JP2511287B2 - Optical adhesive and optical component using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an optical adhesive which is indispensable for producing an optical component and an optical component using the same.

[Conventional technology]

Conventionally, as this kind of optical adhesive, a compound represented by the following general formula II However, it was difficult to drastically change the refractive index control range because of the low fluorine content.

Further, there has been a silicone resin as a conventional optical adhesive, but since the silicone resin has drawbacks such as poor adhesiveness and poor mechanical properties, it cannot be used for manufacturing an optical component by laminating optical members.

Further, as a resin whose refractive index can be adjusted, there is polymethylmethacrylate introduced with a fluorine atom, but it has a high viscosity and is inferior in adhesiveness and cannot be used for manufacturing an optical component by laminating optical members.

[Problems to be Solved by the Invention] In order to solve these drawbacks, the present invention provides a new optical adhesive capable of adjusting the refractive index in a wide range, bonding the optical members at room temperature in a short time, and It is characterized by manufacturing optical parts using this, and its purpose is to use it as an adhesive to reduce the return loss, and to use it as a coating agent to reduce the waveguide loss and to achieve high performance and high productivity of various optical components. It is to provide parts at low cost.

[Means for solving the problem]

Briefly describing the present invention, the first invention of the present invention relates to an optical adhesive, which is represented by the following general formula I: [In the formula, Z is (Y is H or CH ₃ group), M is Or n represents 0 or any positive number].

A second invention of the present invention is an invention relating to an optical component, characterized in that the optical adhesive of the first invention is used for bonding transparent optical members.

A third invention of the present invention relates to another optical component, which is characterized in that a transparent optical member is coated with the optical adhesive of the first invention.

An adhesive whose refractive index can be adjusted is effective in reducing reflection attenuation when used for bonding optical members. When the amount of reflection is large, the reflected light returns to the light source, disturbs the light source, and causes noise, which causes a problem in reliability of optical communication. Therefore, in order to ensure the reliability of optical communication, it is desirable that the return loss is 30 dB or more, and conventionally, the end facet reflection was reduced by laminating optical glass whose end face was obliquely polished. For this reason, loss of the end face is unavoidable, but the use of the optical adhesive of the present invention can reduce the amount of light reflection without the need for oblique polishing. The reflectance r when an optical member having a refractive index of n ₀ and an optical member having a refractive index of n ₂ are bonded together with an adhesive having a refractive index of n ₁ and a thickness of d can be obtained by Fresnel's formula.

Here, the reflectance r differs depending on the thickness of the adhesive. It is difficult to control the thickness of the adhesive on the order of wavelength, and the productivity is also poor. Therefore, if the condition that maximizes the formula (1) is sought regardless of the thickness d of the adhesive, The reflection does not become larger than the above. Therefore, the return loss RL is defined as RL = 10log (r _max ) [dB] (2). This return loss is a value at a wavelength used in optical communication (for example, 1.3 μm), and is different from the refractive index n _D for the normally used sodium D line (λ = 0.589 μm). When the end surface (refractive index 1.462 at 1.3 .mu.m) optical fiber terminates in an adhesive having various refractive index n _D, to determine the refractive index n _D of the adhesive reflection is minimized at a wavelength of 1.3 .mu.m, n _D = N (λ = 1.3 μm) +0.016 (3) Therefore, the equation (3) can be used to convert the values of n (λ = 1.3 μm) and n _D. In the following examples, the relationship between the refractive index and the return loss at λ = 1.3 μm was obtained, and the value of n _D actually measured from the equation (3) was used to calculate n.
The value of (λ = 1.3 μm) is calculated.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 FIG. 1 is a graph showing the effect of one example of the present invention, in which the following general formula A: A compound represented by (hereinafter CHE _P abbreviated) with other compounds and by mixing as shown below optical adhesive (A1) using a metal halide lamp at room temperature for 1
After irradiating for 10 minutes (10mW), the CHE _P content dependence of the refractive index after photo-curing is shown as ADE _P / CHE _P (part by weight, horizontal axis) and refractive index ▲ n ²⁵ _D
▼ (vertical axis).

As is apparent from FIG. 1, it was possible to adjust the refractive index (n ²⁵ _D ) from 1.450 to 1.590 by using an optical adhesive containing at least the compound represented by the general formula A.

Example 2 Figure 2 an alien a graph showing the effect of an embodiment of the present invention, CHE _P and other compounds and a mixture thereof comprising an optical adhesive as shown below a metal halide lamp at room temperature (A2) After irradiating for 1 minute (10 mW), the CHE _P content dependence of the refractive index after photocuring was calculated as AFE _P / CHE _P (part by weight, horizontal axis) and refractive index ▲ n ²⁵ _D ▼ (vertical axis). It is shown in the relationship of.

As is apparent from FIG. 2, the refractive index could be adjusted from 1.447 to 1.529 by using the optical adhesive containing at least the compound represented by the above general formula A.

Example 3 FIG. 3 is a graph showing the effect of one example of the present invention, in which the following general formula B: A compound represented by (hereinafter CHE _P A abbreviated) with other compounds and by mixing as shown below optical adhesive (B1) using a metal halide lamp at room temperature for 1
Minutes (10 mW) is irradiated, the refractive index after the photocured CHE _P A
The content dependent AFE _P A / CHE _P A (parts by weight, the horizontal axis) and refractive index ▲
n ²⁵ _D ▼ (vertical axis).

As is clear from FIG. 3, the optical adhesive containing at least the compound represented by the general formula B has a refractive index ▲ n ²⁵ _D ▼.
I was able to adjust from 1.467 to 1.522.

Example 4 The following general formula C: After the photo-curing was performed by irradiating an optical adhesive obtained by mixing the compound represented by (1) (hereinafter abbreviated as DPE _P ) and other compounds as follows with a metal halide lamp at room temperature for 1 minute (10 mW). The refractive index range was measured.

As a result, it was possible to adjust the refractive index (n ²⁵ _D ) from 1.489 to 1.513 by using the optical adhesive containing the compound represented by the general formula C.

Example 5 The following general formula D: An optical adhesive prepared by mixing the compound represented by (hereinafter abbreviated as DPE _P A) and other compounds as follows at room temperature with a metal halide lamp for 1 minute (10 m
W) Irradiation was performed and the refractive index after photocuring was measured.

As a result, the refractive index (n ²⁵ _D) could be adjusted from 1.494 to 1.497 by using the optical adhesive containing the compound represented by the general formula D.

Example 6 FIG. 4 is a schematic cross-sectional view of an example of an optical component of the present invention. Reference numeral 1 is an optical fiber adhered and fixed to a ferrule and the end surface is ground, 2 is an optical adhesive, and 3 is an antireflection film. Attached optical glass. FIG. 5 shows that the above-mentioned 1 is a single mode optical fiber, 3 is a BK-7 glass with an antireflection film, and the optical adhesive of the present invention is used to bond them together, followed by photocuring to obtain the maximum value of the return loss at 1.3 μm ( The value obtained by changing the thickness of the optical adhesive to obtain the maximum reflected light intensity (the same applies below) is the result of the refractive index n (horizontal axis) and the return loss (dB, vertical axis) of the optical adhesive. It is a graph shown by a relation.

The refractive index range (λ = 1.3 μm) of the optical adhesive is 1.450 ≦ n ≦ 1.524, that is, the refractive index n _D normally used according to the formula (3).
When converted to 1.466 ≦ ▲ n ²⁵ _D ▼ ≦ 1.540, a return loss of 30 dB or more can be secured.

Example 7 FIG. 6 is a schematic sectional view of an example of an optical component of the present invention, in which reference numeral 4 is an optical filter, 2 is an optical adhesive, and 5 is an optical glass. FIG. 7 shows that the optical filter made of BK-7 glass is used as 4 above, and BK-7 glass is used as 5 and the optical adhesive of the present invention is used for bonding and photocuring. The maximum value of the return loss at 1.3 μm is shown in FIG. The obtained result is the refractive index n of the optical adhesive.
6 is a graph showing the relationship between (horizontal axis) and return loss (dB, vertical axis). Refractive index range of optical adhesive (λ = 1.3 μm)
That is, 1.456 ≦ n ≦ 1.552, that is, it is converted to n _D by the equation (3), and 1.472 ≦ ▲ n ²⁵ _D ▼ ≦ 1.568, so that the return loss of 30 dB or more can be secured.

Example 8 FIG. 8 is a schematic sectional view of an example of an optical component of the present invention, in which reference numeral 6 is a single mode optical fiber, 2 is an optical adhesive, and 7 is a ferrule. In FIG. 9, the optical adhesive of the present invention is used as the above item 2, and the single mode optical fiber and the single mode optical fiber are bonded and photocured,
6 is a graph showing the result of obtaining the maximum reflection attenuation amount at 1.3 μm as a relationship between the refractive index n (horizontal axis) of the optical adhesive and the reflection attenuation amount (dB, vertical axis). Refractive index range of optical adhesive (λ
= 1.3 μm) is 1.450 ≦ n ≦ 1.496, that is, it is converted to n _D by the equation (3), and 1.466 ≦ ▲ n ²⁵ _D ▼ ≦ 1.512, so that a return loss of 30 dB or more can be secured.

Example 9 FIG. 10 is a schematic sectional view of an example of an optical component of the present invention, in which reference numeral 8 is a multimode optical fiber, 2 is an optical adhesive, and 7 is a ferrule. FIG. 11 shows that the optical adhesive of the present invention is used as the above 2 and the multimode optical fiber and the multimode optical fiber are brought into contact with each other and photocured.
It is a graph which shows the result of having calculated | required the maximum value of the return loss in (micrometer) with the refractive index n (horizontal axis) of an optical adhesive, and the return loss (dB, vertical axis). Refractive index range of optical adhesive (λ = 1.
3 μm) is 1.450 ≦ n ≦ 1.508, that is, it is converted to n _{D according} to the equation (3), and by 1.466 ≦ ▲ n ²⁵ _D ▼ ≦ 1.524, a return loss of 30 dB or more can be secured.

Example 10 FIG. 12 is a perspective view of an example of the optical component of the present invention, in which reference numeral 9 is a transparent optical fiber, and 2 is an optical adhesive having a refractive index smaller than that of the transparent optical fiber 9.

The optical fiber 2 can be manufactured by applying the optical adhesive 2 on the optical fiber 9 and irradiating it with light to cure the optical adhesive 2. As a transparent optical fiber, polymethylmethacrylate (PMMA) (refractive index 1.4 at λ = 0.663 μm)
9), polycarbonate (refractive index 1.5 at λ = 0.663μm)
The optical adhesive of the present invention can be applied to transparent fibers having various refractive indexes such as 9) and quartz (refractive index n _D 1.463).

Example 11 FIG. 13 is a perspective view of an example of an optical component of the present invention. Reference numeral 11 is an optical fiber, 12 is an optical coupling portion formed by bundling and twisting optical fibers, and 2 is an optical adhesive. It is an agent. By making the refractive index of the optical adhesive of the present invention smaller than that of the optical fiber, it is possible to form a star cutler having a small waveguide loss.

Example 12 FIG. 14 is a process drawing of the production of an example of the optical component of the present invention, in which reference numeral 13 is a glass substrate, 14 is an optical waveguide core layer, and 15 is a cladding layer. FIG. 14 (a) shows a state in which an optical waveguide core layer 14 having a refractive index larger than that of the glass substrate 13 is applied on the glass substrate (refractive index n) 13 to a predetermined thickness using the optical adhesive of the present invention and cured. Show. FIG. 14 (b) is 14 of FIG. 14 (a).
The optical waveguide core layer is etched into a predetermined pattern to form an optical waveguide core. FIG. 14 (c) shows a state in which the cladding layer 15 having a refractive index smaller than that of the optical waveguide core is applied and cured using the optical adhesive of the present invention. The optical waveguide can be easily formed by such a procedure.

Example 13 FIG. 15 is a process drawing of the production of an example of the optical component of the present invention, wherein reference numerals 2, 11, 13, and 14 are as described above, 16 is a buffer layer, and 17 is an optical fiber guide. In FIG. 15 (a), an optical adhesive having a smaller refractive index than the core optical adhesive is applied on the glass substrate 13 to a predetermined thickness and then cured to form a buffer layer 16, and then the refractive index is set higher than that of the buffer layer. The optical waveguide core layer 14 having a large rate is applied to a predetermined thickness using the optical adhesive of the present invention and cured. Figure 15 (b) is Figure 15 (a).
16 shows a state in which the optical fiber guide 17 is formed simultaneously with the formation of the optical waveguide core by etching the buffer layer and the optical waveguide core layer of 14 in a predetermined pattern shape. FIG. 15 (c) shows a state in which the end face of the optical fiber 11 is aligned with the optical waveguide along the optical fiber guide. FIG. 15 (d) shows a state in which the optical adhesive 2 of the present invention having a refractive index smaller than that of the optical waveguide core layer 14 is applied and cured. As a result, the optical waveguide and the optical fiber can be connected at the same time when the cladding layer of the optical waveguide is formed.

Example 14 FIG. 16 is a perspective view of a two-stage branch circuit which is one example of the present invention, and was manufactured according to the process chart shown in FIG.
FIG. 14 (a) shows a state in which an optical waveguide core layer 14 having a refractive index larger than that of the glass substrate 13 is formed on a glass substrate (refractive index n) 13 by melting Ge-doped soot-shaped deposited glass to a predetermined thickness. Indicates. FIG. 14 (b) shows a state in which the optical waveguide core layer of FIG. 14 (a) is etched into a predetermined shape to form an optical waveguide core. FIG. 14 (c) shows a state in which the cladding layer 15 having a refractive index smaller than that of the optical waveguide core is applied and cured using the optical adhesive of the present invention. The optical waveguide can be easily formed by such a procedure.

The two-stage branch circuit shown in FIG. 16 was produced by the above method, and the refractive index n _D (after curing) of the optical adhesive of the present invention was 1.452.
The coating was then adjusted to a wavelength of 1.3 μm.
It was found that a loss of 10 dB was obtained and that the loss reduction effect was extremely large.

Example 15 One example of the optical component of the present invention was produced according to the process chart shown in FIG. FIG. 15 (a) shows a glass substrate 13 on which a buffer layer having a smaller refractive index than the optical waveguide core layer is formed to a predetermined thickness, and a soot-shaped deposited glass doped with Ge having a larger refractive index than the buffer layer. A state in which the optical waveguide core layer 14 is melted to have a predetermined thickness is shown. Figure 15 (b) shows the number 15
FIG. 16A shows a state in which the buffer layers 16 and 14 and the optical waveguide core layer 16 are etched into a predetermined pattern shape to form an optical waveguide and an optical fiber guide 17 at the same time. 15th
FIG. 6C shows a state in which the end face of the optical fiber 11 is aligned with the optical waveguide along the optical fiber guide. FIG. 15 (d) shows a state in which the optical adhesive 2 of the present invention having a refractive index smaller than that of the optical waveguide core layer 14 is applied and cured. As a result, the optical waveguide and the optical fiber can be connected at the same time when the cladding layer of the optical waveguide is formed.

〔The invention's effect〕

As described above, the optical adhesive of the present invention has an extremely wide range of refractive index adjustment, enables bonding and coating of various optical members, and easily manufactures an optical component having excellent optical characteristics at room temperature in a short time. There is an advantage.

[Brief description of drawings]

1, 2, and 3 are graphs showing the effect of the optical adhesive of the present invention on the refractive index, and FIGS. 4, 6, 8, and 10 show the optical components of the present invention. Schematic sectional views of one example, FIG. 5, FIG. 7, FIG. 9 and FIG. 11 are graphs showing the effects of the optical components shown in the preceding figures, respectively, and FIG. 12, FIG. 13, FIG. FIG. 14 is a perspective view of an example of the optical component of the present invention, and FIGS. 14 and 15 are process diagrams for manufacturing the example of the optical component of the present invention. 1: Optical fiber with edge polished, 2: Optical adhesive, 3: Optical glass with antireflection film, 4: Optical filter, 5: Optical glass, 6: Single mode optical fiber, 7: Ferrule, 8: Multimode optical fiber , 9: transparent optical fiber, 11: optical fiber, 1
2: Optical coupling part, 13: Glass substrate, 14: Optical waveguide core layer, 15:
Cladded layer, 16: buffer layer, 17: optical fiber guide

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Claims (3)

(57) [Claims] (1) The following general formula (I): [In the formula, Z is Group (Y is H or CH ₃ group), M is Or n represents 0 or an arbitrary positive number]. An optical adhesive comprising a compound represented by the formula: 2. An optical component using the optical adhesive according to claim 1 for bonding transparent optical members. 3. An optical component comprising a transparent optical member coated with the optical adhesive according to claim 1.