JP2003014995A - Optical transmission module and optical transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission module which can be realized at a low cost without requiring complicated adjustment of the optical axis. SOLUTION: A sheet-type polymer optical waveguide 14 is formed on a substrate 12, and a transparent electrode layer 16 as an anode, an organic compound layer 18 containing a light-emitting layer, and a metal electrode layer 20 as a cathode are successively deposited by vapor deposition or the like on one end of the polymer optical waveguide 14 to form an organic electroluminescence(EL) element 22, which is used as a light source. Thus, the optical waveguide and the light source (organic EL element) can be easily coupled without requiring complicated adjustment of the optical axis or fabrication of the end face of the optical waveguide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission module and an optical transceiver, and more particularly to an optical transmission module and an optical transceiver that transmit light by introducing the light into an optical waveguide provided on a substrate.

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet and the progress of semiconductor integrated (LSI) technology, there is an increasing demand for higher speed and larger capacity of information processing devices. Terra (10
¹² ) In next-generation information processing equipment such as bit-level ATM switches and massively parallel computers, signal wiring (so-called interconnection) between devices, boards within devices, chips, etc. becomes a bottleneck for improving system performance. It is said. In order to solve this future problem, attention has been paid to optical interconnection utilizing the high speed of light.

For the purpose of this optical parallel processing / optical interconnection, a surface emitting LED and a surface emitting semiconductor laser (VCSEL: Vertical-Cavity Surface-Emitting) are used.
An optical transmission module has been proposed in which a semiconductor light emitting device such as a laser) and a sheet-shaped optical waveguide are combined.

An example of this optical transmission module is shown in FIG. The optical transmission module 50 shown in FIG. 7 has AlN (aluminum nitride) on which a plurality of IC chips 52 for signal transmission / reception (in the example of FIG. 7, eight IC chips for transmitting / receiving signals for 5 channels each) are mounted. A plurality of channels (10 channels in the example of FIG. 7) of VCSELs 56 are mounted on a wiring board 54 such as a multilayer wiring board. This VCS
The EL 56 is a sheet-shaped optical waveguide in which the one end surface 58A of the polymer optical waveguide film 58 having a plurality of channels (20 channels in the example of FIG. 7) is subjected to a mirror processing of 45 degrees and is passively coupled to the polymer optical waveguide film 58. Has been done.

The other end of the polymer optical waveguide film 58 is
It is coupled to the BF connector interface 62 in the BF connector receptacle 60. A BF connector plug 66 of a plurality of channels (20 channels in the example of FIG. 7) connected to an optical fiber array 64 composed of a plurality of optical fibers for performing communication of a plurality of channels is fitted into the BF connector receptacle 60. By VC
The SEL 54 is coupled to the optical fiber array 64 via the polymer optical waveguide film 58, the BF connector receptacle 60, and the BF connector plug 66 to enable optical communication.

[0006]

However, in the combination of the semiconductor light emitting device and the optical waveguide as described above, the optical waveguide is individually provided for each semiconductor light emitting device so that light can be efficiently input / output to / from the optical waveguide. It is necessary to precisely adjust the position (optical axis adjustment) and fix it with solder, UV effect adhesive, etc. to prevent the optical axis from shifting with time, which hinders cost reduction. Was there.

Further, as in the example of FIG. 7, one end surface 58A of the polymer optical waveguide film 58 is mirror-processed at 45 degrees, so that the end portion of the optical waveguide on the side for inputting / outputting light to / from the semiconductor light emitting element is processed. It was necessary to reduce the cost.

Further, in a semiconductor light emitting device, it is difficult to arrange a plurality of semiconductor light emitting elements in an array form to uniformly emit light, and in the example of FIG. 7 as well, two 20-channel polymer optical waveguide films 58 are arranged. On the other hand, since four VCSELs 54 of 10 channels are used side by side, a tact time is required in the mounting process, which hinders cost reduction.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical transmission module and an optical transceiver that can be realized at low cost without requiring complicated optical axis adjustment.

[0010]

In order to achieve the above object, the invention according to claim 1 includes a substrate having an optical waveguide formed on the surface thereof, and an organic material laminated on the optical waveguide of the substrate. And a light-emitting element used.

According to the first aspect of the invention, for example, a transparent electrode layer acting as an anode, a light emitting layer emitting light by applying a voltage, and an electrode acting as a cathode are provided on the optical transmission line provided on the substrate. Light emitting elements using organic materials are laminated by sequentially stacking layers on the optical transmission path by vapor deposition, and the light output from the light emitting elements is introduced into the optical waveguide, To transmit.

By using the light emitting element formed by laminating on the optical waveguide as a light source in this way, the optical waveguide and the light source can be easily coupled without requiring complicated optical axis adjustment and processing of the end surface of the optical waveguide. can do. Further, since the light emitting element may be laminated on the optical waveguide by vapor deposition or the like, the fixing technique which has been conventionally required is not necessary and the light emitting element can be easily patterned on the optical waveguide, and a plurality of light emitting elements can be formed. It can be monolithically integrated with the optical waveguide and the substrate. As a result, the mounting process of the optical transmission module can be significantly shortened and the cost can be reduced.

The invention described in claim 2 is characterized in that, in the invention described in claim 1, it further comprises a photodetector laminated on the optical waveguide of the substrate.

According to the second aspect of the present invention, for example, a transparent electrode layer acting as an anode, a photodetecting layer for detecting light incident by a photoelectric effect, and an electrode acting as a cathode are provided on the optical transmission line. The photodetector is laminated by sequentially laminating layers on the optical transmission line by vapor deposition or the like. That is, the light transmission module is a so-called total module capable of detecting the light output from the light emitting element and transmitted through the optical waveguide by the photodetector, and capable of transmitting and receiving light.

By stacking the photodetectors on the optical waveguide in this way, similar to the light emitting device described in claim 1, complicated optical axis adjustment and processing of the end face of the optical waveguide are not required. , The optical waveguide and the photodetector can be easily coupled. Further, since the photodetector may be laminated on the optical waveguide by vapor deposition or the like, there is no need for immobilization technology, and the photodetector can be easily patterned on the optical waveguide, and a plurality of photodetectors can be monolithically formed. Can be accumulated. As a result, the so-called total module mounting process can be significantly shortened and the cost can be reduced.

In order to carry out light transmission with high efficiency, the optical waveguide is a polymer optical waveguide and the light emitting element is an organic electroluminescent element as described in claim 3. Good to do.

According to a fourth aspect of the present invention, a substrate having a Y-branched Y-branch optical waveguide formed on the surface thereof and a Y-branch of the substrate are provided.
A light emitting element using an organic material laminated on one of the Y-branched optical waveguides, and a photodetector for detecting light laminated on the other of the Y-branched optical waveguides of the substrate, It is characterized by having.

According to the third aspect of the present invention, a so-called optical transceiver is formed by stacking a light emitting element on one of the branched ones and a photodetector on the other branched one on the Y-branch optical waveguide provided on the substrate. Is configured. By thus forming the light emitting element and the photodetector by stacking them on the Y-branch optical waveguide, complicated optical axis adjustment and Y adjustment can be performed as in the first and second embodiments.
The Y-branch optical waveguide and the light emitting element and the photodetector can be easily coupled without the need for processing the end face of the branched optical waveguide. Further, since the light emitting element and the photodetector may be formed by stacking them by vapor deposition or the like, a fixing technique is not necessary and the light guide element can be easily patterned on the optical waveguide. The detector can be monolithically integrated. As a result, the mounting process of the optical transceiver can be significantly shortened and the cost can be reduced.

In order to perform optical transmission with high efficiency, the optical waveguide may be a polymer optical waveguide and the light emitting element may be an organic electroluminescent element. Good to do.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example of an embodiment according to the present invention will be described in detail with reference to the drawings. 1 and 2 show an optical transmission module to which the present invention is applied.

As shown in FIGS. 1 and 2, in the optical transmission module 10, two sheet-shaped polymer optical waveguides 14 each having a width of about 10 μm are arranged side by side on a substrate 12, and the polymer optical waveguides 14 are arranged. On one end of each, a transparent electrode layer 16 as an anode, an organic compound layer 18 including a light emitting layer,
And an organic electroluminescence (EL) element 22 formed by sequentially stacking a metal electrode layer 20 as a cathode.
Is provided. The transparent electrode layer 16, the organic compound layer 18, and the metal electrode layer 20 are the first electrode layer, the light emitting layer, and the second electrode layer.
The organic EL element 22 corresponds to the light emitting element of the present invention.

It should be noted that in the present embodiment, 2 is formed on the substrate 12.
The case where one polymer optical waveguide 14 is provided will be described as an example, but the number of polymer optical waveguides 14 is not limited to this, and one or three or more polymer optical waveguides 14 may be provided. Also,
The parts of the optical transmission module 10 other than the above may be the same as those of the conventional general optical transmission module, and thus the description thereof will be omitted.

Each constituent element will be described in detail below.

As the substrate 12, a glass substrate or a plastic substrate can be used. The substrate 12 is required to have heat resistance, dimensional stability, solvent resistance, electric insulation, workability, low air permeability, low hygroscopicity, etc. as general substrate characteristics.

The polymer optical waveguide 14 is composed of a multi-channel polymer optical waveguide film, and is formed as a thin film on the order of several μm in order to maintain signal quality. The polymer optical waveguide 14 as described above can be formed by processing a sheet-shaped material such as PMMA (polymethylmethacrylate) or polyimide using a conventionally known photolithography technique and fine processing technique.

The transparent electrode layer 16 has a thickness of 400 nm to 700 n.
In the visible light wavelength range of m, it is preferable that the light transmittance is at least 50% or more, and preferably 70% or more. Examples of the material for forming the transparent electrode layer 16 include compounds known as transparent electrode materials such as tin oxide, indium tin oxide (ITO), and indium zinc oxide.
A thin film of a metal having a large work function such as gold or platinum may be used. Further, it may be an organic compound such as polyaniline, polythiophene, polypyrrole or their derivatives. In this embodiment, ITO is used. The transparent conductive film is described in detail in “New Development of Transparent Conductive Film” supervised by Yutaka Sawada, published by CMC (1999), and can be applied to the present invention.

The transparent electrode layer 16 can be patterned on the polymer optical waveguide 14 by a known method such as vacuum deposition or sputtering using a mask.

The organic compound layer 18 may have a single-layer structure composed of only a light emitting layer, or other layers such as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer in addition to the light emitting layer. It may be a laminated structure having appropriately.

As a concrete constitution of the organic compound layer 18 (displayed including electrodes), anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode, anode / light emitting layer /
Examples include electron transport layer / cathode, anode / hole transport layer / light emitting layer / electron transport layer / cathode, and the like. Further, a plurality of light emitting layers, hole transport layers, hole injection layers, and electron injection layers may be provided. In this embodiment, the anode / hole transport layer /
The structure of the light emitting layer / electron transporting layer / cathode was adopted.

Each layer can be formed by sequentially forming thin films of low molecular weight organic materials from the layer on the transparent electrode layer 16 side by vapor deposition or the like and stacking them. At this time, patterning can be easily performed by using a vapor deposition mask.

The organic compound layer 18 is the same as the organic compound layer of a conventionally known organic EL element, and the constituent material, forming method, and layer thickness of each layer constituting the organic compound layer are the same as those of the conventional one. The thing can be applied suitably.

Therefore, the light emitting material of the light emitting layer is not particularly limited as long as it is a compound capable of emitting light (a compound that emits fluorescence), and can be appropriately selected according to the purpose. As a light emitting material for the light emitting layer, Alq ₃ (aluminum triquinolinol complex), which is a typical example, was used.

The metal electrode layer 20 is made of an alkali metal such as Li or K, which has a low work function because of its excellent electron injection property, Mg,
Alkaline earth metals such as Ca and stable A that is not easily oxidized
It is preferably composed of a cathode material such as g or Al.
Two or more kinds of cathode materials may be combined in order to achieve both storage stability and electron injection property in the cathode. In the present embodiment, Mg / Al is used in combination.

Like the transparent electrode layer 16, the metal electrode layer 20 can also be patterned on the organic compound layer 18 by a known method such as vacuum deposition and sputtering using a mask.

With the above configuration, in the optical transmission module 10, the transparent electrode layer 1 of the organic EL element 22 is formed.
When a voltage is applied between 6 and the metal electrode layer 20 based on a signal to be transmitted (transmission signal), the light emitting layer of the organic compound layer 18 emits light in response to the voltage application. The voltage applied at this time may be a DC voltage (which may include an AC component if necessary) or a pulse voltage.

Of the emitted light, the transparent electrode layer 1
The light traveling to 6 passes through the transparent electrode layer 16 as it is, and the light traveling to the metal electrode layer 20 is reflected by the metal electrode layer 20 to the transparent electrode layer 16 by the metal electrode layer 20 functioning as a total reflection layer. It advances and penetrates the transparent electrode layer 16. That is, in the organic EL element 22, almost all the emitted light can be extracted to the transparent electrode layer 16 side. The light transmitted through the transparent electrode layer 16 is introduced into the inside of the polymer optical waveguide 14 from the upper surface thereof and is transmitted inside the polymer optical waveguide 14. Therefore, in the light transmission module 10, almost all the light based on the transmission signal emitted in the light emitting layer of the organic EL element 22 is introduced into the polymer optical waveguide 14 with a low light amount loss,
Can be transmitted.

As described above, by using the organic EL element 22 instead of the conventional semiconductor light emitting element as the light source of the optical transmission module, the complicated optical axis adjustment and the processing of the end face of the optical waveguide, which are conventionally required, are unnecessary. The optical waveguide and the light source (organic EL element) can be easily combined.

Further, since the organic EL element 22 can be formed by sequentially laminating each layer by vapor deposition or the like, the fixing technique which has been conventionally required is not necessary, and when vapor deposition, a vapor deposition mask is used. It can be easily patterned on the optical waveguide by using it. For example, a plurality of organic EL elements can be formed integrally with the optical waveguide and the substrate by simultaneously patterning elements for 100 channels or more in one process. , That is, they can be monolithically integrated. As a result, the mounting process of the optical transmission module can be significantly shortened and the cost can be reduced.

Further, generally, the light emitting layer of the organic EL element 22 represented by Alq3 has a wavelength band (500
Many materials emit light with high efficiency at
A POF (Plastic Optical Fiber) using a polymer material typified by PMMA used for the polymer optical waveguide 14.
r: plastic optical fiber) has the lowest propagation loss of 100 db / cm in the wavelength band of 550 to 600 nm as shown in the propagation loss spectrum of FIG. In addition,
3A and 3B are experimental values and theoretical values of the propagation loss spectrum of the perfluorinated POF, and the perfluorinated type has a lower transmission loss than the polymer type, but is expensive, There is a cost disadvantage.

Therefore, the use of the organic EL element 22 as a light source is also suitable for highly efficient optical transmission in the polymer optical waveguide 14. By actually driving the organic EL element 22 created as described above, theoretically, 1
It was possible to confirm a transmission rate of 100 Mbps or more at a drive voltage of 0V.

In the above description, the case where only the low molecular weight organic material is used for the organic compound layer has been described, but a high molecular weight material may be used. For example, after patterning the transparent electrode layer 16, MEH-PPV (soluble polyphenylene vinylene derivative) which is a π-conjugated polymer, which is a typical polymer, is patterned by spin coating or inkjet to form an organic compound layer. Alternatively, the metal electrode layer 20 may be formed thereon.

In the above description, the optical transmission module for transmitting light has been described as an example, but the present invention is not limited to this, and may be configured as follows.

For example, as shown in FIG. 4, the polymer optical waveguide 14 is formed on the polymer optical waveguide 14 on the glass substrate 12 in the same manner as the organic EL element 22.
The transparent electrode layer 30 as an anode is patterned on the above, and a so-called laminated type photodetector 36 is formed by laminating a photodetection layer 32 and a metal electrode layer 34 as a cathode by vapor deposition or the like. The so-called total module capable of detecting the light transmitted through the polymer optical waveguide 14 by the photodetector 36 and transmitting and receiving the light may be used.

The photodetection layer 32 of this total module
Is called the photoconductive effect, which is one of the internal photoelectric effects.
It is generally formed by stacking semiconductor layers (or insulating layers) by utilizing the property that electric conductivity increases when light is irradiated on a semiconductor (or an insulator). The light detection layer 32 is
It may be a polycrystalline semiconductor or one using an organic layer as in the light emitting layer.

The photoconduction effect occurs because electrons are excited from a valence band or an impurity level by light absorption and carriers of free electrons or holes are generated, and a photocurrent flows when a voltage is applied. By monitoring this photocurrent, the light transmitted through the polymer optical waveguide 14 can be detected and the transmission signal can be taken out.

The photodetection layer 32 may be the same as the conventionally known photodetection layer, and the constituent material of each layer constituting the photodetection layer,
As for the forming method and the layer thickness, the same methods as in the related art can be appropriately applied. In this example, as an example, FIG.
As shown in, the CuPc is formed in order from the transparent electrode layer 16 side.
(Copper phthalocyanine) layer 32A and PTCBI (3,4,9,10
-Perylene tetracarboxylic acid bis-benzimidazole) layers 32B are alternately laminated in three layers, and further B
The photodetection layer 3 is formed by laminating the CP (pasoku broin) layer 32C.
Formed 2.

As described above, the photodetector 36 is a laminated type similar to the organic EL element 22 described above, so that the polymer can be easily polymerized without requiring complicated optical axis adjustment and processing of the end face of the optical waveguide. The optical waveguide 14 and the photodetector 36 can be coupled. Further, since each layer may be laminated in order by vapor deposition or the like, a fixing technique is not necessary and the photodetector 36 is monolithic because it can be easily patterned on the optical waveguide by using a vapor deposition mask or the like. Can be accumulated. As a result, the mounting process of the total module can be shortened and the cost can be reduced.

Further, for example, as shown in FIG.
A so-called Y-branch optical waveguide 40 whose one end is branched in two directions is provided on the two, and the branched one is the organic EL element 22 in the same manner as above, and the other is the laminated type photodetector in the same manner as above. By providing 36, a so-called optical transceiver can be easily realized in a monolithic manner.

[0049]

As described above, the present invention has an excellent effect that it is possible to provide an optical transmission module which does not require complicated optical axis adjustment and can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an optical transmission module according to the present embodiment.

FIG. 2 is a perspective view showing a configuration of an optical transmission module according to the present embodiment.

FIG. 3 is a graph showing general propagation loss spectra of PMMA-based and perfluorinated POF.

FIG. 4 is a cross-sectional view showing the configuration of an optical transmission module provided with a laminated photodetector according to another embodiment.

5 is a cross-sectional view showing an example of the stacked photodetector of FIG.

FIG. 6 is a top view showing a configuration of an optical transmission module provided with a Y-branch optical waveguide according to another embodiment.

FIG. 7 is a configuration diagram of a conventional optical transmission module.

[Explanation of symbols]

10 Optical transmission module 12 substrates 14 Polymer optical waveguide 16 Transparent electrode layer 18 Organic compound layer 20 Metal electrode layer 22 Organic EL element 30 transparent electrode layer 32 light detection layer 34 metal electrode layer 36 Photodetector 40 Y-branch optical waveguide

Claims (5)

[Claims] 1. An optical transmission module comprising: a substrate having an optical waveguide formed on a surface thereof; and a light emitting element using an organic material laminated on the optical waveguide of the substrate. 2. The optical transmission module according to claim 1, further comprising a photodetector laminated on the optical waveguide of the substrate. 3. The light transmission module according to claim 1, wherein the optical waveguide is a polymer optical waveguide, and the light emitting element is an organic electroluminescence element. 4. A substrate having a Y-branched Y-branched optical waveguide formed on a surface thereof, and a light-emitting element using an organic material laminated on one of the Y-branched optical waveguides of the substrate, An optical transceiver comprising: a photodetector that detects light stacked on the other of the Y-branched optical waveguides on the substrate. 5. The optical transceiver according to claim 4, wherein the Y-branch optical waveguide is a polymer optical waveguide, and the light emitting element is an organic electroluminescence element.