JP2975813B2 - Optical element module and method of assembling the same - 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 element module having a structure in which an optical element and an optical fiber are coupled by a butt joint system and a method for assembling the same, and more particularly, to easily align an optical axis between the optical element and the optical fiber. And a method for assembling the same. The optical element module of the present invention is used for optical fiber communication, optical fiber gyro, and the like.

[0002]

2. Description of the Related Art An optical element module in which an optical element such as a light-emitting element and a light-receiving element and an optical fiber are fixed at an optically optimum position and integrated is such that light is converged and converged by an optical medium such as a lens. There is a method of directly coupling without using an optical medium, and a method of directly coupling without using an optical medium (referred to as a butt joint or butt coupling method). The former is disclosed in JP-A-4-1011.
No. 08, Japanese Patent Application Laid-Open No. 4-212906, etc., have the feature that light from an optical element can be efficiently incident on an optical fiber. There are drawbacks that it takes a long time and is expensive due to the use of lenses and the like.

[0003] The latter butt-joint method is used when the light intensity of the optical element is large and it is not necessary to increase the coupling efficiency by using a lens, or when the lens is used because of a large exit angle of light from the optical element. This method is often used when the coupling efficiency cannot be improved because of
There was one described in JP-A-35904. The present invention relates to this butt joint system.

The outline of the conventional butt joint system will be described below. FIG. 5 is a sectional view showing the structure of the optical element module. The optical element 5 is mounted on the stem 4 and is electrically connected to an external device (not shown) by the stem 4.
This is performed via the lead terminal 7 provided in the first embodiment. The optical fiber 1 has one end held by a ferrule 2,
It is inserted inside the holder 3. The bare fiber 1 a from which the coating of the optical fiber 1 has been removed protrudes from the tip of the ferrule 2 and is close to the upper part of the optical element 5. The ferrule 2 is fixed to a through hole above the holder 3 by an adhesive 9 and a pair of press-fit members 10. The stem 4 is also fixed to the lower part of the holder 3 by soldering.

The optical element module thus constructed is assembled in the following procedure. One end of the optical fiber 1 on which the bare fiber 1a is already provided is fixed to the ferrule 2. The ferrule 2 is inserted into the through hole above the holder 3, and the amount of projection of the bare fiber 1 a into the holder 3, that is, the optical axis adjustment in the Z-axis direction (the center axis direction of the optical fiber 1) is performed. When adjusting the optical axis, the stem 4 on which the optical element 5 and the lead terminal 7 are mounted in advance is attached to the holder 3.
While monitoring the light emitted from the optical element 5 at the other end of the optical fiber 1 while temporarily mounting the
The distance (c) between the tip of a and the optical element 5 is adjusted to be appropriate.

After the optical axis adjustment is completed, the ferrule 2 and the holder 3 are fixed with an adhesive 9, and further, are firmly fixed with a press-fit member 10. The reason for further fixing with the press-fitting member 10 is to prevent the adhesive 9 from softening due to the heat at the time of soldering in the (next step), and to prevent the optical axis adjustment performed from changing. The stem 4 (the optical element 5 and the lead terminal 7 are fixed in advance) is soldered to the lower part of the holder 3 to hermetically seal the optical element 5.

[0007]

However, the conventional optical element module shown in FIG. 5 has the following problems. (A) When the optical axis adjustment in the Z-axis direction is performed, the distance between the tip of the bare fiber 1a and the optical element 5 ((c) in FIG. 5) is as small as several tens μm, so that it is erroneous during the adjustment. Contact may damage one or both. In addition, the labor of the worker to prevent the damage is great.

(B) Regarding the positional relationship between the optical fiber 1 and the optical element 5, even if the adjustment in the Z-axis direction (the distance between the tip of the bare fiber 1a and the optical element 5) can be performed, the adjustment in the X and Y-axis directions can be performed. Is a difficult structure. Since the coupling efficiency of light with respect to the amount of axis deviation in the X or Y axis direction changes sharply as shown in FIG. 4, it is necessary to easily adjust the optical axis in the X and Y axis directions. SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an optical element module and an assembling method of the optical element module, in which the optical axis adjustment between the optical element and the optical fiber, particularly the adjustment in the Z-axis direction is unnecessary.

[0009]

In order to solve the above problems, in an optical element module according to the present invention, a reference for separating a tip of a ferrule holding an optical fiber from an optical element by a predetermined distance is provided. And a holder whose position can be freely changed with respect to the ferrule and the stem before being fixed.

In the method for assembling an optical element module according to the present invention, the abutting member and the holder are provided, and the end of the ferrule is brought into contact with the upper surface of the abutting member and then separated by a predetermined distance. Positioning the optical fiber in the direction of the central axis thereof, and adjusting the position of the optical fiber with respect to the optical element in a plane perpendicular to the central axis of the optical fiber, the ferrule and the holder, the holder and the stem. Each was fixed.

[0011]

The optical fiber is held by the ferrule such that the tip does not protrude from the tip of the ferrule, and the optical element does not come into contact with the ferrule when the tip of the ferrule comes into contact with the upper surface of the abutting member. So that it is mounted on the stem.

In this state, by positioning the tip of the ferrule and the upper surface of the abutting member at a predetermined distance, the center of the optical fiber is set in the direction of the central axis (hereinafter referred to as the Z-axis direction), and the optical element and the optical element are aligned. Position adjustment (optical axis adjustment) is performed in a plane perpendicular to the central axis of the optical fiber (hereinafter referred to as X and Y axis directions) so that optimum coupling with the fiber is obtained, and the ferrule and the stem are connected via the holder. Fix it. This makes it unnecessary to adjust the optical axis in the Z-axis direction, and also prevents damage to the optical element due to the movement of the ferrule during the position adjustment in the X and Y-axis directions (that is, the optical axis adjustment).

[0013]

FIG. 1 is a sectional view showing the structure of an optical element module according to an embodiment of the present invention. The same components as those in the conventional example are denoted by the same reference numerals, and detailed description of those components will be omitted. The optical element 5 (for example, a laser diode) is located at a position lower than the upper surface of the abutment member 6.
It is mounted on the side. In other words, the butting member 6
Is located above the optical element 5. Specifically, it is fixed at a position such that the distance in FIG. 1A is, for example, 20 μm. The abutting member 6 also serves as a heat sink for the optical element 5.

The butting member 6 is fixed to the stem 4 so that the optical element 5 is located substantially at the center. The optical element 5
The electrical connection between the device and an external device (not shown) is made via a lead terminal 7 provided on the stem 4 as in the conventional example. One end of the optical fiber 1 is held by the ferrule 2, inserted into the holder 3, and is close to the upper surface of the abutting member 6. In this case, the tip of the optical fiber 1 is held by the ferrule 2 so as not to protrude from the tip of the ferrule 2. The ferrule 2 is fixed to a stem 4 via a holder 3.

The optical element module configured as described above is assembled in the following procedure. The butting member 6 on which the optical element 5 is mounted is fixed to the stem 4 in advance so as to have the above-described arrangement. One end of the optical fiber 1 is fixed to the ferrule 2. At this time, the tip of the optical fiber 1 does not protrude from the tip of the ferrule 2. Insert the tip of the ferrule 2 into the upper part of the holder 3,
It abuts on the upper surface of the abutment member 6 (that is, makes contact).

The tip of the ferrule 2 is separated from the upper surface of the abutting member 6 by a predetermined distance by retracting the ferrule 2 by a predetermined distance from the state. Specifically, the distance (b) in FIG. 1 is set to, for example, 20 μm. In addition, the reason for separating by the predetermined distance is that the non-contact makes the movement of the ferrule 2 smooth in the adjustment of the optical axis in the X and Y axis directions, and that the holder 3 and the like due to a temperature change. This is to prevent the optical fiber 1 and the upper surface of the butting member 6 from colliding due to contraction. Such a concept is based on the fact that the light coupling efficiency changes very slowly with respect to the distance in the Z-axis direction as shown in FIG. 3 and that a predetermined degree of coupling is sufficiently obtained.

The optical axis adjustment in the X and Y axis directions is performed while monitoring the light emitted from the optical element 5 at the other end of the optical fiber 1. This optical axis adjustment can be understood from FIG.
Fine adjustment is required. After the optical axis adjustment is completed, the ferrule 2 and the holder 3 are fixed first, and then the holder 3 and the stem 4 are fixed by YAG laser welding or the like. When performing hermetic sealing, an adhesive is applied to a necessary portion after welding.

The positioning in the Z-axis direction in the optical element module configured as described above only requires that the ferrule 2 be once abutted against the abutting member 6 and then retracted by a predetermined distance. It is not necessary to adjust to the optimum state while monitoring the light).

The present invention is not limited to the above embodiment, but may be as follows. A portion corresponding to the holder 3 in FIG. 1 may be divided into a holder 3 and a cap 8 as shown in FIG. In this case, before performing the positioning in the Z-axis direction and the optical axis adjustment in the X and Y-axis directions, the cap 8 is resistance-heated to the stem 4 (the butting member 6 on which the optical element 5 is mounted is fixed in advance). And the holder 3 is mounted on the ferrule 2. In this state, the cap 8 and the stem 4 can be regarded as a stem together.

1 and 2, the optical element 5
Is mounted on the abutment member 6, but may be mounted directly on the stem 4. That is, the heat sink of the optical element 5 is not limited to the butting member 6. Further, the abutment member 6 and the stem 4 are configured separately, but may be integrated.

[0021]

As described above, the optical element module according to the present invention is fixed to the butting member serving as a reference for separating the tip of the ferrule holding the optical fiber and the optical element by a predetermined distance. Before the ferrule and the stem are equipped with a holder whose position can be freely changed,
The optical axis adjustment in the Z-axis direction becomes unnecessary, and the optical axis adjustment in the X- and Y-axis directions can be easily performed. And
Since the adjustment of the optical axis in the Z-axis direction becomes unnecessary, the time required for the optical axis adjustment can be reduced. Further, in the butt joint system, it was possible to prevent the optical element from being damaged during the optical axis adjustment.

Also, in the method for assembling an optical element module according to the present invention, the abutting member and the holder are provided, and the tip of the ferrule is brought into contact with the upper surface of the abutting member and then separated by a predetermined distance. Thereby positioning the optical fiber in the central axis direction (Z-axis direction), and adjusting the position of the optical fiber with respect to the optical element in a plane (X and Y axis directions) perpendicular to the central axis of the optical fiber (optical axis adjustment). ), The same effect as described above was obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of an optical element module according to an embodiment of the present invention;

FIG. 2 is a sectional view of an optical element module according to another embodiment of the present invention;

FIG. 3 is a view showing light coupling efficiency with respect to a distance in a Z-axis direction;

FIG. 4 is a diagram showing light coupling efficiency with respect to an amount of axis shift in the X or Y axis direction;

FIG. 5 is a sectional view showing the structure of a conventional optical element module.

[Explanation of symbols]

1 ... optical fiber, 2 ... ferrule, 3 ... holder
4 ··· stem 5 · · · · optical element 6 · · · butting member 7
··· Lead terminals, 8 ··· caps.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B ⁶ /42-6/43 H01L 31/0232 H01L 33/00

Claims (2)

(57) [Claims] An optical fiber is held so that a stem (4), an optical element (5) mounted on the stem, an optical fiber (1), and a tip of the optical fiber do not protrude from the tip. A ferrule (2) and a holder (3) for fixing the ferrule and fixing to the stem
And an abutment member (6) provided on the stem with its upper surface spaced from the tip of the ferrule, and the upper surface being located above the optical device. Before the holder is fixed to the stem,
The position of the holder is adjustable with respect to the stem in a plane perpendicular to the central axis of the optical fiber, and before the ferrule is fixed to the holder, the ferrule is fixed to the holder. The optical fiber is movable in the central axis direction, and after the tip of the ferrule is brought into contact with the upper surface of the abutting member, the optical fiber can be positioned in the central axis direction by being separated by a predetermined distance. An optical element module comprising: 2. A stem (4), an optical element (5) mounted on the stem, an optical fiber (1), and holding the optical fiber such that the tip of the optical fiber does not protrude from the tip. A ferrule (2) and a holder (3) for fixing the ferrule and fixing to the stem
And an abutment member (6) provided on the stem with its upper surface spaced from the tip of the ferrule and having the upper surface located above the optical element. After the tip of the ferrule is brought into contact with the upper surface of the abutment member, positioning the optical fiber in the central axis direction by separating the optical fiber by a predetermined distance; and Adjusting the position of the optical fiber with respect to the optical element in a vertical plane,
A method for assembling an optical element module, comprising fixing a ferrule and a holder, and a holder and a stem, respectively.