JP3134677B2 - Resin embedded optical waveguide device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-embedded optical waveguide device used for optical communication.

[0002]

2. Description of the Related Art In the field of optical communication, technical development for constructing an optical subscriber system capable of multimedia has been actively conducted. In an optical subscriber system, an optical multiplexing / demultiplexing device that splits light of one optical fiber into a plurality of lights or combines light of a plurality of optical fibers into one is indispensable. Optical waveguide devices are small, high-performance devices. However, the optical subscriber system requires low cost and high reliability because this device must be installed in a general home.

FIGS. 7 and 8 are external perspective views of a conventional optical waveguide device.

As shown in FIG. 1, an optical waveguide device comprises an optical waveguide substrate 11 having a lightwave circuit 12 formed on a substrate, and an optical fiber array 13 in which optical fibers 14 are arranged and fixed.
The optical waveguide substrate 11 and the optical fiber array 13
Are aligned and optically aligned to be bonded and fixed.

[0005] The optical waveguide element 10 is used in optical communication, for example, for joining and branching signals of a plurality of optical fibers. Since the optical waveguide substrate 11 and the optical fiber array 13 are formed of a brittle material such as quartz glass or single-crystal silicon, the optical waveguide substrate 11 and the optical fiber
Are stored in a package 21 as shown in FIG. This package 21
Is formed by cutting a metal, into which the optical waveguide element 10 is inserted and fixed with an adhesive.

[0006]

However, the optical waveguide device shown in FIG. 8 has the following problems.

(1) The package is expensive because it is made of metal.

(2) The optical waveguide elements must be inserted into the package one by one and bonded and fixed, which requires time and effort in manufacturing, is expensive, and is not suitable for mass production.

(3) Since the package is made of metal, it becomes heavy,
For example, if the optical waveguide element containing the metal package hangs on the optical fiber due to careless handling,
Excessive stress is applied to the optical fiber, and in the worst case, the optical fiber is broken.

(4) An ultraviolet curing adhesive having a refractive index matching effect is widely used for bonding and fixing the optical waveguide substrate and the optical fiber array. However, ordinary UV curable adhesives are vulnerable to high temperature and high humidity. For this reason, it is necessary to use a special UV-curable adhesive that is resistant to high temperature and high humidity, which is expensive.

An object of the present invention is to solve the above-mentioned problems and to provide an optical waveguide device which is inexpensive, has excellent mass productivity, and has high reliability, and a method of manufacturing the same.

[0012]

In order to achieve the above object, the present invention provides an optical waveguide substrate having a lightwave circuit formed on a substrate, and an optical fiber array in which optical fibers are aligned and fixed. The optical waveguide substrate and the optical fiber array are adhered and fixed in alignment with the optical axis, and the adhesive portion between the optical waveguide substrate and the optical fiber array is coated around the periphery thereof.
In the optical waveguide element directly covered by the resin
The optical waveguide substrate contacts the resin at the lightwave circuit
And directly in contact with the resin in parts other than the optical circuit
It is embedded .

Further , the present invention provides the above-mentioned light wave circuit,
A sponge is attached above the lightwave circuit so that it does not touch
The sponge and the optical waveguide substrate are
It may be physically embedded in the resin .

Further , the present invention provides the above-mentioned light wave circuit,
Unevenness on the back surface above the lightwave circuit to prevent contact
To cover the light guide.
Even if the waveguide substrate is integrally embedded in the resin
Good .

In addition, in the present invention, in addition to the above constitution, the resin used for embedding the bonded and fixed portion may be any of thermosetting epoxy resin, polyphenylene sulfide and liquid crystal polymer.

Also, the above-mentioned resin-embedded optical waveguide device
Bonded and fixed the optical waveguide substrate and the optical fiber array
Place things in the mold, inject molten resin and cure
Can be manufactured.

Here, a sponge or a cap is placed above the lightwave circuit.
When exposing the space above the lightwave circuit without providing a
Inject molten resin so as not to contact the lightwave circuit
Need to be converted.

Further , when the molten resin is injected and cured.
In this case, the molten resin is injected and cured by transfer molding or injection molding.

[0019]

According to the above construction, an optical waveguide element in which an optical waveguide substrate and an optical fiber array are aligned with respect to an optical axis and adhered and fixed is arranged in a mold, and is easily bonded by injecting and curing a molten resin. The fixing portion can be embedded in the resin, and the resin-embedded optical waveguide element can be easily manufactured. By processing a plurality of cavities in a mold, a large number of resin-embedded optical waveguide elements can be manufactured at one time, and excellent mass productivity can be realized and low cost can be realized.

By forming the package covering the optical waveguide element with a resin, it becomes lighter than the optical waveguide element covered with the metal package. For example, the resin embedded type optical waveguide element hangs on the optical fiber due to careless handling. Even when the optical fiber is not overstressed,
There is no breakage of the optical fiber.

Since the adhesive fixing portion made of the ultraviolet curing resin has an airtight structure covered with the resin, it is possible to prevent the adhesive fixing portion from absorbing moisture under high temperature and high humidity.

When the entire optical waveguide and the optical fiber array are embedded in a resin, the molding shrinkage of the resin acts as a compressive force on the adhesive fixing portion between the optical waveguide substrate and the optical fiber array. Even if the adhesive strength is weakened due to moisture absorption, the adhesive surface does not peel off and the optical axis of the optical fiber and the waveguide do not shift.

Further, by forming the optical waveguide at a distance from the resin, no compressive force of the resin is applied to the optical waveguide, and the characteristics are not deteriorated.

Therefore, high reliability can be obtained even when an inexpensive ultraviolet-curable adhesive is used.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an external perspective view showing an embodiment of the resin-embedded optical waveguide device of the present invention, and FIG. 2 is a perspective view of the optical waveguide device used in the resin-embedded optical waveguide device shown in FIG. It is an external appearance perspective view.

The optical waveguide substrate 11 shown in FIG. 2 has a 1 × 2 multiplexer / demultiplexer as an optical circuit formed on the substrate.
This is for distributing the light incident from one optical fiber 32 to two optical fibers 33 or for multiplexing the light incident to two optical fibers 33 to one optical fiber 32.

The optical waveguide element 30 includes optical fibers 32, 3
3 is an optical fiber array 3 having a V-groove formed in quartz glass.
4 is fixed with an ultraviolet-curable adhesive, the end surface 35 is polished, and then fixed to the optical waveguide substrate 11 with an ultraviolet-curable adhesive.

The optical waveguide device 30 thus obtained
Is placed in a mold 40 shown in FIG. The mold 40 includes a pin 41 for holding the optical waveguide element 30 and a space (cavity) formed so as to surround the optical waveguide element 30.
After the optical waveguide element 30 is disposed, the molten resin is injected from a resin injection port (gate) 43 in the cavity 42 and cured to form a resin-embedded optical waveguide element 50 as shown in FIG. can get. In the figure, reference numeral 51 denotes a resin, 5
2 is a pin hole. FIG. 3 is a sectional view of a mold for manufacturing the resin-embedded optical waveguide device shown in FIG.

Next, the operation of the embodiment will be described.

Optical waveguide substrate 11 and optical fiber array 34
The optical waveguide element 30 having the optical axis aligned and fixed is disposed in the mold 40, and the molten resin is injected and cured to embed the adhesive fixing portion in the resin. The element 50 can be easily manufactured. Further, by processing a plurality of cavities in the mold, a large number of optical waveguide elements can be manufactured at one time, and excellent mass productivity can be achieved and low cost can be realized.

By forming the package covering the optical waveguide element 30 with a resin, the package becomes lighter than the optical waveguide element covered with the metal package. For example, the resin-embedded optical waveguide element 50 hangs on the optical fiber 33 due to careless handling. Even if the optical fiber 33 is in the state of being bent, no excessive stress is applied to the optical fiber 33 and the optical fiber 33 is not broken.

Since the adhesive fixing portion made of the ultraviolet curing resin has an airtight structure covered with the resin, it is possible to prevent the adhesive fixing portion from absorbing moisture under high temperature and high humidity.

When the entire optical waveguide substrate 11 and the optical fiber array 34 are embedded in the resin, the molding contraction force of the resin acts as a compressive force on the adhesive fixing portion between the optical waveguide substrate 11 and the optical fiber array 34. Therefore, even if the adhesive absorbs moisture and the adhesive strength is weakened, the adhesive surface does not peel off, and the optical axis of the optical fiber 33 and the optical waveguide substrate 11 does not shift.

Therefore, even if an inexpensive UV-curable adhesive is used, a highly reliable resin-embedded optical waveguide device can be obtained.

In this embodiment, (1) a resin-embedded optical waveguide device using a thermosetting epoxy resin by transfer molding
(2) Embedded resin optical waveguide device using polyphenylene sulfide resin by injection molding (3) Embedded resin optical waveguide device using liquid crystal polymer by injection molding (4) Resin using polyethylene terephthalate resin by injection molding Four types of resin-embedded optical waveguide elements, namely, embedded optical waveguide elements, and optical waveguide elements having a package structure according to the prior art were produced.

In order to evaluate the reliability of the resin-embedded optical waveguide device and the optical waveguide device, 80 ° C. × 95% RH
Was subjected to a high-temperature and high-humidity test, and a change in the amount of light transmitted was observed.

The structure of the prior art requires three hours in 500 hours.
dB decreased. In the case of using polyethylene terephthalate resin, the resin becomes brittle due to moisture absorption,
After a lapse of time, a crack was formed in a weld line during molding (a portion where the ends of the flow of the molten resin flow in the mold).

In another resin-embedded optical waveguide device of this embodiment, the change in the amount of transmitted light is not more than 0.2 hours after the elapse of 2000 hours.
It was within 1 dB, and it was confirmed that the device had high reliability.

In this embodiment, the resin used is of a grade reinforced with a glass filler, but the presence or absence of the filler, the material, the filling rate and the like are not limited.

As described above, the resin-embedded optical waveguide device of this embodiment can be applied to a system or a product requiring an optical multiplexing / demultiplexing device, for example, an optical fiber gyro.

As shown in FIG. 9, the lightwave circuit portion of the optical waveguide substrate is a Mach-Zehnder 1 × 2 optical multiplexer / demultiplexer 6.
In the case of 1, there is a problem that the branching ratio, which was approximately 1: 1 before embedding the optical multiplexer / demultiplexer 61 in the resin, changes to 1: 1. Will happen. This problem occurs in any of the above-mentioned resins.

Accordingly, the present inventors have proposed a resin-embedded optical waveguide element in which the characteristics are not deteriorated even if the lightwave circuit section is of a Mach-Zehnder type.

FIG. 4 is an external perspective view of another embodiment of the resin-embedded optical waveguide device of the present invention.

The difference from the resin-embedded optical waveguide device shown in FIG. 1 is that the resin covering the optical waveguide device is formed separately from the Mach-Zehnder optical circuit portion.

As shown in FIG. 4, the optical waveguide element is covered with the resin 51 so that the Mach-Zehnder circuit upper space 91 is exposed. In such a resin-embedded optical waveguide device, since the upper portion of the Mach-Zehnder type optical multiplexer / demultiplexer 61 (FIG. 9) is opened, a compressive force is prevented from being applied to the circuit due to resin molding shrinkage. The characteristics do not deteriorate.

Therefore, a resin-embedded optical waveguide device which is inexpensive, has high productivity, and has high reliability can be obtained.

In this embodiment, (1) the cross section of one of the pins 41 for holding the optical waveguide element of the mold 40 shown in FIG. 3 is made larger than the size of the Mach-Zehnder type optical multiplexer / demultiplexer 61, A resin-embedded optical waveguide element (2) arranged above the Mach-Zehnder type optical multiplexer / demultiplexer 61 so that the resin does not flow above the Mach-Zehnder type optical multiplexer / demultiplexer 61 during molding, as shown in FIG. A resin-embedded optical waveguide in which an optical waveguide element 70 having a sponge 71 adhered above a Mach-Zehnder type optical multiplexer / demultiplexer 61 is integrally embedded in a resin so that the resin does not contact the Mach-Zehnder type optical multiplexer / demultiplexer 61. Element (3) An optical waveguide element 80 in which a cap 81 having irregularities on the back surface not shown in FIG. 6 is placed over a Mach-Zehnder type optical multiplexer / demultiplexer 61 is integrally embedded in resin. Mach-Zehnder type optical demultiplexer 6
A resin-embedded optical waveguide element which was made not to contact with No. 1 was manufactured. The appearance according to (1) is as shown in FIG. 4, and the appearance according to (2) and (3) is the same as that shown in FIG. 5 and 6 are external perspective views of an optical waveguide device used in another embodiment of the resin-embedded optical waveguide device of the present invention.

As a result, there is no deterioration in the characteristics before and after embedding in any of the above-mentioned elements, and the temperature is 80 ° C. × 95% R
In the high-temperature and high-humidity test of H, the change in the amount of transmitted light was within 0.1 dB even after lapse of 2000 hours, confirming that the device had high reliability.

In this embodiment, a sponge is used, but a soft rubber or the like may be used instead of the sponge. The effect is obtained.

Further, in this embodiment, the case where the light wave circuit portion of the optical waveguide substrate is a Mach-Zehnder circuit is described. It is useful in.

[0052]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Since the portion where the optical waveguide substrate and the optical fiber array are aligned with the optical axis and adhered and fixed is embedded in the resin, the resin embedded optical waveguide device which is inexpensive, has excellent mass productivity, and has high reliability. Is obtained.

(2) When the lightwave circuit of the optical waveguide substrate is of a Mach-Zehnder type, the lightwave circuit portion is formed apart from the resin, so that a resin-embedded optical waveguide element without deterioration in characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing one embodiment of a resin-embedded optical waveguide device of the present invention.

FIG. 2 is an external perspective view of an optical waveguide element used in the resin-embedded optical waveguide element shown in FIG.

FIG. 3 is a sectional view of a mold for manufacturing the resin-embedded optical waveguide element shown in FIG.

FIG. 4 is an external perspective view of another embodiment of the resin-embedded optical waveguide device of the present invention.

FIG. 5 is an external perspective view of an optical waveguide element used in another embodiment of the resin-embedded optical waveguide element of the present invention.

FIG. 6 is an external perspective view of an optical waveguide element used in another embodiment of the resin-embedded optical waveguide element of the present invention.

FIG. 7 is an external perspective view of a conventional optical waveguide device.

FIG. 8 is an external perspective view of a conventional optical waveguide element.

FIG. 9 is an external perspective view of an optical waveguide element in a case where a light wave circuit section of the optical waveguide substrate is of a Mach-Zehnder type.

[Explanation of symbols]

 11 Optical waveguide substrate 33 Optical fiber 34 Optical fiber array

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-45531 (JP, A) JP-A-7-140337 (JP, A) JP-A-5-66318 (JP, A) JP-A-5-66318 27139 (JP, A) JP-A-7-92342 (JP, A) JP-A-7-198990 (JP, A) JP-A-7-209549 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/30 G02B 6/12

Claims (6)

(57) [Claims] An optical waveguide substrate having a lightwave circuit formed on a substrate and an optical fiber array in which optical fibers are aligned and fixed, wherein the optical waveguide substrate and the optical fiber array are aligned and aligned with each other. It is fixed, and the adhesive portion with the optical waveguide substrate and the optical fiber array is covered and molded around it.
In the optical waveguide element directly covered with the resin,
The optical waveguide substrate is in contact with the resin at the lightwave circuit part.
Directly in contact with the resin in the area other than the optical circuit and buried in the resin
Resin embedded type optical waveguide device characterized by being written. 2. The method according to claim 1, wherein the resin does not contact the lightwave circuit.
A sponge is attached above the lightwave circuit,
The sponge and the optical waveguide substrate are integrally formed in the resin.
The resin-embedded optical waveguide device according to claim 1, wherein the optical waveguide device is embedded in a substrate. 3. The method of claim 1, wherein the resin does not contact the lightwave circuit.
A cap is placed on the lightwave circuit above the lightwave circuit.
The cap and the optical waveguide substrate are integrally embedded in the resin.
The resin-embedded optical waveguide device according to claim 1, wherein the optical waveguide device is embedded. 4. The resin is a thermosetting epoxy resin.
The resin-embedded optical waveguide device according to claim 1 . 5. The method according to claim 1 , wherein the resin is polyphenylene sulfide.
The resin-embedded optical waveguide device according to claim 1, wherein: 6. The method according to claim 1, wherein said resin is a liquid crystal polymer.
4. The resin-embedded optical waveguide device according to any one of items 1 to 3 .