JP2009020425A - Optical waveguide holding member and optical transceiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide holding member which has an optical fiber disposed as an optical waveguide to suppress misalignment between optical centers of a printed board side and the optical waveguide holding member side due to temperature change, and to provide an optical transceiver. <P>SOLUTION: The optical transceiver 10 has the optical waveguide holding member 12 mounted on a printed board 11. A housing 12A of the optical waveguide holding member 12 is made of a clad material containing carbon nanotubes as a filler integrally with an element-side lens 12E and a fiber-side lens 12F. When the optical waveguide holding member 12 is bonded to the printed board 11, the element-side lens 12E faces a light emission/reception portion 13A of a photoelectric converting element 13 formed on the printed board 11. The coefficient of linear expansion of the housing 12A is decreased by the carbon nanotubes, so that the misalignment between the element-side lens 12E and light mission/reception portion 13A due to temperature change can be suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an optical waveguide holding member mounted on a printed circuit board of an optical transceiver that performs conversion between an electric signal and an optical signal, and an optical transceiver using the optical waveguide holding member.

Conventionally, communication using optical fibers has become mainstream due to the development of high-speed, large-capacity communication networks and communication control devices. For example, signals are transmitted and received by connecting a communication network such as the Internet to an information terminal installed in an office or home by an optical fiber. An optical transceiver capable of bidirectionally converting an electric signal and an optical signal is used at a connection portion between a personal computer and peripheral devices and an optical fiber (external optical fiber). Such an optical transceiver includes an optical waveguide formed between an external optical fiber and a photoelectric conversion element (see, for example, Patent Document 1).
JP 2001-05271 A

  In the optical transceiver as described above, an optical waveguide holding member for an optical waveguide is mounted on a printed circuit board on which a photoelectric conversion element is disposed. Usually, the printed circuit board is made of glass epoxy resin, while the optical waveguide holding member is made of olefin resin in order to ensure the function as a clad material. The optical path connection between the photoelectric conversion element arranged on the printed circuit board side and the optical waveguide arranged on the optical waveguide holding member side is such that the light receiving and emitting part of the photoelectric conversion element faces the end of the optical waveguide This is realized by matching each optical center. The positional accuracy between the optical centers is required to be ± several μm level.

  By the way, the temperature of the optical transceiver rises to about 80 to 90 ° C. during use. Further, the thermal expansion coefficients of the printed board and the optical waveguide holding member are different. For this reason, depending on the distance between the bonding position of the printed circuit board and the optical waveguide holding member and the respective optical centers, there is a possibility that the optical centers may be displaced due to thermal expansion. That is, if the distance between the bonding position of the printed circuit board and the optical waveguide holding member and each optical center is shifted by several μm or more due to thermal expansion, the performance of the optical transceiver may be greatly affected.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical waveguide holding member and an optical transceiver in which a positional shift due to a temperature change between optical centers on a printed circuit board side and an optical waveguide holding member side is suppressed.

  An optical waveguide holding member according to one aspect of the present invention is mounted on a printed circuit board of an optical transceiver that performs conversion between an electric signal and an optical signal, and between an external optical fiber and a photoelectric conversion element mounted or formed on the printed circuit board. An optical waveguide holding member for holding the optical waveguide, wherein a first connection portion that optically connects the first end of the optical waveguide to the light receiving and emitting portion of the photoelectric conversion element, and a second end of the optical waveguide A second connection portion that is optically connected to the external optical fiber, and the light that is formed between the first connection portion and the second connection portion while holding the first connection portion and the second connection portion. A housing for holding a waveguide, and the first connecting portion, the second connecting portion, and the housing are integrally formed of a clad material containing carbon nanotubes or carbon fullerenes.

  Moreover, you may provide the said 1st connection part and the said 2nd connection part with the lens integrally molded with the said 1st connection part and the said 2nd connection part.

  The length of the carbon nanotube may be equal to or shorter than the wavelength of the optical signal.

  An optical transceiver according to an aspect of the present invention includes a printed circuit board on which the photoelectric conversion element is mounted or formed, and any one of the optical waveguide holding members.

  According to the present invention, it is possible to provide a specific effect that an optical waveguide holding member and an optical transceiver can be provided in which a positional shift due to a temperature change between optical centers of the printed circuit board side and the optical waveguide holding member side is suppressed.

  Hereinafter, embodiments to which the optical waveguide holding member and the optical transceiver of the present invention are applied will be described.

  1A and 1B are diagrams showing an optical waveguide holding member and an optical transceiver according to the present embodiment. FIG. 1A is a perspective view showing the whole, and FIG. 1B is a perspective view showing only a printed circuit board.

  The optical transceiver 10 of this embodiment includes an optical waveguide holding member 12 mounted on a printed board 11. The optical waveguide holding member 12 is bonded to the printed board 11.

  The printed board 11 is formed by forming a copper wiring (not shown) on a glass epoxy resin board. A photoelectric conversion element 13 is formed on the printed board 11 as shown in FIG. The photoelectric conversion element 13 is connected to an IC or the like formed on the printed board 11 via a copper wiring (not shown). Note that the photoelectric conversion element 13 is formed so that the light emitting / receiving portion 13A is positioned substantially on the same plane as the upper surface of the printed board 11, but for the sake of convenience of description, the outline is shown by a solid line in FIG.

  2A and 2B are views showing a housing of the optical waveguide holding member according to the present embodiment, in which FIG. 2A is a perspective view showing a front surface, a plane surface, and a right side surface, and FIG. It is a perspective view shown.

  The optical waveguide holding member 12 has a housing 12A made of a clad material containing carbon nanotubes. This clad material is made of an olefin resin.

  The housing 12A includes an optical waveguide for transmitting an optical signal between an external optical fiber (not shown) connected to the connection portion 12B on the back side and the photoelectric conversion element 13 provided on the bottom side. It is a member to hold. The optical waveguide is formed on the optical waveguide forming surface 12C. The optical waveguide forming surface 12C is curved approximately 90 degrees from the upper surface side to the front side of the housing 12A, and has a three-dimensional shape corresponding to approximately ¼ of the outer peripheral surface of the cylindrical body. The connecting portion 12B is provided with pin holes on both sides for positioning the ferrule of the external optical fiber.

  As shown in FIG. 2A, a groove 12D is formed on the optical waveguide forming surface 12C, and the core member 14 (see FIG. 1) is injected into the groove 12D. A clad material film (not shown) is formed on the upper surface of the core member 14. Thus, an optical fiber is formed on the optical waveguide forming surface 12C. FIG. 1 shows a state in which eight core members 14 are formed.

  An element side lens 12E for transmitting and receiving an optical signal to and from the light emitting / receiving unit 13A of the photoelectric conversion element 13 is integrally formed at the bottom (portion on the bottom side) of the housing 12A, and the rear surface of the housing 12A In the connecting portion 12B), a fiber side lens 12F for transmitting / receiving an optical signal to / from an external optical fiber is integrally formed. The positions where the element side lens 12E and the fiber side lens 12F are formed are positions facing both ends of the core member 14.

  The element side lens 12E has, for example, a diameter of about 0.2 mm, and a gap between the light emitting / receiving portion 13A of the photoelectric conversion element 13 and the core member 14 in a state where the waveguide holding member 12 is bonded to the printed circuit board 11. This is an optically connected lens.

  There is a gap of, for example, about 500 μm between the core member 14 and the light receiving / emitting part 13A of the photoelectric conversion element 13, but the optical signal emitted from the core member 14 is condensed by the element side lens 12E and photoelectrically converted. The light is incident on the light emitting / receiving portion 13A of the element 13. The same applies to the reverse direction.

  Here, although described as the light emitting / receiving unit 13A, in reality, one of the pair of photoelectric conversion elements 13 shown in FIG. 1B receives photoelectric signals for receiving optical signals and converting them into electric signals. A light receiving portion is formed in this photoelectric conversion element. The other of the pair of photoelectric conversion elements 13 shown in FIG. 1B is a photoelectric conversion element for converting an electric signal into an optical signal and transmitting the light signal, and a light emitting portion is formed in this photoelectric conversion element. Is done. Here, the photoelectric conversion element 13 and the light emitting / receiving unit 13A are shown without any particular distinction.

  The fiber side lens 12F has a diameter of about 0.2 mm, and optically connects between an external optical fiber (not shown) and the core member 14 in a state where the waveguide holding member 12 is bonded to the printed circuit board 11. It is a lens to do.

  The fiber side lens 12 </ b> F is formed in the connection portion 12 </ b> B of the housing 12. Between the core member 14 and the fiber side lens 12F, and between the fiber side lens 12F and the external optical fiber, there are gaps of about 500 μm, for example, but the optical signal emitted from the core member 14 is The light is collected by the fiber side lens 12F and enters the external optical fiber. The same applies to the reverse direction.

  Here, the housing 12A is made of a clad material containing carbon nanotubes in an olefin resin. As the carbon nanotube, one having a length of about 800 nm and a diameter of 1 nm is used. The reason why the length is set to 800 nm is to suppress loss of an optical signal transmitted through the element side lens 12E and the fiber side lens 12F because the housing 12A is integrally formed with the element side lens 12E and the fiber side lens 12F. This is because the wavelength of the optical signal (laser light) is shorter than 800 nm to 1600 nm.

  The linear expansion coefficient of the olefin resin is about 70 ppm / ° C., whereas the linear expansion coefficient of the carbon nanotube is about 7 ppm / ° C.

  For this reason, the linear expansion coefficient of the housing 12A can be reduced by including the carbon nanotubes, and the temperature of the optical transceiver 10 is increased during use by optimizing the content ratio (weight ratio). In addition, it is possible to suppress the occurrence of positional deviation between the element side lens 12E and the light emitting / receiving unit 13A.

  The positional accuracy between the optical center of the element-side lens 12E and the optical center of the light emitting / receiving unit 13A is required to have a level of about ± 0.5 to 20 μm, for example. For this reason, the content rate of the carbon nanotube is, for example, the positional deviation due to the temperature rise is equal to or less than the above-described positional accuracy in consideration of the length from the fixed position of the optical waveguide holding member 12 to the printed board 11 to the element side lens 12E. (That is, it may be set to be within the allowable limit).

  The linear expansion coefficient of the printed circuit board 11 is about 14 ppm / ° C., the linear expansion coefficient of the core member 14 is about 70 ppm / ° C., and the linear expansion coefficient of the adhesive for bonding the optical waveguide holding member 12 to the printed circuit board 11 is about 70 ppm / ° C. For this reason, you may determine the content rate of a carbon nanotube in consideration of the linear expansion coefficient of these members.

  Conventionally, glass fibers or glass beads have been used as fillers in order to reduce the linear expansion coefficient of polymer materials such as olefin resins. However, since the optical signal is irregularly reflected due to the difference in refractive index between the glass fiber or glass bead and the polymer material, the housing in which the element side lens 12E and the fiber side lens 12F are integrally molded as in the present embodiment. Not suitable for 12A material.

  On the other hand, the present embodiment provides an optical waveguide holding member 12 and an optical transceiver 10 that use carbon nanotubes as fillers to prevent deterioration of optical characteristics and suppress performance degradation due to temperature changes. Can do.

  In the above, the case where the wavelength of the optical signal is 800 nm to 1600 nm has been described as an example. However, if the wavelength is shorter, carbon nanotubes having the wavelength or less may be used.

  In the above description, the optical waveguide holding member integrally formed with the clad material containing carbon nanotubes has been described. However, instead of or in addition to the carbon nanotubes, the clad material contains carbon fullerene and the optical waveguide. The holding member may be integrally formed. Since carbon fullerene has a diameter of about 0.7 nm and the linear expansion coefficient is substantially the same as that of carbon nanotubes, if carbon clad material is used instead of carbon nanotubes, carbon nanotubes are contained as described above. The same result as that obtained can be obtained.

  Moreover, although the form in which the photoelectric conversion element 13 was formed in the printed circuit board 11 was demonstrated above, you may comprise so that the photoelectric conversion element 13 produced separately from the printed circuit board 11 may be mounted.

  The optical waveguide holding member and the optical transceiver according to the exemplary embodiment of the present invention have been described above. However, the present invention is not limited to the specifically disclosed embodiment, and from the claims. Various modifications and changes can be made without departing.

It is a figure which shows the optical waveguide holding member and optical transceiver of this Embodiment, (a) is a perspective view which shows the whole, (b) is a perspective view which shows only a printed circuit board. It is a figure which shows the housing | casing of the optical waveguide holding member of this Embodiment, (a) is a perspective view which shows a front surface, a plane, and a right side surface, (b) is a perspective view which shows a bottom surface, a back surface, and a left side surface. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical transceiver 11 Printed circuit board 12 Optical waveguide holding member 12A Case 12B Connection part 12C Optical waveguide formation surface 12D Groove 12E Element side lens 12F Fiber side lens 13 Photoelectric conversion element 13A Light emitting / receiving part 14 Core member

Claims (4)

An optical waveguide holding member that is mounted on a printed circuit board of an optical transceiver that converts electrical signals and optical signals, and that holds an optical waveguide between an external optical fiber and a photoelectric conversion element mounted or formed on the printed circuit board. And
A first connection part for optically connecting the first end of the optical waveguide to the light receiving and emitting part of the photoelectric conversion element;
A second connection for optically connecting the second end of the optical waveguide to the external optical fiber;
A housing for holding the first connection portion and the second connection portion and holding an optical waveguide formed between the first connection portion and the second connection portion, and the first connection portion, The optical waveguide holding member, wherein the second connection portion and the casing are integrally formed of a clad material containing carbon nanotubes or carbon fullerenes.   2. The optical waveguide holding member according to claim 1, wherein the first connection portion and the second connection portion include lenses that are integrally formed with the first connection portion and the second connection portion.   The optical waveguide holding member according to claim 1 or 2, wherein a length of the carbon nanotube is equal to or less than a wavelength of the optical signal. A printed circuit board on which the photoelectric conversion element is mounted or formed;
An optical transceiver comprising the optical waveguide holding member according to any one of claims 1 to 3.

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