JP2000028863A - Parallel transmission type optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange optical elements of a high yield by a simple method in an optical module arranged with the optical elements arrayed in plural pieces and array-like optical fibers approximately coincident with the arranging spacings and optical axes of these optical elements and approximately uniform in pitches on a common packaging substrate. SOLUTION: The array-like optical elements 20 of multiple channels are composed of a plurality of single optical elements or a plurality of minor channels array-like optical elements. The spacings between the optical elements 20 are set integer times the array pitch of the optical fibers 21 and larger than the number of the channels by the optical elements 20. The array optical fibers 21 of the 16 channels inclusive of the excess channels (#1, #2, 4j3, #4) are exactly formed at the specified pitch and, therefore, the easy insertion of the fibers to the fixing grooves formed at the packaging substrate 22 is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a parallel transmission type optical module, and more particularly to a parallel transmission type optical module for optical communication.

[0002]

2. Description of the Related Art Optical fibers, laser diodes (LD), and light emitting diodes (LE)
D), photodiode (Photo Diode; P)
D) and the like, the application range of optical communication is expanding by increasing the performance and functionality of passive and active elements such as optical switches, optical modulators, isolators, and optical waveguides. In recent years, with increasing demands for transmitting more information, parallel transmission that performs data transmission between computer terminals, exchanges, and large computers in parallel in real time has been receiving attention. To satisfy this function, there is a parallel transmission type module in which a plurality of light emitting or light receiving elements and a plurality of optical fibers are integrated.

[0003] Normally, as a light-emitting (light-receiving) element for converting between an electric signal and an optical signal, an LD, LED or PD array monolithically arranged on the same semiconductor substrate is used. An optical fiber array in which a plurality of optical fibers are arranged in one direction is used as the optical fiber.

FIG. 6 is a perspective view showing a configuration of a general parallel transmission optical module. As shown in the figure, in a general optical module, an eight-channel arrayed optical element 20 is arranged on a silicon (Si) substrate 22. Then, an eight-channel array optical fiber 21 is arranged near the light emitting position (in the case of a light emitting element) or the light receiving position (in the case of a light receiving element) of the optical element 20.
The array optical fibers 21 are usually formed in a ribbon shape at 250 μm pitch. This optical fiber 2
Reference numeral 1 denotes a V-shaped groove 23 having a cross section formed by anisotropic etching.

[0005] Of the ten electrodes 11 arranged on the surface of the substrate 22 in FIG.
The electrode and the other eight electrodes are p-electrodes. At least one n-electrode is required, and two n-electrodes are provided in this example in consideration of the balance at the time of chip mounting.

Normally, light emitted from an optical element 20 such as an edge-emitting type LD is directly coupled to an optical fiber 21 facing it as shown in FIG. In general, in an optical element 20 such as a PD which is a surface light receiving type, light emitted from an optical fiber 21 is directed upward by a mirror surface 25 formed on a slope of a V-groove 23 as shown in FIG. After being reflected, the optical element 2
Bind to 0. 7 and 8 show the substrate 2 in FIG.
2 is a cross-sectional view of the V-shaped groove 23 cut in the length direction.

[0007]

By the way, in the optical parallel transmission type module, all channels need to operate normally. Therefore, all the elements included in the optical elements such as the array LD and the array PD are required to operate normally with uniform characteristics.

However, in practice, it is not easy to manufacture an array element having 8 to 12 channels. Even if the yield of a single element is 80%, the probability of a non-defective product for eight consecutive channels is reduced to 17%, and that for 12 channels is reduced to 7%. Therefore, it is difficult to manufacture a low-cost array optical element, which leads to an increase in module cost.
In particular, this tendency is remarkable because the yield of LD is not high.

For this reason, it is impractical to configure an optical parallel transmission type module using a multi-channel array optical element as a light emitting element or a light receiving element. In order to reduce the risk of increasing the number of channels, a method in which a plurality of elements having a small number of channels are used and arranged close to the same substrate can be considered.
For example, with respect to 12 channels, a method is considered in which three 4-channel arrays are arranged close to the same substrate.

However, it is difficult to cut out an optical element with an accuracy of a micrometer. Even if high-precision cutting is realized, it is difficult to mount the four-channel array elements adjacent to each other without a gap. Therefore, each array optical element is provided with a gap.

Therefore, the distance between the channels is constant within one array optical element, but the distance between the array optical elements is widened. Therefore, in mounting the 12-channel array optical fiber 21 having a fixed arrangement pitch, it is difficult to separate the array optical fiber into twelve single lines and mount them on the Si substrate 22 with a wide interval. There is a disadvantage that a process is required.

Further, depending on the arrangement pitch, as shown in FIG. 9, the optical fiber may be mounted in a curved manner. That is, as shown in the figure, when 12 channels are realized by three optical elements 20, if the arrangement pitch of the optical elements 20 does not match the arrangement pitch of the array optical fibers, the array optical fibers are replaced with a single core. The optical fiber must be divided into optical fibers, and the optical fibers of the channels ch5 to ch8 must be curved and mounted. There is a disadvantage that the mounting operation for bending the optical fiber is difficult. Also in Japanese Patent Application Laid-Open No. 2-93415, the optical fiber is curved, and mounting work is difficult.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a parallel transmission type optical module which can be easily mounted and assembled.

[0014]

A parallel transmission type optical module according to the present invention has N (N is a positive integer) elements arranged on a substrate surface and each of the arranged elements converts between an electric signal and an optical signal. The optical element group and the array intervals arranged on the substrate surface are substantially uniform, and the array interval substantially matches the array interval of the optical element group, and corresponds one-to-one with each element of the optical element group. A parallel transmission type optical module including M (M is a positive integer) optical fiber arrays composed of optical fibers optically coupled with the optical axes of the elements substantially coincident with each other; The arrangement interval is an integral multiple of the arrangement interval of the optical fibers, and the number M of the optical fiber arrays is larger than the number N of the optical element groups.

Another parallel transmission type optical module according to the present invention is a group of N (N is a positive integer) optical elements which are arranged on the substrate surface and each of the arranged elements converts between an electric signal and an optical signal. And the arrangement pitch is substantially uniform, and the arrangement interval is substantially equal to the arrangement interval of the optical element group, and from the optical fiber optically coupled to the corresponding element corresponding to each element of the optical element group on a one-to-one basis. A parallel transmission type optical module including M (M is a positive integer) optical fiber arrays, wherein the optical element groups are arranged in a plurality of rows at predetermined intervals.

In short, in the present optical module, the gap between the array optical elements is set so that the pitch between the adjacent adjacent channels is an integral multiple of the array pitch of the optical fibers, and the array optical fibers are connected to the array optical elements. In addition to the channel, an extra optical fiber channel corresponding to the gap is provided. Usually, the pitch of the array optical fiber is 250
μm, the pitch of adjacent channels between the array elements is 0.5 mm, 0.75 mm, 1.0 mm,
The cutting error of the array optical element of several tens μm can be neglected. In the case of 0.75 mm, two channels extra optical fiber is required. Therefore, when 12 channels are constituted by 3 elements of a 4-channel array, 1 + 2 + 2 + 2
What is necessary is just to prepare an array optical fiber of 6 channels.

Also, array optical elements of a small number of channels are arranged alternately (in a so-called staggered pattern) in a plurality of rows, for example, two rows, with the spacing between the rows being equal to or longer than the element length. That is, the array optical elements are arranged so that the ends are alternately positioned at the two dicing grooves. By arranging in this way, a parallel transmission type optical module that is easy to assemble at low cost can be realized. Since the distance between adjacent optical elements is large, the optical elements can be independently mounted without requiring the precision of cutting out the elements, and the optical fibers can be configured with the same number of channels as the number of arrays of the optical elements. Further, by disposing the tip of the array optical fiber so as to be close to the corresponding optical element, a module having uniform characteristics between the arrays can be realized. If the mounting substrate is silicon, a groove for fixing the array optical fiber and a mirror for optical coupling between the PD and the optical fiber can be easily formed. When mounting an LD, a V-groove can be easily formed by anisotropic etching, and the terminal end of the V-groove on the optical element side is vertically processed by dicing to easily align the optical fiber in the optical axis direction. It can be carried out.

When the LDs are arranged in a plurality of rows, a plurality of dicing grooves are formed. In this case, the electrodes of the LDs in the front row are separated due to the dicing grooves in the rear row. For connection of the divided electrodes, a wiring element arranged like a bridge so as to straddle a groove is used. If a plurality of optical elements including this wiring element are joined by solder bumps, all the elements can be joined at once with high accuracy, and the mounting cost can be reduced.

[0019]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same reference numerals are given to the same parts as those in the other drawings.

FIG. 1 is a top view showing an embodiment of a parallel transmission type optical module according to the present invention. In FIG. 1, three optical elements 20, such as a four-channel array LD, are mounted on a mounting substrate 22, for example, a Si substrate, for a total of 12 channels of L.
D is arranged together with the split electrode 11, and an array optical fiber 21 is arranged close to the light emitting surface. The array pitch of the array optical fibers 21 is 250 μm, and the array pitch of the four-channel LD is also set to the same 250 μm. Since the spacing between adjacent channels (ch4 and ch5, ch8 and ch9) between the arrayed optical elements 20 is set to 750 μm, which is equivalent to two channels, all LDs are arranged at a pitch of 250 μm. It is arranged at a position exactly facing the optical fiber. The element spacing is about 500 μm, and can be mounted without contacting adjacent elements. In addition, it is possible to eliminate a mounting defect due to a width direction cutout error of an element of about several tens μm.

The array optical fiber 21 is composed of 16 channels, including extra channels (# 1, # 2, # 3, # 4) at intervals between array LD elements. Since the 16-channel array optical fibers 21 are accurately formed at a pitch of 250 μm, they can be easily inserted into the fixing grooves formed in the mounting substrate. The mounting cost can be greatly reduced as compared with the conventional mounting method in which the array optical fiber has to be divided into a single core and mounted in a curved state.

That is, the present optical module comprises an optical element in which a large number of channels are formed by a plurality of array optical elements of a small number of channels, and an array optical fiber having a normal uniform pitch. If an optical fiber mounting method is adopted, it can be easily assembled.

As described above, the present optical module includes N (N is a positive integer) optical element groups arranged on the substrate surface and each of the arranged elements converts between an electric signal and an optical signal. It is being done. Also, the present optical module is arranged on the substrate surface, the arrangement interval is substantially uniform, the arrangement interval substantially matches the arrangement interval of the optical element group, and one-to-one corresponds to each element of the optical element group. M optical fibers (M is a positive integer) composed of optical fibers optically coupled with their optical axes substantially coincident with each other
Of the optical fiber array.
The arrangement interval of the optical element groups is an integral multiple of the arrangement interval of the optical fibers, and the number M of the optical fiber arrays is larger than the number N of the optical element groups.

Next, another embodiment of the parallel transmission type optical module of the present invention will be described with reference to FIGS. FIG. 2 is a top view of the optical module, and FIG.
It is sectional drawing of a part.

Referring to FIG. 2, an optical element 20 as a four-channel array LD is mounted on a mounting substrate 22, for example, a Si substrate.
And optical elements of a total of 12 channels are alternately arranged in two rows at a pitch of 250 μm. Here, the column interval between the two rows of array-shaped optical elements 20 is set to be longer than the element length of the optical elements 20, that is, the length in the optical axis direction. Therefore, regardless of the cutting error in the width direction of the array LD, c
The interval between h4 and ch5, and the interval between ch9 and ch10
It can be set to 250 μm, the same as h. Further, since the distance between adjacent arrays LD is sufficiently large, each array LD can be mounted independently.

The array optical fiber 21 is composed of eight cores having a pitch of 250 μm corresponding to the optical element 20, and is mounted in a fixed groove formed on a mounting substrate without being bent. The tip of the array optical fiber 21 on the optical element 20 side is
It is arranged near the corresponding optical element 20. That is, by arranging the ends of the optical fibers in two rows following the optical element 20, a stable module with small variation in characteristics between channels is realized.

If the mounting substrate 22 is made of Si,
It is possible to improve the mounting accuracy and simplify the assembly. That is, if anisotropic wet etching is performed on the Si mounting substrate 22 with a strong alkaline etchant, a highly accurate V-groove can be formed, and the array optical fiber 21 can be mounted with high accuracy.

By the way, referring to FIG.
The end on the side is located near the dicing groove 12 or 13. That is, the end of the V-groove is formed into a vertical cross-sectional shape by dicing. In this case, FIG.
As shown in (a), the dicing saw 40 rotating as shown by the arrow Y41 is moved to the V-groove 23 as shown by the arrow Y42.
And contact it with the end. By doing so, as shown in FIG. 4B, dicing grooves 13 perpendicular to the substrate surface are formed at the ends of the V grooves 23.
An optical fiber 21 is inserted into the vertical dicing groove 12 or 13.
By pressing the tip, the positioning in the optical axis direction can be easily performed.

When the optical element 20 is an edge-emitting type LD or the like, it is directly optically coupled to the opposing optical fiber 21 as shown in FIG. Then, the end of the V-groove is formed into a vertical cross-sectional shape by dicing. On the other hand, when the optical element 20 is a surface-receiving type PD or the like, the light is reflected by the mirror surface formed on the slope of the V-groove as shown in FIG. No processing is applied.

When the dicing process is performed, a part of the electrode is broken by the rear dicing groove 13. In this case, as shown in FIG. 3, by arranging the wiring element 14 so as to straddle the groove 13, the electrodes can be easily connected.

As shown in FIG. 5A, the wiring element 14 electrically connects the electrodes 11 cut by forming the dicing grooves 13 by the wiring element 14. As shown in FIG. 2B, the wiring element 14 is provided with a number of electrodes 51 corresponding to the number of the electrodes 11. In this example, the electrode 11 and the electrode 5
1 is four. Then, as shown in FIG. 3C, the electrode 51 is electrically connected to the electrode 11 by the solder bump 15. The electrode 51
May be the same or different.

The broken portion of the electrode 11 can be connected by well-known wire bonding. However, if the wiring element 14 and the array LD as the optical element 20 are joined by the solder bumps 15 as in this example, all the elements can be joined at once, and the mounting cost can be reduced.

In this example, the case of an array element having 12 channels has been described, but it is apparent that similar effects can be obtained with other channels. In this example, the case where the array pitch is 250 μm has been described, but another pitch value may be used. Further, in this example, the case where the number of arrays is two is described, but the number of arrays may be three or more.

That is, the present optical module comprises an optical element having a large number of channels formed by a plurality of array optical elements having a small number of channels, and an array optical fiber having a normal uniform pitch. If an optical fiber mounting method is adopted, it can be easily assembled.

As described above, the present optical module is configured to include N (N is a positive integer) optical element groups arranged on the substrate surface and each of the arranged elements converts between an electric signal and an optical signal. It is being done. Further, in the present optical module, the arrangement pitch is substantially uniform, the arrangement interval is substantially equal to the arrangement interval of the optical element group, and the optical element is one-to-one corresponding to each element of the optical element group and optically coupled to the corresponding element. M fibers (M
Is a positive integer). The optical element groups are arranged in a plurality of rows at a predetermined interval from each other.

The present invention can take the following aspects in connection with the description of the claims.

(1) The optical module according to any one of claims 1 to 11, wherein the optical element group is connected to the substrate by solder bumps.

12. The parallel transmission type optical module according to claim 10, wherein said wiring element is connected to said substrate by solder bumps.

[0039]

As described above, according to the present invention, the arrangement interval of the optical element groups is set to be an integral multiple of the arrangement interval of the optical fibers and the number of the optical fiber arrays is set to be larger than the number of the optical element groups.
By arranging the optical element groups in a plurality of rows at a predetermined interval from each other, there is an effect that a parallel transmission type optical module which is easy to mount and assemble can be realized.

[Brief description of the drawings]

FIG. 1 is a top view showing a configuration of a parallel transmission type optical module according to an embodiment of the present invention.

FIG. 2 is a top view showing a configuration of a parallel transmission type optical module according to another embodiment of the present invention.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4A is a diagram illustrating a state in which the end portion of a V-groove is diced, and FIG. 4B is a diagram illustrating a formed dicing groove.

FIG. 5A is a diagram showing a mounting state of a wiring element, and FIG.
Is a bottom view of the wiring element, and (c) is a side view of the wiring element.

FIG. 6 is a perspective view showing a configuration of a conventional parallel transmission type optical module.

FIG. 7 is a diagram showing an optical coupling state of light emitted from an edge-emitting type optical element to an optical fiber.

FIG. 8 is a diagram showing an optical coupling state of light emitted from a surface light receiving type optical element to an optical fiber.

FIG. 9 is a diagram showing a state where an optical fiber is mounted in a curved state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wiring element 11 Electrode 12, 13 Dicing groove 20 Optical element 21 Array optical fiber 22 Substrate 23 V groove

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/13 10/12

Claims (11)

[Claims] An array of N (N is a positive integer) optical elements, each of which is arranged on a substrate surface and each of the arranged elements converts between an electric signal and an optical signal, is arranged on the substrate surface and has an arrangement interval. This arrangement is substantially uniform, and the arrangement interval substantially coincides with the arrangement interval of the optical element group, and the optical axis and the optical axis of the corresponding element correspond to each element of the optical element group in a one-to-one correspondence, and optical coupling is performed. A parallel transmission type optical module including M (M is a positive integer) optical fiber arrays composed of separated optical fibers, wherein the arrangement interval of the optical element groups is an integral multiple of the arrangement interval of the optical fibers. , The number M of the optical fiber arrays is equal to the number N of the optical element groups.
A parallel transmission type optical module characterized by being larger than the above. 2. A group of N optical elements (N is a positive integer), each of which is arranged on the surface of a substrate and converts each of the arranged elements into an electrical signal and an optical signal, and an array having a substantially uniform array pitch M (M is a positive integer) consisting of optical fibers whose intervals substantially coincide with the arrangement intervals of the optical element group, and which correspond one-to-one with each element of the optical element group and are optically coupled to the corresponding elements. A parallel transmission type optical module comprising: an optical fiber array according to any one of claims 1 to 3, wherein the optical element groups are arranged in a plurality of rows at predetermined intervals. 3. The parallel transmission type optical module according to claim 2, wherein the optical element groups are arranged alternately with respect to the plurality of columns. 4. The parallel transmission type optical module according to claim 2, wherein the predetermined interval is longer than a length of the optical element group in an optical axis direction. 5. The substrate according to claim 1, wherein each of the optical fibers is provided on the surface of the substrate so as to correspond to each of the optical fibers, and a cross section of the optical fibers is fixed to a V-shaped groove. Item 5. The parallel transmission type optical module according to any one of Items 1 to 4. 6. The parallel transmission type optical module according to claim 5, wherein the groove is formed by anisotropic etching. 7. The optical element is characterized in that each element of the optical element group and an end of an optical fiber corresponding to each element are located close to each other, whereby each element and the corresponding optical fiber are optically connected. The parallel transmission type optical module according to claim 1. 8. An end of the groove portion is processed perpendicular to a surface of the substrate.
The parallel transmission type optical module according to any one of the above. 9. The parallel transmission type optical module according to claim 8, wherein an end of the groove is vertically processed by dicing. 10. A wiring pattern provided corresponding to each of the grooves and electrically connected to each element of the optical element group, and portions of these wiring patterns cut by dicing grooves formed by the dicing. The parallel transmission type optical module according to claim 9, further comprising: a wiring element for electrically connecting the optical module. 11. The parallel transmission type optical module according to claim 10, wherein the wiring element is provided across the dicing groove so as to electrically connect the disconnected portion.