JPH11258455A - Optical waveguide component and optical waveguide module using the component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide module to which optical fibers can be accurately and simply connected using highly accurate and inexpensive optical waveguide components. SOLUTION: An optical waveguide formed on a flat substrate of an optical waveguide component and a fiber connecting member having a drilled fiber inserting hole are provided at the end part of the optical waveguide, and the optical axes of the optical waveguide and of an optical fiber passing through a fiber inserting hole are regulated by fitting a fitting recessed part 12 provided at a fixed position of the optical waveguide on a fitting projection 22 provided at a fixed position of the fiber connecting member to fit in the recessed part 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the construction and manufacture of a planar optical waveguide module used in fields such as optical communication and optical information processing. More specifically, the present invention relates to an optical waveguide module with an optical connector that can be easily and detachably attached via an optical connector portion while maintaining the optical fiber connection to the planar optical waveguide with high accuracy.

[0002]

2. Description of the Related Art Planar Lightwave Cuirc
In the era of information communication using optical fibers, uits (PLC circuits) can be used for multiplexing / demultiplexing and branching of light in a small area, and thus their applications are expected. In recent years, an optical communication system incorporating a planar optical waveguide circuit (PLC) has been developed and actually used. In an optical line test system, AUROL automatically demultiplexes test light and communication light, and automatically tests the optical line without interrupting signal light.
The A system is one example. (N.Tomita et al. "Ad
vanced optical fiberline testing system "NOC'pp.9
6, 30-37, 1966). Further, in the planar optical waveguide circuit, an AWG (array waveguide diffraction grating) has been actively used as a wavelength division multiplexing multi-demultiplexer in a wavelength multiplexing optical transmission / reception module or the like.

The most problematic in such a use form is the connection between an optical fiber and a PLC circuit. Since the PLC circuit has an optical waveguide integrated on a flat substrate made of quartz or silicon, the light input / output end is basically the end surface of the flat substrate and does not essentially match the cylindrical end surface of the optical fiber.
Various configurations have been studied and reported to avoid these problems and to make the connection with the optical fiber smooth and easy. Currently, practically used are optical fiber blocks in which optical fiber groups to be connected are arranged one-dimensionally or two-dimensionally so as to be aligned with the plane of the end face of the PLC, and are bonded with a UV adhesive or the like. This is a method of fixing to the PLC end face. This means that as the number of connected optical fibers increases, the optical fiber arrangement accuracy of the fiber block is required to be stricter, but it has been reported that up to 32 fibers can be connected well in the current technical range. .

[0004] Another method is to provide an optical connector on the PLC substrate side for connection to an optical fiber. This is a very advantageous method for mounting the optical circuit module in that the connection between the optical fiber and the PLC circuit is detachable. However, in the examples so far, the shape and size of the optical connector and the positional accuracy are technical constraints, and it has not been possible to realize a highly efficient configuration.

FIGS. 6 and 7 show examples of connection between a PLC substrate and an optical fiber. FIG. 6 shows an example of a permanent connection between a PLC circuit and a fiber block. In FIG. 6, reference numeral 01 denotes a reinforcing plate, 02 denotes a waveguide end face, 03 denotes a waveguide substrate, 04 denotes a fiber block reinforcing plate, and 05 denotes an optical fiber block. The optical fiber array part of 06, the fiber block board, 07
Shows a multi-core optical fiber tape. Waveguide end face 0
2 and the fiber block 06 are fixedly connected when the light coupling is maximized by fine movement in the XYZ directions. This is called alignment connection or active alignment. Such a connection form has a low connection loss and excellent connection reliability, but is disadvantageous in that cost and work time are required for precision fabrication of the fiber block 06, alignment work, and the like. In addition, when a post-process operation such as mounting a board after manufacturing a module is performed, it is difficult to handle the extra length of the mounted optical fiber.

FIG. 7 shows a P-type circuit proposed to improve the disadvantage of the permanent connection of the optical fibers of the PLC circuit shown in FIG.
This is an example of a configuration of an LC circuit module with an optical connector (see Japanese Patent Application Laid-Open No. 1-223307). 7, reference numeral 011 denotes a pin fixing adhesive hole, 012 denotes a connector structure, 012 denotes an optical waveguide circuit, 014 denotes a connection pin, 015 denotes a pin receiving hole, 016 denotes an optical fiber connection block, and 017.
Shows optical fiber tapes respectively. In the example shown in FIG. 7, the position of the end face of the waveguide circuit 013 and the end face of the optical fiber connection block 016 are adjusted by the connection pin 014 attached to the PLC circuit module. After the PLC circuit module with connection pins is manufactured, the connection optical fiber connection block 016 is removed and the post-process can be performed, so that the handling of the module is very excellent. However, in the connection as shown in FIG. 7, since the fiber core portion and the waveguide core portion are aligned only with the connection pin 014, the sub-μm
There is a drawback that level matching accuracy is required, and it is very difficult to align and fix the pins in the holes at the time of manufacturing the PLC circuit module, thereby lowering the yield.

[0007]

SUMMARY OF THE INVENTION A planar optical waveguide (PL)
C) In the optical transmitting and receiving module, the problematic factors are roughly classified into two points. One is a connection between a planar waveguide and an optical fiber for external input / output. In general, many of the functions of an optical waveguide depend on the optical mode in the waveguide,
The waveguide mode is basically a single mode (SM), and the optical SM fiber to be externally connected is also a minute point connection having a core diameter of about 10 microns. Therefore, the alignment accuracy between the optical input / output end face of the waveguide and the connection fiber greatly affects the connection loss,
Desirably, an accuracy of 1 micron or less is desired. In order to ensure this accuracy, at present, modules are individually connected by centering or active alignment using a high-precision alignment device.

Another problem is extra length processing of the connected optical fiber. When the optical waveguide module has an independent function independently, for example, in the case of a coupler or splitter of an optical multiplexing / demultiplexing circuit, the manufactured optical module is packaged as one functional component. Handling tapes is not a problem. However, in a hybrid optical waveguide module in which an electric optical element, a light-emitting laser diode, a light-receiving photodiode, and the like are mounted on a PLC substrate, a process of mounting the manufactured module on a larger-scale board is usually performed. is there. In addition, it is necessary to mix and mount other semiconductor elements such as general electric printed circuit boards, LSIs, IC resistors, capacitors and the like, and the handling of the module becomes important. That is, in the optical waveguide hybrid module, it is desired that the optical fiber for performing the optical input / output with the outside is not a fixed connection but can be easily connected at the final shipping stage or in a user use environment to be connected.

Conventionally, a number of studies have been made on this point. However, most of the connectors which maintain the above-mentioned connection position accuracy and which can be connected to an optical fiber by a connector can be removed. There was none.

FIG. 8 shows an end face of a conventional optical waveguide connector with a pin guide. In FIG. 8, reference numeral 021 denotes a pin holding cap, 022 denotes a pin guide V groove, 023 denotes a guide pin, 024 denotes an optical waveguide, 025 denotes a distance between pins, and 026.
Denotes a V-groove depth, and 027 denotes an optical waveguide substrate. If the optical waveguide substrate 027 is made of silicon, the pin guide V-groove 022 shown in FIG. 8 is usually formed by anisotropic etching of a Si crystal by removing the photoresist from the width of the pin guide V-groove 022 in a photolithography process. . In this case, the tip angle α of the V groove is 71.4 degrees, and the guide pin 023
Is 750 μm, the V groove depth 026 is about 52
It becomes 7.6 μm, which is considerably deeper in the etching process of the Si substrate, and it is difficult to accurately maintain the sub-μm.

FIG. 9 is an enlarged image view of a groove side surface and a linear portion of the Si substrate after anisotropic etching. As shown in FIG. 9, V in the in-plane direction of the waveguide substrate (Si substrate) 031
The linearity of the groove 032 is also large in the above-described processing of 30 to 40 mm, so that the V groove etching surface 0
No. 33 had a step-like shape, and it was difficult to maintain the accuracy and linearity of μm or less similarly to the depth plane.

Further, an example in which the V-groove for pin guide is formed by machining with a dicing saw or the like has been studied. In this case, the normal V-groove is ground at a bevel angle of 60 degrees, and when the guide pin diameter is 750 μm, the groove depth is also 649.5 μm.
This also affects the mechanical strength of the waveguide substrate. Also, it has been very difficult to maintain the accuracy in the depth direction of the groove due to uneven thickness and warpage of the substrate.

FIG. 10 is a model diagram showing the influence of the thickness unevenness and the warpage of the substrate. In FIG. 10, reference numeral 041 denotes a processing plane optical waveguide substrate, reference numeral 042 denotes a processing reference line, reference numeral 043 denotes a dicing saw rotary blade, reference numeral 044 denotes a dicing movement line, and reference numeral 04 denotes a dicing movement line.
Reference numeral 5 indicates the amount of substrate warpage due to the formation of the planar optical waveguide. Actually, the substrate 041 is vacuum-adsorbed to the wafer holder to perform the plane correction, but it can be seen that it is extremely difficult to form a groove over a long distance due to a deviation of the parallel plane during polishing of the Si wafer.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an optical connector with an optical connector comprising an optical waveguide disposed on an optical waveguide formed on a flat substrate so that input and output lights are coupled via a detachable connector. An optical waveguide module in which connection with an optical fiber can be performed accurately and easily in an optical waveguide module. An object of the present invention is to provide a highly accurate and inexpensive optical waveguide component.

[0015]

According to a first aspect of the present invention, there is provided an optical waveguide formed on a planar substrate and a fiber connecting member having a fiber insertion hole formed therein. An optical waveguide component provided at an end of the waveguide, wherein a fitting recess provided at a predetermined position of the optical waveguide, and a fitting projection provided at a predetermined position of a fiber connection member fitted into the fitting recess. The optical axes of the optical waveguide and the optical fiber passing through the fiber insertion hole are adjusted by fitting.

According to a second aspect of the present invention, in the first aspect, the fitting concave portion of the optical waveguide has the substrate surface and the side surface of the optical waveguide which face the end surface of the optical waveguide and appear after the optical waveguide is removed. It is characterized by having.

According to a third aspect of the present invention, in the first or second aspect, the fitting protrusion of the fiber connection member is formed integrally with the fiber connection member.

According to a fourth aspect of the present invention, in the first to third aspects, the fiber connecting member is a resin molded product.

According to a fifth aspect of the present invention, there is provided an optical waveguide module in which a fiber is connected to the optical waveguide according to any one of the first to fourth aspects, wherein the fiber is inserted into the fiber insertion hole and the fiber buckles. The physical stress between the fiber and the waveguide is maintained by the generated stress.

[0020]

Embodiments of the present invention will be described below.

FIGS. 1 to 3 show a chip portion which is a component of an optical waveguide module with an optical connector according to the present invention. Here, an example of a chip shape for mounting a light receiving / emitting element as a chip is shown. 1 and 2, reference numeral 10 denotes a chip body, 11 denotes a planar waveguide substrate, 12 denotes a fitting recess,
13 is a wavelength filter insertion groove, 14 is a wavelength filter, 15
Is a waveguide, 16 is a die bonding terrace, 17 is a light receiving and emitting element terrace, 18 is a light receiving and emitting element, 19 is a mating terrace surface,
d indicates the effective width of the fitting recess, D indicates the chip width, and L indicates the chip length. As shown in FIG. 1, the fitting terrace surface 19 of the fitting concave portion 12 forms the terrace 17 for the light emitting / receiving element and the terrace 16 for the die bonding based on the precise mask alignment of submicron accuracy in the photolithography process of the substrate wafer. Processed simultaneously with fabrication. In the present embodiment, the fitting recess 12 has a V-shape, but the present invention is not limited to this.

Next, a brief description will be made on a method of manufacturing a PLC chip. First, the flat Si substrate 11 is patterned, and portions other than the mounting portion of the light receiving / emitting element 18 such as LD / PD are etched to a depth of about 30 μm. A glass layer serving as a lower cladding layer is formed thereon by a flame deposition method. Thereafter, flattening polishing is performed until Si of the LD / PD mounting portion is exposed on the surface. This surface becomes a height reference surface for the waveguide when the LD / PD is mounted. Subsequently, a second lower clad layer serving as a height adjusting layer and a core layer are deposited to a thickness of about 7 μm. After etching the core layer into a waveguide pattern,
Deposit the upper cladding layer. Subsequently, only the LD / PD mounting portion is etched until Si of the LD / PD mounting portion is exposed again. Finally, the electrode wiring of LD / PD and the solder for mounting are deposited.

The mounting of the light emitting / receiving element 18 such as an LD / PD
It is bonded and fixed to the mounting portion by solder reflow. See the following document for the method. [T.Hashimoto et a
l., "Hybrid integration of spot-size converted lase
r diode on planar lightwavecircuitplatform by pass
ive alignment technique, "IEEE Photon.Technol.Let
t., 8, No. 11, pp. 1504-1506, 1996., Inoue et al .; NTT R
& D Journal Vol. 46, No. 5, pp. 473-486 (1997)].

Next, the relationship between the effective width d of the fitting recess and the chip width D, which is particularly important as positional accuracy, will be described. A large number of chips shown in FIGS. 1 and 2 are usually processed and manufactured on a substrate wafer, and are formed into chips (thin rectangular parallelepipeds) by cutting the substrate in the final step. In the present embodiment, the dimensions of the chip body 10 are generally about 30 to 40 mm in chip length L and about 10 mm in chip width D. On the other hand, the fitting recess effective width d is processed at a position near the waveguide end so as to sandwich the waveguide end on the waveguide end surface. Since the pitch of the connection fibers is usually 250 to 500 μm, the fitting recess 12 is 1 mm.
It can be formed inside and outside at a position very close to the waveguide interval. The dimensional accuracy is simply proportional to the width of the chip. For example,
If the mask alignment accuracy is ± 0.2 μm / cm, the XY plane position accuracy on the substrate plane is ± 0.2 μm if the fitting recess 12 is 10 mm away, and therefore 1 / (1/3) if the marker is 1 mm apart. It can be reduced to 10. The Z direction is defined by the fitting terrace surface 19 of the fitting recess 12. Variations in the thickness of the waveguide chip are determined in the chip wafer fabrication process. The positional accuracy (height; Z-axis) with respect to the core portion is an accuracy of sub-μm, and the terrace of the present invention has the same accuracy because it is manufactured by the same process.

FIG. 3 shows an example of a connector portion of the optical waveguide module of the present invention. The connector module 21 shown in FIG. 3 has a fitting projection 22 that fits into the fitting recess 12 formed therein, and the fitting recess 12 and the fitting projection 22 fit into each other to position the chip. Is done. As described above, since the distance between the fitting concave portion and the distance from the waveguide connection surface is small, the connector module 21 is mounted on the end face of the chip main body 10 while the positional accuracy of the chip main body 10 is maintained, thereby forming an optical waveguide module. You.

FIG. 4 is a sectional view of an optical waveguide module with an optical connector according to the present invention. On the end surface side of the chip body 10 where the fitting recess 12 is provided, the fitting recess 1 is internally provided.
2 and a connector module (female portion) 21 having a fitting protrusion 22 corresponding to the connector module 2.
1 shows a state in which a connector plug section (male section) 32 having an optical fiber 31 inside is connected to one end of the connector 1. In the present invention, the fiber 3 is inserted into the fiber insertion hole 23.
1 is inserted and the physical contact between the fiber and the waveguide (Physical-c
ontact). The advantage of this type of connection is that the end face of the waveguide of the chip body 10 is covered with the first connector module 21 as compared with the conventional pin connection type module. For this reason, only the module hole 23 into which the optical fiber 31 is inserted has a defined positional accuracy, and there is no problem even if the dimensional accuracy of other outer portions is reduced by molding or the like.

[0027]

The present invention will now be described in detail with reference to Examples, but it should not be construed that the present invention is limited thereto.

Example 1 An optical waveguide module chip with an optical connector having the configuration shown in FIG. 1 was prepared by the following method. The chip width D: 5 mm, the chip length L: 15 mm, and the interval between the end faces of the two-core waveguide 15 was 500 μm. Wedge-shaped fitting recesses 12 were formed at 1.5 mm intervals on the end faces of the waveguide at 500 μm intervals, and equilateral triangular recesses of 500 μm were formed on the chip terrace surfaces to form fitting terrace surfaces 19. The depth from the overcladding of the chip to the terrace surface was 50 μm.

The connector portion of the connector module 21 was formed by transfer molding using a pellet obtained by mixing a quartz filler with a thermosetting resin. Chip body 1
The outline of the part where 0 is inserted is the width + 20 μm, the thickness is the insertion part + 50 μm, the tip + 0, minus 2 μ
As shown in FIG. 5, a slight taper was provided in the chip insertion direction as a tolerance of m. As a result, with respect to the variation in the chip body 10, the fitting protrusion 22 was completely fitted into the fitting recess 12 including the deformation of the resin of the connector module 21 at an insertion pressure of about 2 kgf between the chip tip and the connector module. . The diameter of the fiber insertion hole 23 was 127 μm plus 1, minus 0 μm. The dimensional tolerance of this hole diameter is
The same conditions as those of the MT type optical connector for performing the same resin molding were used. In this state, a UV curing resin was applied to the rear part of the optical connector portion, and the chip main body 10 and the connector module 21 were fixed by irradiating ultraviolet rays for 5 minutes while the fitting protrusion 19 was in close contact with the fitting concave portion 12. . Next, two carbon-coated fibers are arranged at an interval of 500 μm, and the physical contact type optical connector plug portion (male portion) 32 whose tip portion is held so as to protrude by 30 mm is pressed in parallel by a jig, and An optical fiber 32 was inserted into the optical waveguide module to produce an optical waveguide module. The loss in the internal circuit of the waveguide was measured in advance, and the measured loss was obtained by subtraction. When the optical loss was measured, the connection loss was 0.27 dB on average, and the return loss was 4 with a yield of 90% or more.
It exhibited characteristics of 0 dB or more.

[0030]

As described above, the optical waveguide module with the optical connector according to the present invention uses the fitting type self-alignment technology and the physical contact type optical connector technology as compared with the conventional optical waveguide module. Has advantages. (1) Since active alignment is not performed on the connector connection portion, the manufacturing time and the manufacturing cost can be significantly reduced. (2) The connection fiber can be freely attached and detached. (3) Since the connector connecting portion of the module can be manufactured by simple resin molding, it is excellent in mass productivity and cost.

[Brief description of the drawings]

FIG. 1 is a plan view of a chip body according to the present invention.

FIG. 2 is a perspective view of a chip body according to the present invention.

FIG. 3 is a plan view showing a fitted state of a chip body and a connector module according to the present invention.

FIG. 4 is a cross-sectional view of the optical waveguide module with an optical connector according to the present invention at the time of connection.

FIG. 5 is a cross-sectional view when the optical waveguide module with the optical connector according to the embodiment of the present invention is connected.

FIG. 6 is a diagram showing a connection example of a conventional optical waveguide module.

FIG. 7 is a diagram showing a connection example of a conventional optical waveguide module.

FIG. 8 is a diagram showing a waveguide section of a conventional optical waveguide connector with pins.

FIG. 9 is an enlarged image view of an anisotropic (selective) etching surface of a Si substrate.

FIG. 10 is a diagram illustrating an image of occurrence of unevenness in groove depth due to substrate warpage in a substrate dicing step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Planar waveguide board 12 Fitting recess 13 Wavelength filter insertion groove 14 Wavelength filter 15 Waveguide 16 Die bond terrace 17 Light receiving / emitting element terrace 18 Light receiving / emitting element 19 Fitting terrace surface 21 Connector module (female part) 22 Fitting projection Part 23 Connection fiber insertion hole 31 Optical fiber 32 Optical connector plug part (male part) 33 Buckling part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuichiro Asakawa 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Yasufumi Yamada 3-192 Nishi Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Toshikazu Hashimoto 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Kuniharu Kato 3-192, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation (72) Inventor Michiyuki Amano 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (5)

[Claims] 1. An optical waveguide component comprising an optical waveguide formed on a flat substrate and a fiber connection member having a fiber insertion hole provided at an end of the optical waveguide, the optical waveguide component being provided at a predetermined position of the optical waveguide. The optical axis of the optical waveguide and the optical fiber passing through the fiber insertion hole are adjusted by fitting the fitted fitting recess and the fitting projection provided at a predetermined position of the fiber connecting member fitted to the fitting recess. An optical waveguide component, comprising: 2. The light guide according to claim 1, wherein the fitting recess of the optical waveguide faces the end face of the optical waveguide, and has the substrate surface and the optical waveguide side surface which appear after removing the optical waveguide. Wave parts. 3. The optical waveguide component according to claim 1, wherein the fitting protrusion of the fiber connection member is formed integrally with the fiber connection member. 4. The optical waveguide component according to claim 1, wherein the fiber connecting member is a resin molded product. 5. An optical waveguide module in which a fiber is connected to the optical waveguide according to claim 1, wherein the fiber is inserted into the fiber insertion hole and the fiber is buckled by stress generated between the fiber and the waveguide. An optical waveguide module characterized by maintaining physical contact with the optical waveguide module.