JPH11287932A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of interference due to stray light between adjacent optical elements. SOLUTION: The optical module 21 is structured by integrally fitting a ferrule 2 which contains an optical fiber 7 and has a join end surface 2a at its tip side to an IC package 3 wherein a light emitting element and a light receiving element 6 are arranged side by side. The end surfaces of optical fibers 7 (7A and 7B) face the light emitting element 5 or light receiving element 6. The inside of the IC package 3 is sectioned by a partition member 30 into a space 32a on the side of the light emitting element 5 and a space on the side of the light receiving element 6. Interference due to stray light between the light emitting element 5 and light receiving element 6 is prevented by the partition member 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module serving as an electric / optical interface between an optical fiber and an electronic circuit in an optical communication system.

[0002]

2. Description of the Related Art In an optical communication system, an optical module that couples an optical fiber and an electronic circuit is usually provided with a laser diode (hereinafter abbreviated as LD) or a light emitting diode (hereinafter L).
A light emitting element for transmission such as ED) and a light receiving element such as photodiode (hereinafter abbreviated as PD) are incorporated in the same IC package (case). The mainstream of development is a structure in which an optical connector of a pin-fitting alignment type is integrated with the IC package so that the connection can be performed correctly and easily. The optical connector of the pin-fitting alignment method (often referred to as an MT optical connector) is an optical fiber hole formed in a generally rectangular ferrule made of plastic such as a 12-type optical fiber connector of JIS C5981. After the connector has been inserted and fixed, the joint end surface thereof is polished with, for example, PC. When connecting the connectors, the two optical connectors to be connected are aligned with each other by the guide pins inserted into the guide pin holes of the respective ferrules. .

FIGS. 9 and 10 show an example of such a conventional optical module. In this optical module 1, a ferrule 2 substantially corresponding to the optical connector (MT connector) of the pin-fitting alignment method described above is integrated with an IC package 3, and is made of silicon, ceramics, glass, or the like installed in the IC package 3. This is a structure in which optical elements are arranged on a substrate 4. The optical module 1 in the illustrated example is a case of two cores of reception and transmission.
A light emitting element 5 such as an ED and a light receiving element 6 such as a PD are mounted on mounts 11 and 12 provided separately on the substrate 4. When the light emitting element is an LD, a surface emitting type LD is generally used. The ferrule 2 is used for the MT.
Instead of the connector itself, a MT connector whose flange for positioning is removed by processing after molding is usually used, but as shown in FIGS. 12 and 13, two optical fibers 7 are inserted into the optical fiber holes 2c. The optical fiber 7 is inserted and fixed inside, and has a joint end face 2a on which the front end side is polished with PC or the like, and the other end face of the built-in optical fiber 7 is exposed on the rear end face 2b. Normally, the optical fiber 7 slightly protrudes from the rear end face 2b of the ferrule 2. The ferrule 2 and the light emitting element 5 and the light receiving element 6 are aligned and fixed so that each optical fiber 7 correctly faces the light emitting element 5 or the light receiving element 6, respectively. 2d is a guide pin hole, and 8 is a terminal. Then, as shown in FIG.
When an optical fiber cord 13 having a transmission optical fiber 13a is connected to the optical module 1, a ferrule 2 of the optical module 1 and a structure substantially similar to the ferrule 2 attached to the tip of the optical fiber cord 13 are used. The MT optical connector 14 is connected. The MT connector is
This is an optical connector for a multimode type optical fiber, and the optical fiber 7 of the optical module 1 and the transmission optical fiber 13a connected thereto are also, for example, large-diameter multimode optical fibers.

FIG. 11 shows another conventional optical module 1 ′, in which a light emitting element 5 and a light receiving optical element 6 are provided on the same mount 15 on a substrate 4. Other points are the same as those of the optical module 1 of FIGS.

[0005]

The conventional optical modules 1 and 1 'have the following problems. Fig. 15 (a)
As shown in FIG. 7, the light output of the light emitting element 5 includes light (that is, stray light) other than the light entering the corresponding optical fiber 7 (B), and the stray light is reflected by the rear end face 2b of the ferrule 2, and the reflected light Enter the adjacent light receiving element 6.
In this case, a problem occurs in which the light receiving value of the light receiving element 6 becomes abnormal. Further, as shown in FIG.
The light emitted from the optical fiber 7 (A) on the optical fiber 7 (A) strikes not only the light receiving element 6 but also the light emitting element 5 and is reflected.
A problem occurs that adversely affects light incident on (B).
In addition, the incidence of useless light may cause the light emitting element 5 and the light receiving element 6 to deteriorate. In addition, the light output
Although there are both direct light and light as an electromagnetic wave, since the light emitting element 5 and the light receiving element 6 are arranged close to each other, when communication is performed at a high frequency, as shown in FIG. The light output as an electromagnetic wave from the light emitting element 5 adversely affects the sensitivity of the light receiving element 6.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional disadvantages, and has as its object to provide an optical module in which stray light does not cause interference between a plurality of optical elements installed in close proximity. And

[0007]

According to the present invention, there is provided a ferrule having a plurality of optical fibers therein, a front end side of which is a joint end face for butt connection, and an end face of the optical fiber is exposed at a rear end face. In an optical module in which a plurality of optical elements corresponding to the plurality of optical fibers are arranged side by side and integrally connected so that each optical fiber end face faces each optical element, the inside of the case is It is characterized in that each optical element is partitioned into a plurality of spaces each of which is accommodated.

According to a second aspect of the present invention, in the optical module of the first aspect, a metal or a material containing a metal is used as a partition member for partitioning a space in which each optical element is housed.

[0009]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS. 1 and 2 show an optical module 21 according to a first embodiment. Conventional optical module 1 of FIG.
The same reference numerals are given to the parts common to. In this optical module 21, a ferrule 2 substantially corresponding to an optical connector (MT connector) of a pin-fitting alignment type is formed by a plastic or ceramic IC package (case).
3 and integrated. Two substrates 24 made of silicon, ceramics, glass, or the like are provided in the IC package 3, and mounts 11 and 12 provided on each substrate 24 are provided.
A light emitting element 5 such as an LD or an LED or a light receiving element 6 such as a PD is provided thereon. Optical module 1 in illustrated example
Is a case of two cores of reception and transmission. When the light emitting element is an LD, a surface emitting type LD is generally used. The ferrule 2 is not the MT connector itself,
Normally, an MT connector in which the positioning flange is removed by post-molding processing is used, but the one shown in FIG. 9 has the same structure as the ferrule 2 in FIG. 12 and 13, which are inserted and fixed in 2 c), and are bonded to each other, and the front end side is PC-polished or the like.
The other end face of the built-in optical fiber 7 is exposed at the rear end face 2b. Normally, the optical fiber 7 slightly protrudes from the rear end face 2b of the ferrule 2. The ferrule 2 and the light emitting element 5 and the light receiving element 6 are aligned and fixed so that each optical fiber 7 correctly faces the light emitting element 5 or the light receiving element 6, respectively.
8 is a terminal. The MT connector is an optical connector for a multi-mode optical fiber, and the optical fiber 7 of the optical module 1 is, for example, a large-diameter multi-mode optical fiber.

In the present invention, the inside of the IC package 3 is
Space 32 in which light emitting element 5 is installed by partition member 30
a and a space 32b in which the light receiving element 6 is installed. The partition member 30 is preferably made of a metal plate in order to obtain an action of shielding the electromagnetic wave from the light emitting element 5.
Alternatively, a sufficiently dense metal mesh that does not transmit light may be used.
Further, plastic or ceramic containing metal can also be used. Further, a material obtained by plating or depositing a metal on plastic or ceramic may be used.
In addition, when the electromagnetic wave shielding effect is not particularly problematic, a simple plastic or ceramic may be used.
The partition member 30 may be formed integrally with the IC package 3 or may be formed as a separate member.
It may be attached and fixed to the C package 3 later. When integrated with the IC package 3, it may be formed integrally with the lid 3 a of the IC package 3 or may be formed integrally with the base side of the IC package 3. In addition, when it is fixed later as a separate member, it may be fixed to the lid 3a side or may be fixed to the package body 3b side.

In the above-described optical module 21, since the light emitting element 5 and the light receiving element 6 are isolated from each other by the partition member 30, stray light from the light emitting element 5 (other than light entering the corresponding optical fiber 7 (B)). Light) adjacent to the light receiving element 6
No problem occurs, and no problem occurs that stray light (light other than light entering the light receiving element 6) from the optical fiber 7 (A) on the light receiving element 6 hits the light emitting element 5. Therefore, the problem that noise is generated in the light emitting element 5 and the light receiving element 6 due to the incidence of unnecessary light does not occur.

Further, since the partition member 30 made of a metal plate functions to shield electromagnetic waves, there is no problem that the light output of the light emitting element 5 as the electromagnetic wave adversely affects the sensitivity of the light receiving element 6.

3 to 6 show another embodiment of the present invention.
3 is a plan view of the optical module 31 with the lid removed, FIG. 4 is a cross-sectional view taken along line BB of FIG. 3, FIG. 5 is a cross-sectional view taken along line CC of FIG.
FIG. 4 is a sectional view taken along line D-D of FIG. The optical module 31 of this embodiment has a structure in which two mounts 33 and 34 are directly installed in an IC package 3 and a light emitting element 5 or a light receiving element 6 is provided on each of the mounts 33 and 34. I
The point that the interior of the C package 3 is partitioned by the partition member 30 into a space 32a in which the light emitting element 5 is installed and a space 32b in which the light receiving element 6 is installed is the same as in the embodiment of FIGS. Other structures are the same as those in FIGS.

FIGS. 7 and 8 show an optical module 41 according to still another embodiment. The optical module 41 has four optical elements 42 (two light emitting elements and two light receiving elements) inside an IC package 3 ′. The inside of 3 ′ is partitioned into four spaces 43 for each optical element 42. Each optical element 42 is provided on each mount 44. The ferrule 2 'is basically the same as the ferrule 2 described above, except that the number of optical fibers 7 is four. 2d is a guide pin hole, and 8 is a terminal. As in this embodiment, the present invention can be applied to a case where there are three or more optical elements provided in a case.

In the above description, the transmitting and receiving optical module is described as a pair of a light emitting element as a transmitting optical element and a light receiving element as a receiving optical element. The present invention can also be applied to an optical module for parallel transmission or an optical module for parallel reception. In this case, only a plurality of light emitting elements or only a plurality of light receiving elements are provided inside the IC package. Even if the same light emitting element or light receiving element is used, there is still a possibility of stray light interference. Therefore, the present invention is also effective for preventing stray light interference.

Each of the optical modules 21, 31,
When an optical fiber cord having a transmission optical fiber is connected to 41, the ferrules 2 and 2 'of the optical modules 21, 31, and 41 and the tip of the optical fiber cord are attached in the same manner as described with reference to FIG. Said ferrule 2,
2 ′ is connected to the MT optical connector having the same structure.

[0017]

According to the present invention, there is provided an optical module in which a ferrule containing an optical fiber is integrally connected to a case provided with a plurality of optical elements. As a result, the following effects were obtained. Stray light from the light emitting element enters the adjacent light receiving element,
Alternatively, it is possible to prevent stray light from the optical fiber on the light receiving element from hitting the light emitting element, and it is possible to reliably prevent the occurrence of an abnormality in signal transmission and reception in the optical module. Since unnecessary light does not enter any of the optical elements, it is possible to prevent a problem that the optical elements are deteriorated due to the input of unnecessary light. When a metal or a partition member containing a metal is used, an electromagnetic wave is shielded, so that the light output as the electromagnetic wave out of the light output of the light emitting element may adversely affect the sensitivity of the light receiving element. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of an optical module according to one embodiment of the present invention with a lid removed.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view showing a state where a cover of an optical module according to another embodiment of the present invention is removed.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a sectional view taken along the line CC of FIG. 3;

FIG. 6 is a sectional view taken along line DD of FIG. 3;

FIG. 7 is a plan view of an optical module according to still another embodiment of the present invention with a lid removed.

FIG. 8 is a left side view of FIG. 7;

FIG. 9 is a plan view showing an example of a conventional optical module with a lid removed.

FIG. 10 is a sectional view taken along line EE of FIG. 9;

FIG. 11 shows another example of a conventional optical module.
It is a top view in the state where a lid was removed.

FIG. 12 is a left side view of the ferrule in FIG. 9;

13 is a sectional view taken along line FF of FIG.

FIG. 14 is a plan view showing a state where a cover is removed when an optical fiber cord with an MT optical connector is connected to the optical module of FIG. 9;

FIG. 15 is a diagram for explaining a problem of a conventional optical module. FIG. 15A shows a case where light emitted from an LD is a problem.
(B) shows a case where light incident on the PD becomes a problem, and (c) shows a case where an electromagnetic wave becomes a problem between adjacent optical elements.

[Explanation of symbols]

 2, 2 'ferrule 2a bonding end face 2b rear end face 3, 3' IC package (case) 5 light emitting element (optical element) 6 light receiving element (optical element) 7 optical fiber 11, 12, 33, 34, 44 mount 21, 31 , 41 Optical module 24 Substrate 30 Partition member 32a, 32b, 43 Space 42 Optical element

Claims (2)

[Claims] 1. A ferrule having a plurality of optical fibers built therein and having a front end serving as a joint end face for butt connection and exposing an end face of the optical fiber to a rear end face, and a plurality of optical elements corresponding to the plurality of optical fibers. In an optical module comprising a case arranged side by side and an optical fiber end face integrally connected to each optical element, the inside of the case is partitioned into a plurality of spaces for accommodating the optical elements. An optical module, characterized in that: 2. The optical module according to claim 1, wherein a metal or a material containing a metal is used as a partition member for partitioning a space in which each of the optical elements is housed.