JPH08201666A - Transmission/reception optical module - Google Patents

Abstract

PURPOSE: To provide a transmission/reception optical module capable of highly maintaining coupling efficiency between an optical transmission line and a condenser lens, optical parts, a light emitting element and a light receiving element, etc., for the change in a temp. and the humidity of the use environment or the secular change, etc., without using a high-degree fusion splicing technique. CONSTITUTION: The whole of a base 1, the light emitting element 5, the light receiving elements PD1, PD2, the condenser lens 9 and the optical parts 3 is integrated, and is constituted so as to be movable to an optical transmission line 10 fixed to an optical transmission line 11, and the whole of these base 1, the light emitting element 5, the light receiving elements PD1, PD2, the condenser lens 9 and the optical parts 3 is integrated, and is moved to the optical transmission line 10 according to a receiving signal beam, for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting / receiving optical module, and is particularly suitable for bidirectional optical communication.

[0002]

2. Description of the Related Art In recent years, expectations for multimedia, such as the so-called information super highway concept, have been increasing, and research and development have been actively conducted with the aim of realizing it. It is considered that due to the development of this multimedia, an era in which one or more optical fibers are connected to one household and bidirectional optical communication can be performed through the optical fibers will arrive in the near future. By the way, at this time, a transmission / reception optical module that can perform transmission / reception with a single optical fiber is essential in terms of cost.

Conventionally, as this type of transmitting / receiving optical module, one using a hologram is known (for example,
JP-A-5-203845 and JP-A-6-138
No. 322). FIG. 4 shows a schematic configuration of this conventional transmitting / receiving optical module. As shown in FIG. 4, in this conventional transmitting / receiving optical module, a light emitting element 102 and a light receiving element 103 are provided on a support base 101. The light emitting element 102 and the light receiving element 103 are package 1
It is sealed by 04. A hologram 105 is attached to a portion of the package 104 above the light emitting element 102 using a resin adhesive. Code 10
Reference numeral 6 denotes a condenser lens attached to a fixed position with respect to the package 104. An optical fiber 107 is connected to the transmission / reception optical module so that one end surface of the condenser lens 106 faces. In this transmission / reception optical module, at the time of transmission, the transmission signal light emitted from the light emitting element 102 is incident on one end surface of the optical fiber 107 via the hologram 105 and the condenser lens 106, and the transmission signal light is transmitted through this optical fiber 107. It is sent to the receiving side. On the other hand, when receiving, the optical fiber 10
Received signal light emitted from one end surface of the condenser lens 10
After being condensed by 6, it is diffracted by the hologram 105 and enters the light receiving element 103.

[0004]

By the way, in the above-mentioned conventional transmitting / receiving optical module, the optical fiber 107, the condenser lens 106, the hologram 105, and the light emitting element are responded to changes in the temperature and humidity of the operating environment or changes with time. It is indispensable to keep the coupling efficiency between the light receiving element 102 and the light receiving element 103 and the like high at all times.
Optical fiber 107, condenser lens 106, hologram 1
05, the light emitting element 102, the light receiving element 103 and the like are secured only by fixing with an adhesive or the like.

However, considering that the transmission / reception optical module is generally used in various situations, a very high technique is required for the above-mentioned fixing, and this is because of the manufacturing cost and mass productivity. It is a big obstacle to practical use.

Therefore, an object of the present invention is to use an optical transmission line and a condensing lens, an optical component, a light emitting element, against a change in temperature or humidity of a use environment or a change over time without using an advanced fixing technique. An object of the present invention is to provide a transmission / reception optical module that can always maintain high coupling efficiency with a light receiving element or the like.

[0007]

In order to achieve the above object, a transmitting / receiving optical module according to the present invention comprises a substrate (1).
A light emitting element (5) and a light receiving element (PD1, PD2) provided on the substrate (1), a condenser lens (9) for condensing the transmission signal light or the reception signal light, and the light emitting element ( 5) The transmission signal light emitted from the optical transmission line (10) is made incident on one end face of the optical transmission line (10) for transmission and reception, and the reception signal light emitted from one end face of the optical transmission line (10) is received by the light receiving elements (PD1, PD2). ) Optical component (3)
And at least the condenser lens (9) is configured to be movable with respect to the optical transmission line (10) fixed to the optical transmission line fixing portion (11).

In one embodiment of the present invention, a substrate,
The light emitting element, the light receiving element, the condenser lens, and the optical component as a whole are moved together with respect to the optical transmission line according to the received signal light. More specifically, when the received signal light is received by the light receiving element, the output signal obtained from this light receiving element is used to perform optical transmission of the substrate, the light emitting element, the light receiving element, the condenser lens, and the optical component as a whole. Move it to the track.

In another embodiment of the present invention, the substrate, the light emitting element, the light receiving element and the optical component are fixed to the optical transmission line, and the condenser lens is fixed to the optical transmission line according to the received signal light. To move. More specifically, when the received signal light is received by the light receiving element, the output lens obtained from the light receiving element is used to move the condenser lens with respect to the optical transmission line.

In an exemplary embodiment of the invention,
The base is a base having a high-frequency transmission line. Specifically, the base having the high-frequency transmission line is, for example, a ceramic substrate having a microstrip line.

In the present invention, typically, the light emitting element, the light receiving element and the optical component are sealed by a package, and the condenser lens is attached to this package.

In one embodiment of the present invention, another substrate is provided on the substrate, and the light emitting element and the light receiving element are provided on the other substrate. Here, typically, the other base is a semiconductor substrate, and the light receiving element is a photodiode provided on the semiconductor substrate. As this photodiode, for example, an 8-division type is used. This semiconductor substrate is usually provided with an electronic circuit such as an amplifier circuit in addition to the photodiode.

In the present invention, the light emitting element is typically a semiconductor laser. Moreover, the optical component is, for example, a prism or a hologram. Further, the optical transmission line is typically an optical fiber.

[0014]

According to the transmission / reception optical module of the present invention constructed as described above, at least the condenser lens is constructed so as to be movable with respect to the optical transmission line. By moving the lens and aligning it correctly with the optical transmission line, the coupling efficiency between the optical transmission line and at least the condenser lens is always high against changes in the operating environment such as temperature and humidity or changes over time. Can be maintained. In this case, in particular, by moving the substrate, the light emitting element, the light receiving element, the condenser lens, and the optical component as a whole with respect to the optical transmission line according to the received signal light, a change in temperature or humidity of the use environment or The coupling efficiency between the optical transmission line and the condenser lens, the optical component, the light emitting element, the light receiving element and the like can be constantly maintained high against changes with time. Then, at this time, it is not necessary to fix the optical transmission line and the condenser lens, the optical component, the light emitting element, the light receiving element and the like by using an advanced fixing technique.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a transmitting / receiving optical module according to a first embodiment of the present invention.

As shown in FIG. 1, in the transmitting / receiving optical module according to the first embodiment, for example, a photo is formed on a ceramic substrate 1 on which microstrip lines (not shown) for high speed digital communication are formed as input / output lines. The diode IC2 is mounted. The photodiode IC2 has a pair of photodiodes PD1 and PD2 for detecting an optical signal, a driving circuit of a semiconductor laser 5 and a receiving / amplifying circuit (not shown) which will be described later, which are integrated on a Si substrate, for example. Is. Here, the photodiodes PD1 and PD2 are 8-division type having a pattern as shown in FIG. Although not shown, a half mirror having a reflectance of, for example, about 50% made of, for example, a dielectric multilayer film is provided on the surface of the photodiode PD1.

A micro prism 3 made of, for example, optical glass is mounted on the photodiode IC2 so as to cover the photodiodes PD1 and PD2, and a LOP (Laser on Photodiode) having a semiconductor laser 5 mounted on the photodiode 4 is mounted. ) The chip is mounted adjacent to this micro prism 3. In this case, the micro prism 3 is adhered to the photodiode IC 2 with, for example, an epoxy resin adhesive or a silicone resin adhesive. On the other hand, the LOP chip is mounted by die-bonding the photodiode 4 on a predetermined die pad (not shown) provided on the photodiode IC2. The photodiode 4 is composed of, for example, a Si chip, and the semiconductor laser 5 is, for example, a GaAs / AlGaAs semiconductor laser. The photodiode 4 is for monitoring the light output from the end face on the rear side of the semiconductor laser 5, and thereby monitoring the light output from the end face on the front side.

The micro prism 3 has a reflecting surface 3b which is inclined at a predetermined angle with respect to the bottom surface 3a, for example, 45 °. Although not shown, a half mirror having a reflectance of, for example, about 50% made of, for example, a dielectric multilayer film is provided on the reflecting surface 3b. A total reflection film 6 made of, for example, a dielectric multilayer film is provided on the upper surface 3c of the micro prism 3. Further, a light absorbing film 7 is provided on an end surface 3d of the micro prism 3 on the side opposite to the semiconductor laser 5, and the light absorbing film 7 can absorb stray light which becomes noise light. .

Reference numeral 8 indicates a package. The package 8 seals the photodiode IC 2, the micro prism 3, and the LOP chip. As the package 8, for example, a resin mold package, a ceramic package, a metal package, or the like can be used.

Further, a condenser lens 9 for condensing the transmission signal light or the reception signal light is attached to a portion of the package 8 above the reflecting surface 3b of the micro prism 3.

Reference numeral 10 indicates an optical fiber. The optical fiber 10 is fixed to the optical fiber fixing portion 11. Here, the optical fiber 10 is fixed to the optical fiber fixing portion 11 so that one end surface thereof faces the condenser lens 9.

In the first embodiment, a transmission / reception optical module comprising a photodiode IC2, a microprism 3 and a LOP chip sealed on a ceramic substrate 1 by a package 8 and a condenser lens 9 mounted on the package 8. Is movable in the X-axis direction, the Y-axis direction, and the Z-axis direction with respect to the optical fiber fixing portion 11. Here, the movement of the transmission / reception optical module with respect to the optical fiber fixing portion 11, and thus the optical fiber 10, is performed by controlling the servo system 12 according to the received signal light. As the moving mechanism of the transmission / reception optical module, for example, the same mechanism as the moving mechanism (biaxial actuator) of the objective lens of the optical pickup of the optical disc player can be used.

Next, a method of transmitting and receiving by the transmitting and receiving optical module according to the first embodiment configured as described above will be described.

First, at the time of transmission, the semiconductor laser 5 is driven according to the signal to be transmitted, so that signal light is emitted from the semiconductor laser 5. This signal light is reflected by the half mirror on the reflecting surface 3b of the microprism 3, is further condensed by the condenser lens 9, enters the one end surface of the optical fiber 10, and passes through the optical fiber 10 to the receiving side. Sent. In addition, of the signal light emitted from the semiconductor laser 5, the reflecting surface 3 of the microprism 3
This micro prism 3 is transmitted through the half mirror on the b.
The light that has traveled to the inside of the light strikes the light absorption film 7 and is absorbed.

On the other hand, at the time of reception, the signal light transmitted from the transmission side through the optical fiber 10 is transmitted to the optical fiber 1.
It is emitted from one end surface of 0. This signal light is collected by the condenser lens 9
After being collected by the reflective surface 3b of the micro prism 3,
The light passes through the upper half mirror and enters the inside of the micro prism 3. Half of the signal light that has entered the inside of the micro prism 3 passes through a half mirror provided on the surface of the photodiode PD1 and enters the photodiode PD1, and is converted into an electric signal by the photodiode PD1. It On the other hand, this micro prism 3
The other half of the signal light entering the inside of the photodiode PD is sequentially reflected by the half mirror and the total reflection film 6 provided on the surface of the photodiode PD1 and
It is incident on 2 and is converted into an electric signal by the photodiode PD2. Since the light reflected on the surface of the photodiode PD2 finally strikes the light absorption film 7 and is absorbed, there is almost no return light to the optical fiber 10.

In the first embodiment, the alignment of the transmission / reception optical module with respect to the optical fiber 10 is performed as follows by using the received signal light.

That is, the received signal light emitted from one end surface of the optical fiber 10 passes through the condenser lens 9, further passes through the half mirror on the reflecting surface 3b of the micro prism 3, and enters the inside of this micro prism 3. The spot size on the photodiodes PD1 and PD2 at this time is as follows when the transmission / reception optical module is aligned with the optical fiber 10 in the Z-axis direction, that is, when the focus position of the condenser lens 9 is on one end face of the optical fiber 10. They are the same as each other. On the other hand, if the focal position of the condenser lens 9 shifts from the one end surface of the optical fiber 10 in the Z-axis direction, the spot sizes on the photodiodes PD1 and PD2 become different from each other. Therefore, if the output signals from these photodiodes PD1 and PD2 are made to correspond to the displacement of the transmitting / receiving optical module in the Z-axis direction, the focus error signal can be detected. Specifically, the output signals from the respective parts of the pattern of the 8-division photodiodes PD1 and PD2 shown in FIG.
When ₁ to A ₈ and _{B 1 ~B 8, (A 1} + A 4 + A
₅ + A ₈ + B ₂ + B ₃ + B ₆ + B ₇ )-(A ₂ + A ₃ +
A ₆ + A ₇ + B ₁ + B ₄ + B ₅ + B ₈ ) forms a focus error signal. At this time, the zero point of this focus error signal is a point at which the transmission / reception optical module is correctly aligned in the Z-axis direction with respect to the optical fiber 10.
That is, it corresponds to the just focus point. Therefore, the servo system 1 is set so that this focus error signal becomes zero.
2 is fed back, and the transmitting / receiving optical module is aligned with the optical fiber 10 in the Z-axis direction.

Next, the optical fiber 1 in the XY plane
In order to align the transmission / reception optical module with respect to 0, output signals A _{1 to} A ₈ and B _{1 to} B ₈ from the respective parts of the pattern of the photodiodes PD1 and PD2 are used, and (A ₁ + A ₂ ) − (A ₇ + A ₈ ) and (B ₁ + B
_{2) - (B 7 + B} 8) by forming an alignment error signals in the X-axis direction and the Y-axis direction. At this time, the zero point of this alignment error signal corresponds to the point at which the transmission / reception optical module is correctly aligned with the optical fiber 10 in the X-axis direction and the Y-axis direction. Therefore, the servo system 12 is controlled so that this alignment error signal becomes zero.
Is fed back to align the transmission / reception optical module with respect to the optical fiber 10 in the X-axis direction and the Y-axis direction. _{Incidentally, (A 5 + A 6)} - it may form a X-axis direction and the Y-axis direction of the alignment error signal by _{(B 3 + B 4) -} (A 3 + A 4) and (B ₅ + B _6).

As described above, according to the first embodiment,
The transmission / reception optical module is configured to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction with respect to the optical fiber 10, and the transmission / reception optical module is moved in the X-axis direction, the Y-axis direction, and the Z-axis direction using the received signal light. By doing so, the transmitting / receiving optical module is correctly aligned with respect to the optical fiber 10 so as to come to the optimum coupling position. For this reason, the coupling efficiency between the optical fiber 10 and the transmission / reception optical module, that is, the condenser lens 9, the micro prism 3, etc., is always kept high against changes in temperature and humidity of the environment in which the transmission / reception optical module is used or changes with time. can do.

Further, in the transmitting / receiving optical module according to the first embodiment, the photodiode 4 and the semiconductor laser 5 as well as the micro prism 3 are provided on the photodiode IC2 provided with the photodiodes PD1 and PD2.
Since the LOP chip made of is integrally formed, it can be miniaturized and is excellent in mass productivity. Furthermore, since there is almost no stray light that becomes noise light, it has excellent noise resistance.

FIG. 3 shows a transmitting / receiving optical module according to a second embodiment of the present invention. As shown in FIG. 3, in the transmitting / receiving optical module according to the second embodiment, for example, two photodiodes are provided on a ceramic substrate 21 on which microstrip lines (not shown) for high-speed digital communication as input / output lines are formed. The ICs 22 and 23 are mounted at a predetermined distance from each other. Photodiode I
C22 is, for example, a photodiode PD11 for detecting an optical signal, a reception amplifier circuit (not shown), and the like integrated into an IC on, for example, a Si substrate. Similarly, the photodiode IC23 is a photodiode PD for detecting an optical signal.
In addition to 12, a reception amplifier circuit (not shown), etc.
It is an IC on an i substrate. These photodiodes PD11 and PD12 are 8-division type having the same pattern as shown in FIG.

A LOP chip having a semiconductor laser 25 mounted on a photodiode 24 is mounted on the ceramic substrate 21 in a portion between the photodiode ICs 22 and 23. In this case, this LOP chip
The semiconductor laser 25 is mounted so that the emitting direction of the laser light is perpendicular to the surface of the ceramic substrate 21.

Reference numeral 26 indicates a package. The package IC 26 seals the photodiode ICs 22 and 23 and the LOP chip.

A hologram 27 is attached to a portion of the package 26 above the LOP chip.
Further, a condenser lens 28 for condensing the transmission signal light or the reception signal light is attached to the package 26 above the hologram 27.

Reference numeral 29 indicates an optical fiber. The optical fiber 29 is fixed to the optical fiber fixing portion 30. Here, the optical fiber 29 has an optical fiber fixing portion 30 such that one end surface of the optical fiber 29 faces the condenser lens 28.
It is fixed to.

In the second embodiment, transmitted / received light composed of photodiode ICs 22 and 23 and a LOP chip sealed by a package 26 on a ceramic substrate 21 and a hologram 27 and a condenser lens 28 attached to the package 26. The module is movable in the X-axis direction, the Y-axis direction, and the Z-axis direction with respect to the optical fiber fixing section 30. Here, the movement of this transmission / reception optical module with respect to the optical fiber fixing section 30, and thus the optical fiber 29, is performed by controlling the servo system 31 according to the received signal light. Similar to the first embodiment, as the moving mechanism of the transmitting / receiving optical module, for example, the same moving mechanism as the moving mechanism of the optical pickup of the optical disc player can be used.

Next, a method of transmitting and receiving by the transmitting / receiving optical module according to the second embodiment configured as described above will be described.

First, at the time of transmission, the semiconductor laser 25 is driven according to the signal to be transmitted, so that signal light is emitted from the semiconductor laser 25. The signal light passes through the hologram 27, is condensed by the condenser lens 28, enters the one end surface of the optical fiber 29, and is transmitted to the receiving side through the optical fiber 29.

On the other hand, at the time of reception, the signal light transmitted from the transmission side through the optical fiber 29 is transmitted to the optical fiber 2.
It is emitted from one end surface of 9. This signal light is condensed by the condensing lens 28, then diffracted by the hologram 27, and the photodiode PD of the photodiode IC 22.
11 and the photodiode PD12 of the photodiode IC23, and these photodiode PD1
1 and PD 12 respectively convert into electric signals.

In this second embodiment, the optical fiber 2
Positioning of the transmission / reception optical module with respect to 9 is performed by moving the transmission / reception optical module in the X-axis direction, the Y-axis direction, and the Z-axis direction using the received signal light, as described in the first embodiment. That is, the focus error signal is formed from the output signals from the respective parts of the pattern of the 8-division photodiodes PD11 and PD12, and the servo system 31 is fed back so that the focus error signal becomes zero, so that the optical fiber 29 is fed. The transmission / reception optical module is aligned with the Z-axis direction. In addition, these photodiode PD1
1 and the alignment signals in the X-axis direction and the Y-axis direction are formed from the output signals from the respective parts of the pattern of the PD 12,
Servo system 31 so that this alignment signal becomes zero
Optical fiber 2 by giving feedback to
The transmission / reception optical module is aligned with the X-axis direction and the Y-axis direction with respect to 9.

As described above, according to this second embodiment,
The transmission / reception optical module is configured to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction with respect to the optical fiber 29, and this transmission / reception optical module is moved in the X-axis direction, the Y-axis direction, and the Z-axis direction using the received signal light. By doing so, the transmission / reception optical module is correctly aligned with the optical fiber 29 so as to come to the optimum coupling position. Therefore, as in the first embodiment, the temperature and humidity of the environment in which the transmission / reception optical module is used can be controlled. The coupling efficiency between the optical fiber 29 and the transmission / reception optical module, that is, the condenser lens 29, the hologram 27, and the like can be constantly maintained high against changes or changes over time.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the photodiode IC2 and the photodiode 4 in the first embodiment and the photodiode ICs 22 and 23 and the photodiode 24 in the second embodiment may be those using a GaAs substrate, for example.

In the first and second embodiments described above, the optical fibers 10 and 29 are fixed and the transmission / reception optical module is configured to be movable with respect to the optical fibers 10 and 29. Alternatively, the transmission / reception optical module may be fixed, and the optical fibers 10 and 29 may be movable with respect to the transmission / reception optical module.

[0046]

As described above, according to the transmitting / receiving optical module of the present invention, at least the condenser lens is configured to be movable with respect to the optical transmission line fixed to the optical transmission line fixing portion. It is possible to constantly maintain a high coupling efficiency between the optical transmission line and at least the condenser lens against changes in the temperature and humidity of the use environment or changes with time without using a high-level fixing technique. Furthermore, by moving the substrate, the light emitting element, the light receiving element, the condenser lens, and the optical component as a whole with respect to the optical transmission line, the optical transmission can be performed against changes in temperature and humidity of the operating environment or changes with time. The coupling efficiency between the line and the condenser lens, the optical component, the light emitting element, the light receiving element, and the like can be constantly maintained high.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a transmitting / receiving optical module according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a pattern of two 8-division photodiodes provided on a photodiode IC in the transmission / reception optical module according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a transmitting / receiving optical module according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a conventional transmitting / receiving optical module.

[Explanation of symbols]

1, 21 Ceramic substrate 2, 22, 23 Photodiode IC PD1, PD2, PD11, PD12 Photodiode 3 Micro prism 4, 24 Photodiode 5, 25 Semiconductor laser 8, 26 Package 9, 28 Condenser lens 10, 29 Optical fiber 11 , 30 Optical fiber fixing part 12, 31 Servo system 27 Hologram

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G02B 6/34 H01L 31/0232 H01S 3/18 H04B 10/24

Claims (11)

[Claims] 1. A substrate, a light emitting element and a light receiving element provided on the substrate, a condenser lens for condensing transmission signal light or reception signal light, and transmission signal light emitted from the light emitting element. And an optical component for causing the received signal light emitted from the one end face of the optical transmission line to be incident on the light receiving element, and at least the condensing light. A transmission / reception optical module, wherein a lens is configured to be movable with respect to the optical transmission line fixed to the optical transmission line fixing portion. 2. The whole of the substrate, the light emitting element, the light receiving element, the condenser lens and the optical component are integrally moved with respect to the optical transmission line according to the received signal light. The transmitting / receiving optical module according to claim 1. 3. The base, the light emitting element, the light receiving element and the optical component are fixed to the optical transmission line,
The transmitting / receiving optical module according to claim 1, wherein the condenser lens is moved with respect to the optical transmission line in accordance with the received signal light. 4. The transmission / reception optical module according to claim 1, wherein the base is a base having a high-frequency transmission line. 5. The transmission / reception optical module according to claim 1, wherein the light emitting element, the light receiving element, and the optical component are sealed by a package, and the condenser lens is attached to the package. 6. The transmission / reception optical module according to claim 1, wherein another substrate is provided on the substrate, and the light emitting element and the light receiving element are provided on the other substrate. 7. The transmission / reception optical module according to claim 6, wherein the another substrate is a semiconductor substrate, and the light receiving element is a photodiode provided on the semiconductor substrate. 8. The transmitting / receiving optical module according to claim 1, wherein the light emitting element is a semiconductor laser. 9. The transmission / reception optical module according to claim 1, wherein the optical component is a prism. 10. The transmitting / receiving optical module according to claim 1, wherein the optical component is a hologram. 11. The transmission / reception optical module according to claim 1, wherein the optical transmission line is an optical fiber.