JP2007317940A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize a crosstalk quantity of each of channels in an optical module where the plurality of channels are provided each consisting of an optical element, an integrated circuit and a wiring for connecting the integrated circuit with the optical element. <P>SOLUTION: The optical module 10 is formed in such a way that the four or more channels each consisting of the optical element 14, the integrated circuit 16 and the wiring 18 for connecting the integrated circuit 16 to the optical element 14 are formed on a substrate 12. In the module 10, the four or more sets of wiring 18 are juxtaposed and arranged in a direction crossing the extending directions of them, and an interval between the sets of wiring 18 is set to be smaller in an end position of the arrangement direction than in a position other than the end position. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical module, and more particularly to an optical module that processes or outputs a plurality of optical signals in parallel.

  Conventionally, for example, as shown in Patent Documents 1 and 2, a plurality of optical signals are transmitted using optical waveguides such as separate optical fibers, and the optical signals emitted from the respective optical waveguides are received by the respective light receiving elements in parallel. It is considered to process automatically. In such a case, a separate integrated circuit is connected to each of the plurality of light receiving elements via wiring, and electrical signals output from the respective light receiving elements are processed in parallel by these integrated circuits. In this case, each light receiving element, an integrated circuit provided corresponding to each light receiving element, and a wiring connecting the integrated circuit and the light receiving element are formed on a common substrate and used as one optical module. Is common.

  Usually, a plurality of light receiving elements constituting the above-described optical module are arranged in a line and used in the form of a light receiving element array. In this case, wirings connected to the respective light receiving elements are arranged on the substrate. Will be established. That is, the plurality of wirings are arranged side by side in a direction intersecting with the direction in which the plurality of wirings extend (generally, a direction orthogonal to each other). In such a conventional configuration, the channels made up of the light receiving elements, wirings, and integrated circuits are arranged at equal intervals, but are aligned when the intervals are set small in order to reduce the size of the optical module. Signal crosstalk is likely to occur between a plurality of light receiving elements, between wirings, between wirings connecting wirings and light receiving elements, and the like.

Conventionally, various measures for reducing such crosstalk have been proposed. For example, in the above-mentioned Patent Document 2, a light receiving element provided with a means for inputting an output signal to a signal detection circuit and a common electrode are used. A configuration in which connected light receiving elements are alternately arranged is shown.
JP 2002-198908 A JP 2001-257335 A

  By the way, in an optical module in which a plurality of channels including light receiving elements, integrated circuits, and wirings connecting them are arranged at equal intervals as described above, the crosstalk amount is generally a channel close to the center position in the channel arrangement direction. And becomes smaller in the end position channel. In other words, there is only one adjacent channel of the end channel inside, whereas there are two adjacent channels in the channel other than the end channel, and further between the channels outside the adjacent channel. However, since crosstalk sometimes occurs, this is the tendency.

  The conventional technology for reducing the crosstalk has a certain effect, but the same countermeasure is taken for each of the plurality of channels, so that the difference in the amount of crosstalk between the plurality of channels should be dealt with. I can't. If this is the case, the crosstalk may be sufficiently reduced in the channel at the end portion, but a problem may occur in which a large amount of crosstalk remains in the channels at other positions.

  The optical module that receives and processes the signal light has been described above as an example. The light emitting element such as a semiconductor laser, the integrated circuit for driving the light emitting element, and the wiring that connects the integrated circuit and the light emitting element. The same crosstalk problem may occur even in an optical module in which optical channels are formed on a plurality of substrates and output optical signals from a plurality of light emitting elements in parallel.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to equalize the crosstalk amount for each channel in an optical module having a plurality of channels for processing or outputting optical signals.

The first optical module according to the present invention comprises:
In an optical module in which four or more channels formed of a light receiving element or an optical element composed of a light emitting element, an integrated circuit, and wiring connecting the integrated circuit and the optical element are formed on a substrate
Four or more of the wirings are arranged side by side in a direction intersecting with the extending direction thereof,
The distance between the wirings is set to be larger in the central position in the arrangement direction than in the other positions.

  Note that the spacing between wirings is odd when the wiring is even, and is even when the wiring is odd. Therefore, the interval at the central position in the wiring arrangement direction indicates one interval in the middle when the number of intervals is odd, and the interval of the wiring existing in the center when the number of intervals is even. Two spacings on both sides shall be indicated.

  In the first optical module according to the present invention, it is particularly desirable that the distance between the wirings is set so as to gradually decrease from the center position in the arrangement direction to the end position.

  Note that the interval between the wirings varies depending on the position in the length direction of the wiring when the two wirings are not formed in parallel to each other. The “interval between wirings” in the present invention includes an average interval in such a case.

The second optical module according to the present invention is:
In the optical module in which three or more channels formed of optical elements, integrated circuits, and wirings connecting the integrated circuits and the optical elements are formed on the substrate in the same manner as described above.
The three or more wirings are arranged radially at substantially equal angular intervals.

  As is well known, when a plurality of channels including the above-described optical elements, integrated circuits, and wirings are provided, the crosstalk tends to increase as the wiring interval is shorter. In the first optical module according to the present invention, the interval between the four or more wirings is set to be larger at the center position in the arrangement direction than at the other positions. In the configuration in which the channels are arranged at equal intervals, the above-mentioned tendency that the crosstalk amount increases in the channel at the center position can be compensated, and the crosstalk amount of each channel can be made uniform. If so, even if the same crosstalk reduction measure is applied to each channel, the crosstalk of each channel can be reduced to substantially the same level.

  In the first optical module, particularly when the interval between the wirings is set so as to gradually decrease from the center position in the arrangement direction to the end position, the above tendency of crosstalk is further increased. It is possible to compensate accurately and make the crosstalk amount more uniform.

  The difference between crosstalk amounts becomes a problem when there are two or more adjacent channel pairs (intervals between wirings), that is, when there are three or more channels. If there are two pairs, that is, the number of channels is 3, there are two wiring intervals at the end position in the wiring arrangement direction, but there is no wiring interval at the central position in the wiring arrangement direction to be compared with that. Become. In other words, in this case, the wiring interval at the end position in the wiring arrangement direction and the wiring interval at the center position in the wiring arrangement direction are common. Therefore, in order for the first optical module according to the present invention to equalize the crosstalk amount according to the technical idea, it is premised that there are three or more adjacent channel pairs. The requirement is that the number of channels is 4 or more.

  On the other hand, in the second optical module according to the present invention, since three or more wires are arranged radially at substantially equal angular intervals, the wires are different from the case where the wires are arranged in one direction. Since the end position and the center position in the arrangement direction do not exist and the crosstalk generation condition is common to each channel, the crosstalk amount of each channel is made uniform.

  As described above, in the conventional technique in which the channels are arranged in parallel, the difference in crosstalk amount becomes a problem when there are two or more pairs of adjacent channels, that is, the number of channels is 3. This is the case. Therefore, in order for the second optical module according to the present invention to exhibit the effect of making the crosstalk amount uniform with respect to the above-described conventional technology, it is premised that the number of channels is three or more. This is a requirement for optical modules.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 are a perspective view and a side view, respectively, showing an optical module according to a first embodiment of the present invention. As illustrated, the optical module 10 includes a substrate 12, eight light receiving elements 14 arranged in a line on the substrate 12, an eight integrated circuits 16 also formed on the substrate 12, Each of the light receiving elements 14 and the integrated circuit 16 includes a linear wiring 18 and a wiring 20 that connect the integrated circuit 16, and a lead 22 that connects the integrated circuit 16 to an external circuit. Of the elements described above, a part of the lead 22 and all other elements are enclosed in the transparent resin package 24.

  In the above configuration, each set (channel) including one light receiving element 14, the integrated circuit 16, the wiring 18, and the wiring 20 transmits and processes a signal independently of the other sets. That is, for example, signal light 30 that is appropriately collected after being emitted from an optical waveguide such as an optical fiber enters each light receiving element 14, and the light receiving element 14 converts the received signal light 30 into an electrical signal. The electrical signal is input to the integrated circuit 16 via the wiring 18 and the wiring 20. Then, the integrated circuit 16 performs a predetermined process on the electrical signal, and the processed signal is transmitted to the outside of the optical module via the lead 22.

  The eight wirings 18 are made of, for example, printed wirings, and are arranged in a direction orthogonal to the direction in which the eight wirings 18 extend, and are appropriately spaced from each other. In the present embodiment, since the number of the channels is 8, there are seven intervals between the wirings 18, but as shown in the figure, these intervals are maximum at the center position in the arrangement direction of the wirings 18, and are arranged from there. It is set to a state where it gradually decreases as it goes to both ends of the direction, and is minimized at both ends.

  Here, in the above-described configuration, crosstalk may occur between the channels (more specifically, between the eight wirings 18). If the interval between the eight wirings 18 is constant, as described above, the amount of crosstalk generally increases in the channel near the center position in the channel arrangement direction, and in the channel at the end position. There is a tendency to become smaller.

  On the other hand, in the optical module 10 of the present embodiment, the distance between the eight wirings 18 is set to be larger at the center position in the arrangement direction than at the other positions. By compensating for the above tendency, the crosstalk amount of each channel can be made uniform. If so, even if the same crosstalk reduction measure is applied to each channel, the crosstalk of each channel can be reduced to substantially the same level.

  In particular, in the present embodiment, the interval between the wirings 18 is particularly the end portion from the center position in the arrangement direction (here, the position where the amount of crosstalk is maximized when the channels are arranged at equal intervals). Since it is set so as to gradually become smaller as it goes to the position, it is possible to more accurately compensate for the above-mentioned tendency of crosstalk and make the crosstalk amount more uniform.

  In the optical module 10 according to the first embodiment described above, the signal light 30 is incident on the substrate 12 perpendicularly. However, the signal light 30 can be incident on the substrate 12 in parallel. It is. 3 and 4 are a plan view and a side view showing the optical module 40 according to the second embodiment of the present invention configured as described above. 3 and 4, the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted unless necessary (the same applies hereinafter).

  As shown in FIGS. 3 and 4, in the second embodiment, the leads 42 and 44 formed so as to protrude from both ends of the substrate 12 are bent downward from the middle, and the optical module 40 is interposed therebetween. It can be attached to a mount (not shown) or a larger substrate. A cover member 46 made of a transparent material is formed on the upper surface in the vicinity of one end portion (left end portion in the figure) of the substrate 12, and the eight light receiving elements 14 are enclosed in the cover member 46. The cover member 46 is formed with a mirror surface 46 a that forms an angle of 45 ° with the surface of the substrate 12. The mirror surface 46a is a reflective surface, for example, by depositing metal on the surface of the cover member 46.

  In the above configuration, the signal light 30 is guided so as to enter the cover member 46 in a direction parallel to the substrate 12. Therefore, the signal light 30 is reflected by the mirror surface 46a, changes the optical path downward, and enters the light receiving element 14 from above. Also in the second embodiment, the interval between the eight wirings 18 is the same as that in the first embodiment, so that in this embodiment as well, the cross of each channel is the same as in the first embodiment. The effect of making the talk amount uniform can be obtained.

  Next, FIG. 5 shows an optical module 50 according to a third embodiment of the present invention. In the third embodiment, the wirings 18 are arranged radially on the circular substrate 52 at equal angular intervals, and the light receiving element 14 and the integrated circuit 16 are arranged inside and outside, respectively. In this optical module 50, unlike the case where the wirings are arranged in one direction, the end position and the center position in the arranging direction of the wirings 18 do not exist, and the crosstalk generation condition is common to each channel. Therefore, the crosstalk amount of each channel is made uniform.

  In the above, three embodiments having eight channels have been described, but the number of channels is not limited to eight in the optical module of the present invention. That is, as described above, the present invention can be applied to any number of channels as long as it is 4 or more in the configuration as shown in FIG. 1 or 3 and 3 or more in the configuration as shown in FIG. It is applicable and has the effect as described above.

  Further, the embodiment of the optical module configured to include a plurality of light receiving elements 14 and process a plurality of optical signals in parallel has been described above. However, as described above, a light emitting element such as a semiconductor laser, and the like. The present invention can also be applied to an optical module in which a channel including an integrated circuit for driving a semiconductor device and a wiring connecting the integrated circuit and a light emitting element is formed on a plurality of substrates. The effect by the above-mentioned this invention is acquired similarly.

The perspective view which shows the optical module by the 1st Embodiment of this invention Side view of the optical module of FIG. The top view which shows the optical module by the 2nd Embodiment of this invention Side view of the optical module of FIG. The front view which shows the optical module by the 3rd Embodiment of this invention

Explanation of symbols

10, 40, 50 Optical module 12, 52 Substrate 14 Light receiving element 16 Integrated circuit 18 Wiring 20 Wiring 30 Signal light

Claims (4)

In an optical module in which four or more channels including optical elements, integrated circuits, and wirings connecting the integrated circuits and the optical elements are formed on a substrate,
Four or more of the wirings are arranged side by side in a direction intersecting with the extending direction thereof,
The optical module is characterized in that the interval between the wirings is set to be larger at the central position in the arrangement direction than at other positions.   The optical module according to claim 1, wherein an interval between the wirings is set so as to gradually decrease from a center position in an arrangement direction to an end position. In an optical module in which three or more channels comprising optical elements, integrated circuits, and wirings connecting the integrated circuits and the optical elements are formed on a substrate,
An optical module, wherein three or more wirings are arranged radially at substantially equal angular intervals.   4. The optical module according to claim 1, wherein the optical element is a light receiving element and / or a light emitting element.

Images