JP2002368321A - Light emitting module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting module the semiconductor light emitting element of which can be controlled more precisely by sufficiently securing the quantity of light received by means of a light receiving element for monitoring and more accurately grasping the light emitting state of the light emitting element. SOLUTION: This light emitting module 10 is provided with the semiconductor light emitting element 14, an optical fiber 22, and a half mirror 20. The module 10 is also provided with the light receiving element 18 for monitoring and a housing 12. The light emitting element 14 has a light emitting surface 14a and a light reflecting surface 14b. The optical fiber 22 has one end 22a which is optically coupled with the light emitting surface 14a of the element 14. The half mirror 20 transmits one part of the light emitted from the light emitting surface 14a of the element 14 and, at the same time, reflects the other part of the light. The light receiving element 18 for monitoring receives the light reflected by the mirror 20. The housing 12 houses at least the light emitting element 14 and light receiving element 18. The light emitting element 14, half mirror 20, and optical fiber 22 are arranged in this order along a prescribed axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a light emitting module.

[0002]

2. Description of the Related Art A light emitting module generally includes a semiconductor light emitting element such as a semiconductor laser and a light receiving element for monitoring such as a photodiode. Such a semiconductor light emitting element and a light receiving element are housed in a package. The light receiving element receives light from the semiconductor light emitting element and monitors a light emitting state. The package has a plurality of lead terminals, and the semiconductor light emitting element receives a drive signal via these lead terminals.

[0003]

However, in the above-mentioned conventional light emitting module, the light receiving element for monitoring is arranged on the back of the semiconductor light emitting element, and the light emitting state of the semiconductor light emitting element is received by receiving a small amount of back light. Was monitoring. Therefore, a sufficient monitor current cannot be obtained, and it becomes difficult to accurately grasp the light emitting state of the semiconductor light emitting device, and there is a possibility that the semiconductor light emitting device cannot be controlled accurately.

Further, the inventor is studying a light emitting module capable of achieving a transmission speed of 10 Gbps or more. In order to achieve a transmission speed of about 10 Gbps, the inventor has found that not only the operation speed of the driving element itself is important, but also that the driving element is disposed close to the semiconductor light emitting element. Was found. Based on this finding, the inventor has considered arranging the driving element close to the back surface of the semiconductor light emitting element. However, if the driving element is arranged close to the back surface of the semiconductor light emitting element, the semiconductor light emitting element and the light receiving element for monitoring need to be arranged apart by that much, and as a result, the light received by the light receiving element becomes If the amount of light is further reduced, the above-described problem may become more serious.

SUMMARY OF THE INVENTION Accordingly, the present invention is to secure a sufficient amount of light received by a monitor light receiving element, more accurately grasp the light emitting state of the semiconductor light emitting element, and control the semiconductor light emitting element more accurately. It is an object of the present invention to provide a light emitting module capable of performing the following.

[0006]

A light emitting module according to the present invention comprises a semiconductor light emitting device, an optical fiber, a half mirror,
A monitor light receiving element and a housing are provided. The semiconductor light emitting device has a light emitting surface and a light reflecting surface. The optical fiber has one end optically coupled to the light emitting surface of the semiconductor light emitting device. The half mirror transmits a part of the light emitted from the light emitting surface of the semiconductor light emitting element and reflects another part. The monitoring light receiving element receives the light reflected by the half mirror. The housing houses at least a semiconductor light emitting element and a monitor light receiving element. The semiconductor light emitting element, the half mirror, and the optical fiber are arranged in this order along a predetermined axis.

In this light emitting module, a part of the light emitted from the light emitting surface of the semiconductor light emitting element passes through the half mirror and enters the optical fiber. Another part of the light emitted from the light emitting surface of the semiconductor light emitting element is reflected by the half mirror and received by the monitor light receiving element. As described above, the light received by the monitor light receiving element is the front light emitted from the light emitting surface of the semiconductor light emitting element, and the light intensity is sufficiently larger than the rear light emitted from the light reflecting surface. It is possible to ensure a sufficient amount of light received by the light receiving element, more accurately grasp the light emitting state of the semiconductor light emitting element, and more accurately control the semiconductor light emitting element. In addition, since the semiconductor light emitting element, the half mirror, and the optical fiber are arranged in this order along the predetermined axis, the positioning of each member becomes easy.

In the light emitting module according to the present invention, the housing may have a side wall extending along a predetermined axis, and the light receiving element for monitoring may be arranged on a ceramic terminal board provided on the side wall.

In the light emitting module according to the present invention, a light reflecting means for reflecting the light reflected by the half mirror may be provided on the inner wall surface of the housing. With this configuration, the reflected light from the half mirror can be reflected by the light reflecting means on the inner wall surface of the housing, and the reflected light can be received by the monitoring light receiving element. The degree of freedom is improved.

[0010] The light emitting module according to the present invention may further include a drive element for driving the semiconductor light emitting element disposed so as to sandwich the semiconductor light emitting element between the half mirror and the housing inside the housing. If you do this,
By arranging the driving element adjacent to the semiconductor light emitting element,
Transmission speed can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a light emitting module according to the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a partially cutaway perspective view showing a light emitting module according to this embodiment. The light emitting module 10
A housing 12, a semiconductor light emitting element 14, a semiconductor driving element 16, a monitor light receiving element 18, and a half mirror 2;
0 and an optical fiber 22.

The housing 12 has a pair of side walls 12a extending along a predetermined axis (X in FIG. 2), and a front wall 12b and a rear wall 12c intersecting the predetermined axis X. Each of the side wall portions 12a is provided with a plurality of lead terminals 12d,
The rear wall portion 12c is provided with a plurality of lead terminals 12e. A ceramic terminal board 24 extending along a predetermined axis X is provided on each of the side wall portions 12a.
The ceramic terminal board 24 is provided so as to protrude inside, and is electrically connected to the lead terminals 12d.

Semiconductor light emitting element 14, semiconductor driving element 1
6 and the monitor light-receiving element 18
2 housed. The semiconductor light emitting device 14 generates light modulated based on a modulation signal. As the semiconductor light emitting element 14, for example, a semiconductor laser element can be used. Semiconductor drive element 16 receives the modulation signal received via lead terminal 12e. The modulation signal is a signal for modulating the semiconductor light emitting element 14. The semiconductor drive element 16 amplifies the modulation signal to generate a drive signal. The drive signal is provided to the semiconductor light emitting device 14.

On the bottom surface 12f of the housing 12, a first
Is provided. First mounting member 26
Is made of a conductive material such as a metal. The first mounting member 26 is supported by a support member 28. The first mounting member 26 has a mounting surface 26a and a lens support 26b. The lens support portion 26b is
Are supported. The first lens support member 30 holds the first lens (32 in FIG. 2).

On the mounting surface 26a of the first mounting member 26, the semiconductor light emitting element 14, the semiconductor driving element 16, and the wiring board 34 are mounted. The semiconductor light emitting element 14 is mounted on a second mounting member 36 such as a submount, and the second mounting member 36 is disposed on the mounting surface 26a. The second mounting member 36 is made of, for example, a material having excellent thermal conductivity.

The semiconductor driving element 16 is the semiconductor light emitting element 1
4 is directly mounted on the mounting surface 26a so as to be adjacent to the semiconductor light emitting element 14 on the side of the light reflecting surface (14b in FIG. 2). According to experiments by the inventor, it has been found that in order to achieve high-speed transmission such as 10 Gbps, the distance between the semiconductor driving element 16 and the semiconductor light emitting element 14 needs to be 1 mm or less.

One electrode of the semiconductor light emitting element 14 is electrically connected to a power supply potential line via a bonding wire (38 in FIG. 2). The other electrode of the semiconductor light emitting element 14 is electrically connected to the semiconductor drive element 16 via a bonding wire (40 in FIG. 2).

The wiring board 34 is mounted directly on the mounting surface 26a. The wiring board 34 is made of an insulating material such as AlN. This wiring board 34 has a wiring surface. A pair of transmission paths 34a and 34b extending from one side of the pair of sides to the other side are provided on the wiring surface. A conductive layer (3 in FIG. 2) is provided between these transmission lines 34a and 34b.
4c, 34d, 34e) are provided. Conductive layer 34
c, 34d, and 34e are connected to the ground potential line.
One end of each of the transmission lines 34a and 34b is electrically connected to the semiconductor drive element 16 via a bonding wire 42. The other ends of the transmission paths 34a and 34b are connected to the lead terminals 12e of the housing 12 and bonding wires (not shown).
Are electrically connected via

The front wall 12b of the housing 12 faces the lens support 26b of the first mounting member 26. The front wall 12b is provided with a hole 12g through which light from the semiconductor light emitting element 14 passes. The holding member 4 is provided in the hole 12g.
4 is disposed, and the holding member 44 is the half mirror 20.
Holding. On the outer surface of the front wall portion 12b of the housing 12, the second lens holding member 4
6 are arranged at one end. Second lens holding member 46
Holds a lens 48 such as a condenser lens. A ferrule holder 50 is disposed at the other end of the second lens holding member 46. The ferrule holder 50 has a hole for accommodating the ferrule 52. Ferrule 52
The optical fiber 22 is inserted so that one end of the optical fiber 22 is protected. Optical fiber 22 is aligned with lens 48 via ferrule 52 and ferrule holder 50. Thereby, light from the semiconductor light emitting element 14 is input to one end of the optical fiber 22. The protection member 54 covers the second lens holding member 46, the ferrule holder 50, and the ferrule 52.
As the protection member 54, a rubber cap can be used. The optical fiber 22 is taken out of the housing 12 through the protection member 54. The other end of the optical fiber 22 is provided with an optical coupling device 56 such as an optical connector. The optical coupling device 56 provides light from the semiconductor light emitting element 14 that has propagated through the optical fiber 22. In the present embodiment, the optical coupling device 56 is
A ferrule provided at the other end of the optical fiber 22 can be included.

The monitor light receiving element 18 is disposed on the ceramic terminal board 24. More specifically, the monitoring light-receiving element 18 is arranged at a position close to the half mirror 20 on one of the ceramic terminal boards 24 so as to receive the light reflected by the half mirror 20. The light receiving surface of the monitor light receiving element 18 is a half mirror 2
0, it is optically coupled to the light emitting surface 14a of the semiconductor light emitting element 14. The monitoring light receiving element 18 monitors the light emitting state of the semiconductor light emitting element 14. As the monitoring light receiving element 18, an element capable of converting light into a current, for example, a photodiode can be used.

FIG. 2 is a plan view showing the electrical and optical coupling of the electronic and optical elements included in the light emitting module 10, and FIG. FIG. 4 is a side view showing a target and an optical connection.

Referring to FIG. 2 and FIG.
2, lens 48, half mirror 20, lens 32, semiconductor light emitting element 14, semiconductor drive element 16, and wiring board 3
4 are arranged in this order along the predetermined axis X. The semiconductor light emitting element 14 includes a light emitting surface 14a and a light reflecting surface 14a.
b. The light emitting surface 14a and the light reflecting surface 14b are
An optical resonator of the light emitting module 10 is configured. The light emitting surface 14a of the semiconductor light emitting element 14 is optically coupled to one end 22a of the optical fiber 22 by a lens 32 and a lens 48. Light reflecting surface 14b of semiconductor light emitting element 14
Has a reflectance set to approximately 100%, and the conversion efficiency of the injected current into light is increased.

The light A emitted from the light emitting surface 14a of the semiconductor light emitting element 14 passes through a hole 26c provided in a lens support 26b, and a lens 32 such as a collimator lens.
To reach. The lens 32 changes the traveling direction of the light A and directs the light A in a direction along a predetermined axis X. The light B whose traveling direction has been changed by the lens 32 reaches the half mirror 20. Part of the light B that has reached the half mirror 20 passes through the half mirror 20 and passes through the lens 4 such as a condenser lens.
Reach 8. The lens 48 changes the traveling direction of the light C transmitted through the half mirror 20 and
The light D is directed to 2a. The light D is introduced into an optical fiber 22 having a core 22b and a clad 22c covering the core 22b. Then, the light E propagating through the core portion 22b reaches the other end 22d of the optical fiber 22, and passes through the optical coupling device 56 to another optical coupling device (not shown).
Will be introduced.

On the other hand, another part of the light B that has reached the half mirror 20 is reflected by the half mirror 20. The half mirror 20 is arranged to be inclined at a desired angle with respect to the predetermined axis X. Therefore, half mirror 2
The light F reflected by the light reaches the monitor light receiving element 18 arranged on the ceramic terminal board 24 and is received. Then, the semiconductor driving element 16 performs the semiconductor light emitting element 1 based on the light received by the monitoring light receiving element 18.
The light emitting state of No. 4 is analyzed, and the light emitting power of the semiconductor light emitting element 14 is automatically controlled.

As described above, the light emitting module 1 according to the present embodiment
At 0, the light received by the monitoring light receiving element 18 is
This is front light emitted from the light emitting surface 14a of the semiconductor light emitting element 14 and has a sufficiently large amount of light than the back light emitted from the light reflecting surface 14b. Semiconductor light emitting device 1
The light emitting state of the semiconductor light emitting element 1 is more accurately grasped.
4 can be controlled more accurately. Therefore, in the light emitting module 10 according to the present embodiment, stable emission characteristics can be obtained. In particular, the semiconductor light emitting device 14,
Since the half mirror 20 and the optical fiber 22 are arranged in this order along the predetermined axis X, the alignment of each member is easy, and the optical coupling between the semiconductor light emitting element 14 and the optical fiber 22 is ensured. Things.

The light emitting module 10 according to the present embodiment
Since the semiconductor driving element 16 is disposed adjacent to the semiconductor light emitting element 14, the transmission speed can be improved. In the conventional light emitting module, the monitoring light receiving element is disposed on the back of the semiconductor light emitting element, and monitors the light emitting state of the semiconductor light emitting element by receiving a small amount of back light. Therefore, if the driving element is arranged close to the back surface of the semiconductor light emitting element, the semiconductor light emitting element and the light receiving element for monitoring need to be arranged correspondingly, and a sufficient monitor current cannot be obtained. It becomes difficult to accurately grasp the light emitting state of the element, and there is a possibility that the semiconductor light emitting element cannot be controlled accurately.
In contrast, the light emitting module 10 according to the present embodiment
Since the front light emitted from the light emitting surface 14a of the semiconductor light emitting element 14 is monitored, the semiconductor driving element 16 is adjacent to the light reflecting surface 14b of the semiconductor light emitting element 14 in order to improve the transmission speed. Even if the semiconductor light-emitting element 14 is disposed, the light amount of the light received by the monitor light-receiving element 18 is sufficiently ensured, the light-emitting state of the semiconductor light-emitting element 14 is grasped more accurately, and the semiconductor light-emitting element 14 is more accurately controlled. be able to.

Here, JP-A-7-122760 discloses an LD module for monitoring front light emitted from a light emitting surface of a laser diode (LD) and controlling the LD. In this LD module, a light reflecting means is provided in a light receiving section of the PD chip. And LD
The light emitted from the light emitting surface of the chip and transmitted through the light reflecting means provided in the light receiving portion of the PD chip is received and monitored, and the light reflected by the light reflecting means is introduced into the optical fiber. However, since the LD module has a configuration in which the reflected light from the PD chip is introduced into the optical fiber, alignment of the LD, the PD chip, and the optical fiber is difficult, and the optical coupling between the LD and the optical fiber is ensured. It may not be done. On the other hand, in the light emitting module 10 according to the present embodiment, the semiconductor light emitting element 14 and the optical fiber 22 are arranged along the predetermined axis X, and the half mirror 20 is arranged between them. This is excellent in that alignment is easy and optical coupling between the semiconductor light emitting element 14 and the optical fiber 22 is ensured.

It should be noted that the present invention can be variously modified irrespective of the embodiment described above.

For example, in the light emitting module 10 according to the above-described embodiment, the light reflected by the half mirror 20 is directly received by the monitoring light receiving element 18. However, the present invention is not limited to this. As shown in FIG. 4, light reflecting means 60 for reflecting the light reflected by the half mirror 20 is provided on the inner wall surface of the housing 12, and the light reflected by the light reflecting means 60 is provided. May be received by the monitor light-receiving element 18. At this time, the monitoring light-receiving element 18 is arranged, for example, on the wiring board 34. This makes it possible to dispose the monitor light-receiving element 18 even in a place where the reflected light from the half mirror 20 cannot be directly received, and the degree of freedom of the position for disposing the monitor light-receiving element 18 can be increased. Is improved.
As the light reflection means 60, for example, a total reflection mirror can be used. When the surface of the housing 12 that can reflect light is made of a material such as gold-plated metal, the inner wall surface of the housing 12 can also serve as the light reflecting means 60.

In the above-described embodiment, the holding member 4 disposed in the hole 12g of the front wall portion 12b of the housing 12 is provided.
4, the half mirror 20 is held, but the hermetic glass is arranged at the position where the half mirror 20 is held, and any position between the hermetic glass and the lens 32 on the predetermined axis X. The half mirror 20 may be arranged at the bottom.

In the light emitting module 10 according to the above-described embodiment, the first mounting member 26 is
Instead of 8, it may be supported on a thermoelectric cooler such as a Peltier element. The thermoelectric cooler is electrically connected to the lead terminal 12 d and controls the temperature of the electronic elements mounted on the first mounting member 26, for example, the semiconductor light emitting element 14 and the semiconductor drive element 16. It may be. By doing so, it is possible to further stabilize the emission characteristics of the light emitting module 10.

It is clear from the above description of the present invention that the present invention can be variously modified. Such modifications cannot be deemed to depart from the spirit and scope of the invention, and modifications obvious to all those skilled in the art are:
It is within the scope of the present invention.

[0034]

As described in detail above, in the light emitting module according to the present invention, the light quantity of the light received by the light receiving element for monitoring is sufficiently ensured, and the light emitting state of the semiconductor light emitting element can be grasped more accurately. As a result, the semiconductor light emitting device can be controlled more accurately. Therefore, according to the light emitting module of the present invention, stable emission characteristics can be obtained. According to the light emitting module of the present invention,
Since the semiconductor light emitting element, the half mirror, and the optical fiber are arranged in this order along the predetermined axis, the positioning of each member is easy, and the optical coupling between the semiconductor light emitting element and the optical fiber is more reliably performed. Things.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a light emitting module according to an embodiment.

FIG. 2 is a plan view illustrating electrical and optical coupling of an electronic element and an optical element included in the light emitting module according to the embodiment.

FIG. 3 is a side view showing electrical and optical coupling of an electronic element and an optical element included in the light emitting module according to the embodiment.

FIG. 4 is a plan view showing a modification of the light emitting module according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Light emitting module, 12 ... Housing, 12a ... Side wall part, 14 ... Semiconductor light emitting element, 14a ... Light emission surface, 14
b: light reflecting surface, 16: semiconductor drive element, 18: monitor light receiving element, 20: half mirror, 22: optical fiber, 2
4 ceramic terminal board, 60 light reflecting means, X predetermined axis.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04B 10/135 10/14 F-term (Reference) 2H037 AA01 BA03 DA03 DA04 DA05 DA06 DA15 5F073 AB27 AB28 AB29 BA02 FA25 FA30 5F089 AA01 BC11 CA15 CA20 GA03 GA10 5K002 BA01 BA21 BA31

Claims (4)

[Claims] A semiconductor light emitting device having a light emitting surface and a light reflecting surface; an optical fiber having one end optically coupled to the light emitting surface of the semiconductor light emitting device; A half mirror that transmits a part of the light emitted from the surface and reflects another part, a monitoring light receiving element that receives the light reflected by the half mirror, and at least the semiconductor light emitting element and the monitor A light-emitting module comprising: a housing for housing a light-receiving element; wherein the semiconductor light-emitting element, the half mirror, and the optical fiber are arranged in this order along a predetermined axis. 2. The light emitting device according to claim 1, wherein the housing has a side wall extending along the predetermined axis, and the monitor light receiving element is disposed on a ceramic terminal board provided on the side wall. module. 3. The light emitting module according to claim 1, wherein light reflecting means for reflecting light reflected by the half mirror is provided on an inner wall surface of the housing. 4. The light emitting module according to claim 1, further comprising: a driving element for driving the semiconductor light emitting element disposed so as to sandwich the semiconductor light emitting element between the half mirror and the housing. .