JPH04326310A - Light emitting module and its manufacture - Google Patents

Abstract

PURPOSE:To execute the optical coupling adjustment only once. CONSTITUTION:A light emitting element package 1 contains a light emitting element such as a laser diode, etc., and a lens for converging a light beam 10 emitted from the light emitting element, and a cylindrical stem holder is fixed to a base 14. The outside of a cylindrical ferrule 4 into which an optical fiber 7 is inserted is connected and fixed to the outside of the stem holder 2 through an elastic body 3 such as a split sleeve, etc. The stem holder 2 is fixed to the base 14 so that the center axis of its outside periphery is positioned on the center line 6 of the light beam 10. In the ferrule 4, the center axis of its outside periphery coincides with the center of the optical fiber 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting module used in optical fiber communication equipment and the like.

0002

2. Description of the Related Art Conventionally, this type of light emitting module has a structure in which there are many adjustment points, as shown in the cross-sectional view of FIG. 4, due to poor mounting accuracy of the light emitting element in the package. That is, first, the central axis of the light beam 25 from the light emitting element package 20 including the light emitting element is the stem central axis 30 of the light emitting element package 20 (the stem central axis 30 is the axis in the direction in which light is emitted from the light emitting element package 20). Adjust the lens holder 22 that fixes the spherical lens 27 in a direction perpendicular to the stem central axis 30 so that it is parallel to the axis of rotational symmetry assuming an ideal rotationally symmetrical shape. do. Then, in this state, the lens holder 22 and the light emitting element package 20 are fixed at the welding portion 28a. Thereafter, the stem holder 21 is fixed to the light emitting element package 20, and then the ferrule 24, into which the optical fiber 29 is inserted, is inserted into the support 23. Furthermore, a light emitting element package 20
The distance between the light emitting device package 20 and the optical fiber 29 and the distance between the optical fiber 29 and the stem central axis 20 are determined so that the coupling efficiency of the light emitting device light output from the light emitting device to the optical fiber 29 is maximized.
The ferrule 24 is fixed to the support 23 at the welded portion 28b. Finally, the support 23 to which the ferrule 24 is fixed is adjusted in the vertical direction with respect to the stem center axis 30, and the support 23 and stem holder 21 are similarly placed at the welded part 28c at a position where the coupling efficiency of the light output is maximized. Fix it.

0003

[Problems to be Solved by the Invention] In the conventional light emitting module described above, in order to maximize the efficiency of optical coupling from the light emitting element package to the optical fiber, firstly, the light beam is perpendicular to the central axis of the stem by using a ball lens. Second, it is necessary to adjust the distance between the optical fiber and the light emitting device package, and third, it is necessary to adjust the angle between the central axis of the optical fiber and the central axis of the stem. Ta. Furthermore, since the ball lens is fixed to the light emitting element package, a special package for the light emitting element must be used. Therefore, adjusting the optical system requires a lot of time, precise adjustment equipment, and
This method requires a special package, is expensive, and has poor productivity.

0004

[Means for Solving the Problems] A light emitting module of the present invention includes a light emitting element package incorporating a light emitting element and a lens for converging a light beam emitted by the light emitting element, and a cylindrical cylinder fixed to the base of the light emitting element package. a cylindrical ferrule into which an optical fiber for coupling with the converged light beam is inserted and having an outer circumference approximately the same diameter as the outer circumference of the stem holder; and a cylindrical ferrule disposed in contact with the outer circumference of the stem holder and the outer circumference of the ferrule. and an elastic body that connects and fixes the stem holder and the ferrule, the stem holder is fixed to the base such that the center axis of the outer periphery is located on the center line of the light beam, and the ferrule is fixed to the base such that the center axis of the outer periphery is located on the center line of the light beam. The axis coincides with the central axis of the optical fiber.

[0005] Such a light-emitting module also includes a first step of fixing a cylindrical stem holder to the base of a light-emitting element package that includes a light-emitting element and a lens that converges a light beam emitted by the light-emitting element; A second step of processing the outer periphery of the stem holder so that the central axis of the outer periphery of the stem holder matches the center line of the optical beam, and the central axis of the outer periphery matches the central axis of the inserted optical fiber. and a third step of fixing the ferrule, the processed stem holder, the outer periphery of the stem holder, and an elastic body disposed in contact with the outer periphery of the ferrule to each other after adjusting the distance between the ferrule and the stem holder.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a light emitting module according to an embodiment of the present invention.

First, the structure of this light emitting module will be explained.

The lens-equipped light emitting element package 1 has a built-in semiconductor laser as a light emitting element, and the emitted light beam 10 is focused onto the light beam center line 6 by the built-in lens. A cylindrical stem holder 2 is fixed to the base 14 of the light emitting element package 1 at a welded portion 5a. On the other hand, the cylindrical ferrule 4 is inserted such that the center of the optical fiber 7 (optical fiber center 11) coincides with the outer circumferential center of the ferrule 4. Further, the outer periphery of the ferrule 4 is fixed to the cylindrical elastic body 3 at a welded portion 5b. The inner periphery of the elastic body 3 is also placed on the outer periphery of the stem holder 2, and is connected and fixed thereto at the welded portion 5c. As the elastic body 3, a split sleeve is used, for example. Furthermore, the outer peripheries of the stem holder 2 and the ferrule 4 have approximately the same dimensions. In this structure,
A light beam 10 emitted from the light emitting device package 1 is coupled to the optical fiber 7 held by the ferrule 4 at the optical fiber center 11. Here, the center axis of the outer periphery of the stem holder 2 is the center of the light beam 10 (light beam center line 6
) is fixed to the base 14 so as to be located above the base 14. Further, the central axis of the outer periphery of the ferrule 4 coincides with the central axis of the optical fiber 7. Note that the welded portions 5a to 5c can be fixed by resistance welding or YAG welding.

Next, details of the structure of this light emitting module will be explained.

A light beam focus 9 coincides with a point on the central axis of the outer periphery of the thin portion 2a of the stem holder 2 on the order of micrometers. Similarly, the outer circumferential center of the ferrule 4 coincides with the inserted optical fiber center 11 on the order of microns, and the thin part 2a of the stem holder 2
The outer circumference of the ferrule 4 also matches on the order of microns. In FIG. 1, the split sleeve used as the elastic body 3 has a structure in which slits are cut in the longitudinal direction of a cylindrical member, so that the inner circumference is slightly elastically deformed. By fitting the stem holder 2 and the ferrule 4 on the inner periphery of the elastic body 3, optical alignment for coupling the light beam 10 from the lens-attached light emitting element package 1 and the optical fiber 7 is made possible. . When a split sleeve is used as the elastic body 3, the inner circumference of the elastic body 3 is elastically deformed to either the outer circumference of the thin part 2a of the stem holder 2 or the outer circumference of the ferrule 4, whichever has a slightly larger diameter, and the stem holder 2 and the ferrule 4 are When compared, the eccentricity of the center positions of both will not be the sum of the manufacturing errors of both, but only the error of one of them.

Next, the manufacturing method of the embodiment shown in FIG. 1 will be described with reference to the light emitting module assembly process diagram shown in FIG. First, as shown in FIG. 2(a), the unprocessed stem holder 2 is fixed to the base 14 of the light emitting element package 1 with a lens using resistance welding. At this time, the light beam focus 9 on the light beam center line 6 is not necessarily on the center axis 12 of the stem holder 2. Next, as shown in FIG. 2(b), the outer periphery 2b of the stem holder 2 is cut so that the light beam focus 9 is located on the central axis of the outer periphery 2b. This cutting can be easily realized using the same method as the centering process currently used in processing optical connectors. Finally, as shown in FIG. 2(c), the stem holder 2 and the ferrule 4 are coupled via the elastic body 3 using a split sleeve, and the light emitted from the light emitting element package 1 is coupled to the optical fiber 7. Elastic body 3 of stem holder 2 at the optimal distance position
, the elastic body 3 and the ferrule 4 are connected to welded parts 5b and 5c, respectively.
Welding is completed using a YAG laser beam. At this time, the light beam focus 9 is on the center axis of the outer circumference of the stem holder 2 after cutting the outer circumference, and the outer circumference of the ferrule 4 and the center of the optical fiber 7 inserted therein are also centered, so the ferrule 4 The light output emitted from the light emitting element package 1 can be easily coupled to the optical fiber 7 by simply sliding it in the direction of the stem central axis 12 on the inner periphery of the elastic body 3.
This can be achieved with high efficiency.

Next, referring to the tolerance diagram of coupling efficiency with respect to displacement and angular deviation of the optical coupling system shown in FIG.
The deviation of the light emitting module structure of the embodiment from the optimum state will be described. In cutting the outer periphery of the stem holder 2, it is possible to suppress the manufacturing error in the diameter of the outer periphery to ±0.5 μm or less and the eccentricity of the light beam focus 9 with respect to the central axis of the outer periphery of the stem holder 2 to 1 μm or less, based on the experience of optical connectors. Similarly, the manufacturing error in the outer diameter of ferrule 4 is ±0.5 μm or less.
Regarding the centering of the optical fiber 7, the amount of eccentricity can be 1 μm or less. When a split sleeve is used as the elastic body 3, the amount of axial deviation Δx between the optical beam center line 6 and the optical fiber center 11
is 2.5 μm at maximum. As shown in FIG. 3(a), the amount of deterioration in coupling efficiency due to this axis misalignment is such that the loss increases by 0.
It becomes 7dB. Since the angular deviation Δθ between the light beam center line 6 from the light emitting element package with lens 1 and the stem center axis 12 can be suppressed within ±2°, from FIG. 3(b), the amount of coupling loss deterioration due to the angular deviation is It can be seen that it is 0.1 dB or less. Further, the distance in the direction of the stem center axis 12 can be adjusted by ±50 μm, and the amount of coupling loss deterioration at this time is within 0.1 dB. Therefore, the structure of the light emitting module of the embodiment shown in FIG. 1 has a maximum deviation of 1 from the optimal coupling state.
It is possible to suppress it within dB.

[0014]

As explained above, the present invention cuts the outer periphery of the stem holder so that the focal position of the light beam from the light emitting element package integrated with the lens is at the center of the outer periphery of the stem holder. An elastic body and a ferrule with a centered optical fiber are used, and optical coupling adjustment is achieved by simply sliding the ferrule in one direction along the optical axis. Therefore, an inexpensive commercial product can be used as the light emitting element package with lens, and the optical axis adjustment can be performed in one dimension (
Since the method only requires adjustment (in the optical axis direction), it is suitable for automated lines, and has the effect of providing a light emitting module that is inexpensive and has excellent productivity.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a light emitting module according to an embodiment of the present invention.

FIG. 2 is an assembly process diagram of the light emitting module according to the embodiment of FIG. 1;

FIG. 3 is a tolerance diagram of coupling efficiency with respect to displacement and angular deviation of the optical coupling system.

FIG. 4 is a sectional view of a conventional light emitting module.

[Explanation of symbols]

1 Light emitting element package with lens 2, 2a, 2b
Stem holder 3 Elastic body 4 Ferrules 5a, 5b, 5c Welding part 6 Light beam center line 7 Optical fiber 9 Light beam focal point 11 Optical fiber center 12 Stem center axis 14 Base 20 Light emitting element package 21 Stem holder 22 Lens holder 23 Support 24 Ferrule 25 Light Beam 27 Ball lenses 28a, 28b, 28c Welding section 29 Optical fiber 30 Stem center axis

Claims (5)

[Claims] 1. A light emitting element package including a light emitting element and a lens for converging a light beam emitted by the light emitting element, a cylindrical stem holder fixed to a base of the light emitting element package, and the focused light beam. a cylindrical ferrule into which an optical fiber to be coupled is inserted and has an outer periphery having approximately the same diameter as the outer periphery of the stem holder, and a cylindrical ferrule arranged in contact with the outer periphery of the stem holder and the outer periphery of the ferrule to connect and fix the stem holder and the ferrule. the stem holder is fixed to the base so that the central axis of the outer periphery is located on the center line of the optical beam, and the ferrule has a central axis of the outer periphery that is aligned with the central axis of the optical fiber. A light-emitting module characterized by: 2. The light emitting module according to claim 1, wherein the elastic body is a split sleeve in which a slit is cut in the longitudinal direction of a cylindrical member. 3. The light emitting module according to claim 1, wherein the light emitting element is a laser diode. 4. The light emitting module according to claim 1, wherein a difference between an outer diameter of the stem holder and an outer diameter of the ferrule is 1 micrometer or less. 5. A first step of fixing a cylindrical stem holder to a base of a light emitting element package that includes a light emitting element and a lens that converges a light beam emitted by the light emitting element, and fixing an outer periphery of the fixed stem holder. a second step of processing the stem holder so that the central axis of its outer periphery coincides with the center line of the optical beam; and a ferrule whose central axis of the outer periphery coincides with the central axis of the inserted optical fiber; A third step of fixing a stem holder and an elastic body disposed in contact with the outer periphery of the stem holder and the outer periphery of the ferrule to each other after adjusting the distance between the ferrule and the stem holder. Production method.