housing having a cylindrical fitting portion into which a front end portion of the package is fitted, and removes reflection return of light from the optical fiber toward the light receiving element. An optical module comprising an isolator.

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