JP2008170776A - Optical transmitter-receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and high-quality optical transmitter-receiver. <P>SOLUTION: The optical transmitter-receiver is constituted by optically coupling a light emitting element, a light receiving element and an optical waveguide having a core/clad structure. The optical transmitter-receiver is characterized in that: the light emitting element and the light receiving element have constitution where the elements are all coated with a coating part core composed of a core material for forming the optical waveguide and the outside of the coating part core is coated with a coating part clad composed of a clad material for forming the optical waveguide; and the coating part core with which each element is coated and the core of the optical waveguide are integrally formed while the coating part clad and the clad of the optical waveguide are integrally formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical transmission / reception device formed by coupling a light emitting element, a light receiving element, and an optical waveguide by passive alignment. The optical transmission / reception apparatus of the present invention is used in, for example, high-speed communication devices such as servers, optical wiring in automobiles, and small electronic devices such as mobile phones.

  In recent years, optical wiring is being applied to high-speed communication devices such as servers, wiring in automobiles, and small electronic devices such as mobile phones. These devices are becoming smaller and lower in cost, and accordingly, optical transmission / reception devices such as optical communication modules and optical transmission / reception modules are strongly demanded for reduction in size and cost. A light emitting diode (LED) or a surface emitting laser (VCSEL) is used as a light emitting element used in the optical transceiver. A photodiode (PD) is used as the light receiving element. As the optical waveguide, a fiber type or a sheet type waveguide is used, and the material includes quartz glass, polymer, and the like.

In an optical transmission / reception apparatus, various methods and structures have been conventionally studied for coupling a light emitting element, a light receiving element (hereinafter sometimes referred to as a light receiving / emitting element) and an optical waveguide (for example, (See Patent Documents 1 to 6.)
In Patent Document 1, as shown in FIG. 1, a VCSEL 4 is mounted in a direction perpendicular to a printed circuit board 5, and then an optical waveguide 1 provided with a mirror 6 for converting the optical path to a right angle is prepared. A method of aligning and fixing the optical axis to the VCSEL 4 mounted on the printed circuit board 5 is disclosed. In FIG. 1, reference numeral 2 denotes an IC, and 3 denotes a light emitting portion. Right-angle conversion of the optical path is achieved by forming a 45 ° mirror on the optical waveguide by cutting or laser processing.
In Patent Document 2, the output of light emitted from a light emitting device is monitored by a light receiving device at a light emitting end of the waveguide, and the light emitting device, the light receiving device, and the waveguide are relatively moved and fixed so that the output is maximized. A technique is disclosed.
Patent Document 3 discloses a structure in which a light emitting element and an optical waveguide are coupled with a fluid optical waveguide material. A dispenser is used to apply the flowable material. The produced optical waveguide has a core / cladding structure. The core diameter of the optical waveguide is larger than the light emitting part diameter.
Patent Document 4 discloses that a viscous material is applied by a dispenser to form an optical waveguide. The produced optical waveguide has a core / cladding structure.
Patent Document 5 discloses a structure in which a plurality of light emitting / receiving elements are coupled by an optical waveguide coated with a dispenser. The produced optical waveguide has a core / cladding structure. The core / cladding diameter of the optical waveguide is larger than the light emitting portion diameter.
Patent Document 6 discloses that an optical waveguide is formed by applying a viscous material with a dispenser. The produced optical waveguide has a core / cladding structure.
JP 2006-11179 A JP 2005-202025 A JP-A-9-243858 JP-A-6-82643 US Pat. No. 6,516,121 US Pat. No. 5,534,101

However, the above-described prior art has the following problems.
In the method disclosed in Patent Document 1, it takes much time and cost to form a 45 ° mirror, which is a problem. Further, there is a problem that the coupling efficiency between the VCSEL and the optical waveguide deteriorates due to diffusion on the 45 ° mirror surface and extension of the optical path length. Another problem is that much time and cost are required for alignment of the optical axis between the VCSEL and the optical waveguide.
The method disclosed in Patent Document 2 takes a very long time to adjust the optical path. In particular, when trying to connect a plurality of waveguides, the efficiency is low, which causes an increase in cost.
In Patent Document 3, there is no description that the entire light emitting element is covered with an optical waveguide material.
Patent Document 4 does not describe the coupling with light receiving and emitting elements.
In Patent Document 5, there is no description that the entire light emitting element is covered with an optical waveguide material.
Patent Document 6 does not describe the coupling with light receiving and emitting elements.
Note that this is also the case with respect to light-emitting elements other than VCSELs and the coupling of light-receiving elements and optical waveguides.

As described above, the conventional technique cannot provide a low-cost and high-quality optical transceiver.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a low-cost and high-quality optical transceiver.

In order to achieve the above object, the present invention provides an optical transceiver in which a light emitting element, a light receiving element, and an optical waveguide having a core / cladding structure are optically coupled.
The light emitting element and the light receiving element have a structure in which the entire element is covered with a covering core made of a core material that forms the optical waveguide, and the covering core that covers each element and the core of the optical waveguide are integrally formed. An optical transmission / reception device is provided.

Further, the present invention provides an optical transceiver in which a light emitting element, a light receiving element, and an optical waveguide having a core / cladding structure are optically coupled.
A structure in which a light emitting element and a light receiving element are covered with a covering core made of a core material forming an optical waveguide, and the outer surface of the covering core is covered with a covering cladding made of a cladding material forming an optical waveguide. An optical transmission / reception apparatus comprising: a covering core that covers each element; and a core of an optical waveguide formed integrally, and a covering cladding and an optical waveguide cladding formed integrally I will provide a.

  In the optical transmission / reception apparatus of the present invention, it is preferable that the bonding wire coupled to the light emitting element and the light receiving element is covered with the element by the covering core and the covering clad.

  In the optical transceiver of the present invention, it is preferable that the core material forming the optical waveguide is one resin selected from the group consisting of epoxy resins, acrylic resins, and polyimide resins.

  In the optical transceiver of the present invention, it is preferable that the submount on which the light emitting element and the light receiving element are mounted is mounted on the substrate, and the light emitting direction of the light emitting element and the light receiving direction of the light receiving element are oriented parallel to the substrate surface.

  In the optical transceiver of the present invention, the light emitting element is preferably a surface emitting laser.

The optical transceiver of the present invention covers the entire light emitting element and the light receiving element with a covering core made of a core material that forms the optical waveguide, and the covering core and the core of the optical waveguide are integrally formed. Optical path adjustment work such as optical axis alignment can be omitted, and a high-quality optical transceiver can be easily manufactured. Therefore, according to the present invention, a low-cost optical transceiver can be provided.
Moreover, sufficient protection of the bonding wire can be achieved by covering the bonding wire bonded to the light emitting / receiving element.
In the optical transceiver of the present invention, the entire light emitting element and the light receiving element are covered with a covering core made of a core material forming the optical waveguide, and the covering core and the core of the optical waveguide are integrally formed. Therefore, the mounting strength of these light emitting / receiving elements on the substrate can be increased.
In addition, since the light emitting / receiving element and the optical waveguide can be coupled without using a mirror, the size and thickness can be further reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
2A and 2B are diagrams showing an embodiment of the optical transceiver of the present invention. FIG. 2A is a side sectional view of the optical transceiver 10 and FIG. 2B is a plan view. In the figure, reference numeral 10 is an optical transceiver, 11 is a VCSEL that is a light emitting element, 12 is a PD that is a light receiving element, 13 is an optical waveguide, 14 is a printed circuit board, 15 is a submount substrate, 16 is a core, and 17 is a lower cladding. , 18 is an upper cladding, 19 is a coating core, and 20 is a coating cladding.

  The optical transmission / reception apparatus 10 of this embodiment is an optical transmission / reception apparatus in which the VCSELs 11 and PD12 that are light receiving and emitting elements and the optical waveguide 13 having a core / cladding structure are optically coupled. The covering core 19 and the covering cladding 20 are integrally formed with the core 16 and the claddings 17 and 18 of the optical waveguide.

  In the optical transceiver 10 of the present embodiment, the VCSEL 11 and the PD 12 are mounted on the side surfaces of the quadrangular columnar submount substrate 15, and the bottom surface of the submount substrate 15 is fixed to the surface of the printed circuit board 14, thereby The light emitting direction and the light receiving direction of the PD 12 are parallel to the surface of the printed circuit board 14.

  The material of the core 16 and the covering core 19 of the optical waveguide 13 is made of a transparent synthetic resin, and the materials of the claddings 17 and 18 and the covering cladding 20 of the optical waveguide are transparent with a refractive index lower than that of the core material. Made of synthetic resin.

  In the present embodiment, as shown in FIG. 3, the VCSEL 11 and the PD 12 are entirely covered with the covering core 19, and further, the entire outside of the covering core 19 is covered with the covering cladding 20. Further, the bonding wires 21 for wiring the VCSEL 11 and the PD 12 are also covered with the covering core 19. FIG. 3 shows the coated state of the VCSEL 11, but the same applies to the PD 12. In FIG. 3, reference numeral 21 denotes a bonding wire, 22 denotes a cathode of the VCSEL 11, and 23 denotes a light emitting part.

  In the present embodiment, the covering core 19 entirely covers the VCSEL 11, and a part of the covering core 19 extends and is integrally connected to the core 16 of the optical waveguide 13. The covering clad 20 also completely covers the outside of the covering core 19, and a part of the covering clad 20 extends and is integrally connected to the clad 17 of the optical waveguide 13.

  As shown in FIG. 3, the feature of this embodiment is that the entire VCSEL 11 and PD 12 that are light emitting and receiving elements are covered with a core material and a clad material. By adopting such a structure, it is possible to realize the optical transceiver 10 which is inexpensive and has high coupling efficiency between the VCSEL 11 and the PD 12 and the optical waveguide 13.

  In addition, there is an effect that the mounting strength of the VCSEL 11 and the PD 12 that are light emitting / receiving elements on the printed circuit board 14 is increased. If only the vicinity of the light receiving and emitting part is covered with the core / cladding material, light leakage is large and it is difficult to realize high optical coupling efficiency. On the other hand, in the structure that covers the entire element as in the present embodiment, high optical coupling efficiency can be realized at a low manufacturing cost without finely aligning the core material, the clad material, and the light receiving and emitting part. In particular, by adopting a structure in which the entire element is covered with a core material, the tolerance of optical axis alignment is further increased, and an optical transceiver can be realized at a lower manufacturing cost.

  The core material and the clad material are made of a polymer material, and a material having a high transmittance in the wavelength band of the light source to be used can be used. For example, when a VCSEL having an emission wavelength of 850 nm is used as the light emitting element, a polymer material such as an acrylic resin, an epoxy resin, or a polyimide resin can be used. In addition, these materials include a thermosetting type, a photocurable type (particularly preferably an ultraviolet curable type), and a two-component reaction curable type, and any of these may be used.

Patent Documents 3 to 6 described above are inventions for solving the problem of cost reduction in Patent Documents 1 and 2, which are similar to the problems of the present invention at first glance. The disclosed technique and the technique of the present invention are completely different, and this point will be described below.
First, as for Patent Document 5, FIG. Comparison with 5 will be important. FIG. 5, reference numeral 39 denotes a part of the element 40, and the core material 71 of the connected optical waveguide is shown to be slightly wider at the connection interface, but has a considerably narrower diameter than the part indicated by reference numeral 39. Is clear. Therefore, as shown in FIG. 3 of this embodiment, the configuration of “covering the entire element with the core material and the clad material” is described in FIG. There is a clear difference from the example illustrated in FIG.
For Patent Document 3, a comparison with FIG. 19 or FIG. 21 will be important. In these, as in the above-mentioned Patent Document 5, the optical transmission line 40 or its core part 40a and the clad part 40b are much thinner than the optical / electronic integrated circuit 2 and are connected even if compared with the optical transmission line 21. It only spreads to the same extent near the interface and is basically thinner than that. Therefore, as shown in FIG. 3 of the present embodiment, there is a clear difference from the configuration in which the entire element is completely covered with the core material and the clad material.
Patent Document 6 and Patent Document 4 are only very similar in their manufacturing methods, and these prior arts describe the connection structure between the light emitting element / light receiving element and the core of the dispenser-drawn polymer optical waveguide. No.

  As shown in FIG. 4, a light emitting element such as a VCSEL 11 or an LED or a light receiving element such as a PD 12 generally has a structure having a cathode 22 or an anode on the same surface as the light emitting part 23 or the light receiving part. The anode or the cathode has a structure for conducting by wire bonding, and after the wire bonding, the bonding wire 21 needs to be protected. In this embodiment, sufficient protection of the bonding wire 21 can be achieved by completely covering the bonding wire 21 with the core material and the clad material.

Next, a method for manufacturing the optical transmission / reception apparatus 10 of this embodiment will be described with reference to FIG.
When manufacturing the optical transceiver 10 of this embodiment, first, the VCSEL 11 and the PD 12 are respectively mounted on the side surfaces of the submount substrate 15, and then the bottom surfaces of these submount substrates 15 are fixed at predetermined positions on the printed circuit board 14. At the time of fixing, the VCSEL 11 and the PD 12 and the printed board 14 are electrically connected.

  Next, a lower clad 17 is formed on the surface of the printed circuit board 14 at the position where the optical waveguide 13 is formed and below the light emitting / receiving elements 11 and 12. The lower clad 17 may be formed over the entire surface of the printed board 14. The lower clad 17 is formed by a method in which a resin solution obtained by heating and melting a thermoplastic resin is applied by a dispenser or the like. An uncured ultraviolet curable resin is applied to the surface of the printed circuit board 14 by a dispenser or the like, and then cured by irradiation with ultraviolet rays. The method of making it can be employ | adopted and can be suitably selected according to the resin material to be used.

  Next, the core material 26 is applied and cured so as to cover the entire VCSEL 11 and the PD 12, thereby forming the covering core 19 and the core 16 of the optical waveguide 13. The core material 26 can be applied by an inkjet method, application by a dispenser, or the like. For example, in the case of application by a dispenser, first, a light emitting portion of a light emitting element is manufactured. The method for curing the core material 26 is not particularly limited, but a thermosetting material or a photocurable material can be used. The shape of the core section can be adjusted by adjusting the time from application of the core material 26 to curing. Further, the core cross-sectional area can be adjusted by adjusting the discharge pressure and the sweep speed of the dispenser.

  When using an ultraviolet curable resin, as shown in FIG. 5A, the core 16 of the optical waveguide 13 is efficiently manufactured by following the curing light source 27 in accordance with the sweeping operation of the dispenser nozzle 25. can do. The amount of the core material 26 can be adjusted by adjusting the positions of the dispenser nozzle 25 and the light source 27 according to the sweep speed. When drawing the core 16 by a dispenser or an inkjet method, the height of the core 16 can be increased by overdrawing. However, when overlaid, an interface is formed between the first layer and the second layer, which may cause light scattering when performing optical transmission and may increase transmission loss.

  After the coating and curing process of the core material 26 described above, as shown in FIG. 5B, a covering core 19 that covers the entire VCSEL 11 and PD 12 is formed on the lower clad 17, and the covering core 19 is integrated with the covering core 19. The core 16 of the optical waveguide 13 connected to is formed.

Next, the upper cladding 18 is formed so as to surround the outer sides of the covering core 19 and the core 16 of the optical waveguide 13. The upper clad 18 may be formed so as to surround only the outer sides of the covering core 19 and the core 16 of the optical waveguide 13, or may be formed so as to cover the entire substrate surface after the core is formed. In either case, it can be formed using a technique similar to the technique for forming the cores 16 and 19 described above or the technique for forming the lower cladding 17 described above.
By forming the upper clad 18, the optical transceiver 10 of this embodiment shown in FIG. 2 is obtained.

  A submount substrate 15 shown in FIG. 6 was produced. The material of the submount substrate 15 was aluminum nitride. The submount substrate 15 has a quadrangular column shape, and a side electrode 29 and a bottom electrode 28 are formed. The material of these electrodes was a gold-tin alloy in consideration of the connection strength with the gold wire (bonding wire 21) when mounting the light emitting / receiving element.

  As shown in FIG. 6, the light emitting / receiving element was mounted on the side surface of the submount substrate 15. This mounting was performed with conductive silver paste and gold wire. A VCSEL 11 having an emission center wavelength of 850 nm was used as the light emitting element, and a PD 12 was used as the light receiving element. When the VCSEL 11 is directly mounted on a substrate, light is emitted perpendicular to the substrate surface. It is desirable to extend the optical waveguide in the horizontal direction with respect to the substrate because the space inside the apparatus can be used effectively. For this purpose, the emitted light is changed to a direction parallel to the substrate by a 45 ° mirror, or an optical waveguide is installed in the vertical direction and optically coupled, and then the optical waveguide is bent by 90 ° to the substrate. There is a way to make it horizontal. Both methods are not desirable because the volume of the optical coupling part increases. By using the submount substrate 15 to direct the radiated light of the VCSEL 11 horizontally with the substrate and further using the configuration of the optical waveguide of the present invention, it is possible to perform coupling in a smaller space and realize a compact optical transceiver.

  Next, the submount substrate 15 on which the VCSEL 11 and the PD 12 were mounted on the side surface was mounted on the printed circuit board 14. The submount substrate 15 was transported by vacuum tweezers and joined to the electrode pad of the printed circuit board 14 using a conductive silver paste.

Next, the optical waveguide 13 was produced. First, the lower clad material 17 was applied (see FIG. 7). Application was performed using a dispenser. As a resin for forming the lower clad 17, an ultraviolet curable epoxy resin was used. The viscosity of this epoxy resin is 1000 cps, and the refractive index after curing is 1.52. The diameter of the dispenser nozzle used at this time was 5 kgf / cm ² . After sweeping, it was allowed to stand for 10 minutes and cured by irradiating with ultraviolet rays having a wavelength of 365 nm. The illuminance of the irradiated ultraviolet light was 100 nW / cm ² . The width of the lower clad 17 after curing was about 0.8 mm and the thickness was 0.2 mm.

Next, the core material was applied using a dispenser (see FIG. 5A). As the resin for forming the core, an ultraviolet curable epoxy resin was used. The viscosity of this epoxy resin is 5000 cps, and the refractive index after curing is 1.57. The nozzle diameter of the dispenser used here was 0.05 mm in inner diameter. The sweep speed of the dispenser was 5 mm / s. The discharge pressure of the dispenser was 5 kgf / cm ² . In addition, an emission port of an ultraviolet lamp (light source 27) having a wavelength of 365 nm is placed at a position 20 mm behind the dispenser, and the sweep of the dispenser nozzle 25 is followed at the same speed. I did it. The ultraviolet irradiation condition was 100 mW / cm ² .

  When applying the core material 26, it started from the light emitting part 23 of the VCSEL 11, and after drawing a predetermined optical wiring pattern, it was swept to the PD light receiving part. First, in the VCSEL light emitting unit, a sufficient amount of core material was applied in a state where the sweeping of the dispenser nozzle was stopped so that the bonding wire connected to the entire CSEL element and the cathode completely entered the core material. After applying a sufficient amount of core material, sweeping of the dispenser nozzle was started and drawing of a predetermined optical wiring pattern was started. In addition, when coupled to the PD light receiving portion, application was performed by adjusting the sweep speed of the dispenser nozzle so that the entire PD element and the bonding wire 21 could be in the core material. In a predetermined optical wiring pattern portion between the VCSEL 11 and the PD 12, the core 16 of the optical waveguide 13 has a line width of 0.05 mm and a thickness of 0.03 mm.

Next, an upper cladding material was applied. Application was performed using a dispenser. As the resin for forming the upper clad 18, the same ultraviolet curable epoxy resin as that for the lower clad 17 was used. Its viscosity is 1000 cps and the refractive index after curing is 1.52. The diameter of the nozzle of the dispenser used at this time was 0.2 mm. The sweep speed of the dispenser was 5 mm / s. The discharge pressure of the dispenser was 5 kgf / cm ² . After sweeping, it was allowed to stand for 10 minutes and cured by irradiating with ultraviolet rays having a wavelength of 365 nm. The illuminance of the irradiated ultraviolet light was 100 mW / cm ² . The cured upper clad 18 completely covers the core 16 and has a structure suitable as the optical waveguide 13.

  A VCSEL driving circuit, a transimpedance amplifier, and a limiting amplifier were connected to the optical transceiver thus fabricated, and an optical transmission experiment was performed. When the bid error rate was measured using a commercially available digital data analyzer, it was driven for 4 hours at a driving speed of 1.0 GHz, and error-free was achieved. In addition, an image signal transmission experiment was performed using a commercially available sampling oscilloscope. The analog signal output from the CCD camera was digitally converted and serialized, and then transmitted by the LVDS method. Analog conversion, serialization, and LVDS compatible signal conversion were performed using a commercially available communication board. As a result of the experiment, it was possible to transmit the image of the CCD camera in real time and display it on the display.

It is a side view which shows the prior art example of an optical transmitter / receiver. It is a figure which shows one Embodiment of the optical transmitter / receiver of this invention, (a) is side sectional drawing of an optical transmitter / receiver, (b) is a top view. FIG. 3 is a side cross-sectional view of a main part of the optical transmission / reception device of FIG. 2. FIG. 3 is a perspective view illustrating a light emitting element used in the optical transmission / reception apparatus of FIG. 2. FIGS. 3A and 3B are diagrams illustrating a method for manufacturing the optical transceiver of FIG. 2, in which FIG. 3A is a side cross-sectional view showing a state when a core is formed, and FIG. It is a figure which shows the submount board | substrate which mounted the light emitting / receiving element used for the optical transmission / reception apparatus produced in the Example which concerns on this invention, (a) is a front view, (b) is a bottom view, (c) is a side view. (D) is a perspective view. It is side surface sectional drawing which shows the state after lower clad formation of the optical transmitter / receiver produced in the Example which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical transmitter / receiver, 11 ... VCSEL (light emitting element), 12 ... PD (light receiving element), 13 ... Optical waveguide, 14 ... Printed circuit board, 15 ... Submount substrate, 16 ... Core, 17 ... Lower clad, 18 ... Upper part Cladding, 19 ... covering core, 20 ... covering cladding, 21 ... bonding wire, 22 ... cathode, 23 ... light emitting part, 24 ... anode, 25 ... dispenser nozzle, 26 ... core material, 27 ... light source, 28 ... bottom electrode , 29 ... side electrodes.

Claims (6)

In an optical transceiver in which a light emitting element, a light receiving element, and an optical waveguide having a core / cladding structure are optically coupled,
The light emitting element and the light receiving element have a structure in which the entire element is covered with a covering core made of a core material that forms the optical waveguide, and the covering core that covers each element and the core of the optical waveguide are integrally formed. An optical transmitter / receiver characterized by the above. In an optical transceiver in which a light emitting element, a light receiving element, and an optical waveguide having a core / cladding structure are optically coupled,
A structure in which a light emitting element and a light receiving element are covered with a covering core made of a core material forming an optical waveguide, and the outer surface of the covering core is covered with a covering cladding made of a cladding material forming an optical waveguide. An optical transmission / reception apparatus comprising: a covering core that covers each element; and a core of an optical waveguide formed integrally, and a covering cladding and an optical waveguide cladding formed integrally .   The optical transmission / reception apparatus according to claim 1 or 2, wherein a bonding wire coupled to the light emitting element and the light receiving element is covered with the element by a covering core and a covering clad.   4. The light according to claim 1, wherein the core material forming the optical waveguide is one resin selected from the group consisting of an epoxy resin, an acrylic resin, and a polyimide resin. Transmitter / receiver.   5. The submount on which the light emitting element and the light receiving element are mounted is mounted on a substrate, and the light emission direction of the light emitting element and the light receiving direction of the light receiving element are oriented parallel to the substrate surface. An optical transceiver according to claim 1.   6. The optical transmitting / receiving apparatus according to claim 1, wherein the light emitting element is a surface emitting laser.

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