WO2022131634A1

WO2022131634A1 - Optical device for wavelength division multiplexing that eliminates defects caused by outgas

Info

Publication number: WO2022131634A1
Application number: PCT/KR2021/018070
Authority: WO
Inventors: 강정규
Original assignee: 주식회사 에스엘테크놀로지
Priority date: 2020-12-16
Filing date: 2021-12-02
Publication date: 2022-06-23

Abstract

Disclosed is an optical device for wavelength division multiplexing that eliminates defects caused by outgas. According to one aspect of the present embodiment, a wavelength division multiplexing filter that prevents the occurrence of defects that may be caused by outgas in a wavelength division multiplexing filter is provided.

Description

Optical device for wavelength division multiplexing that eliminates defects caused by outgas

The present invention relates to an optical device for wavelength division multiplexing, and more particularly, to an optical device for wavelength division multiplexing using a film to prevent the occurrence of defects due to outgas.

The content described in this section merely provides background information for the present embodiment and does not constitute the prior art.

Wavelength division multiplexing (WDM), or wavelength division multiplexing, is a technology that uses different wavelengths of laser light to apply multiple carrier signals to a single optical fiber. Since a plurality of signals can be simultaneously transmitted to a single optical fiber, wavelength division multiplexing has an advantage in that data communication capacity can be increased in proportion to the number of wavelengths used.

In order to receive each of a plurality of signals within a single optical fiber, an optical device for discriminating a plurality of wavelengths used is essential. As for the optical device for wavelength division multiplexing, a filter type wavelength division multiplexing optical device (hereinafter referred to as a 'wavelength division multiplexing filter') and an arrayed waveguide grating (AWG) are typically used.

In recent 5G communication, large-capacity wireless signals are transmitted and received by converting them into wired ones at the base station. In this process, a plurality of large-capacity wireless signals are simultaneously transmitted using wavelength division multiplexing technology. In 5G communication, for various reasons, a wavelength division multiplexing filter is used as an optical device for discriminating a plurality of wavelengths rather than an array type optical waveguide grating.

The wavelength division multiplexing filter includes optical elements bonded therein by using an adhesive such as epoxy during the manufacturing process. Outgas is generated in the process of curing the adhesive, and the outgas remains inside the wavelength division multiplexing filter. The internal outgas has a problem of causing defects in the wavelength division multiplexing filter over time.

It is an object of the present invention to provide a wavelength division multiplexing filter that prevents the occurrence of defects that may be caused by outgas in the wavelength division multiplexing filter.

According to an aspect of the present invention, a first optical fiber receiving a first optical signal having a plurality of wavelengths and a second optical fiber receiving a second optical signal having a wavelength band remaining from the first optical signal except for a preset wavelength band A filter that passes light of a preset wavelength band among the dual fiber fixing member fixing the light and incident light, but reflects the light of the remaining wavelength band in the direction of the second optical fiber and the light output from the dual fiber fixing member, A first lens coupled to a filter and incident light reflected from the filter into the second optical fiber, a first bonding unit bonding the filter and the first lens to fix the first lens, the first bonding unit, and the filter; A first film disposed between the first lens to close a gap formed between the filter and the first lens, and a second lens disposed physically apart from the filter and focusing the light passing through the filter a third optical fiber receiving the light focused by the second lens; a single fiber fixing member fixing the third optical fiber; a second bonding unit fixing the second lens and the single fiber fixing member by bonding; Wavelength division comprising: two bonding units; and a second film disposed between the second lens and the single-fiber fixing member to close a gap formed between the second lens and the single-fiber fixing member; Provides a multiplexing filter.

According to one aspect of the present invention, the first film and the second film is characterized in that as the adhesive portion is applied to one surface, respectively, to close the formed gap.

As described above, according to one aspect of the present invention, it is possible to prevent the occurrence of defects due to outgas in the wavelength division multiplexing filter, thereby minimizing defects.

1 and 2 are diagrams illustrating an operation principle of dividing a plurality of wavelengths using a wavelength division multiplexing filter.

3 is a cross-sectional view showing the configuration of a conventional wavelength division multiplexing filter.

4 is an enlarged view showing a configuration of a conventional wavelength division multiplexing filter.

5 is a diagram illustrating an optical path in a conventional wavelength division multiplexing filter.

6 is a view of an optical fiber core in a conventional wavelength division multiplexing filter.

7 is a cross-sectional view illustrating the configuration of a wavelength division multiplexing filter according to an embodiment of the present invention.

8 and 9 are cross-sectional views illustrating the configuration of a wavelength division multiplexing filter according to another embodiment of the present invention.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

Terms such as first, second, A, and B may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when a certain element is referred to as being “directly connected” or “directly connected” to another element, it should be understood that no other element is present in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. It should be understood that terms such as “comprise” or “have” in the present application do not preclude the possibility of addition or existence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification in advance. .

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, each configuration, process, process or method included in each embodiment of the present invention may be shared within a range that does not technically contradict each other.

1 and 2 are diagrams illustrating an operation principle of classifying a plurality of wavelengths using a wavelength division multiplexing filter.

Referring to FIG. 1 , if there are 7 wavelength division multiplexing filters capable of separating different wavelengths, 8 wavelengths may be separated.

Referring to FIG. 2 , optical signals of a plurality of wavelengths are applied to the first optical fiber 21 by a wavelength division multiplexing filter. The applied optical signal passes through the first lens 23 and the thin film filter 24 , the light of a preset wavelength is outputted through the thin film filter 24 , and the light of the remaining wavelength is filtered by the thin film filter 24 . and reflected to the second optical fiber 26 .

The dual fiber fixing member 22 arranges and fixes the first optical fiber 21 and the second optical fiber 26 .

The wavelength division multiplexing filter includes an optical element such as a dual fiber fixing member 22 , a first lens 23 , and a thin film filter 24 . In the conventional wavelength division multiplexing filter, each optical element is arranged at a predetermined distance, and each optical element is fixed to each other by an adhesive 25 such as epoxy.

3 to 5 are cross-sectional views of a conventional wavelength division multiplexing filter 100 .

Referring to FIG. 3 , an optical signal is applied to the first optical fiber 110 in the conventional wavelength division multiplexing filter 100 . The applied optical signal passes through the first lens 130 and the filter 140, and the light of a preset wavelength passes through the filter 140 and is output to the third optical fiber 118, and the light of the remaining wavelength passes through the filter ( It is filtered in 140 and reflected to the second optical fiber 114 .

The dual fiber fixing member 120 is fixed by disposing the first optical fiber 110 and the second optical fiber 114 therein.

The first lens 130 couples the light output from the dual fiber fixing member 120 to the filter 140 , and transmits the filtered light reflected from the filter 140 to the second optical fiber in the dual fiber fixing member 120 . It is made incident by focusing at (114). A GRIN lens may be used as the first lens 130 , and the GRIN lens serves to create parallel light or focused light. When the first lens 130 couples the light output from the dual fiber fixing member 120 to the filter 140 , the first lens 130 makes the light parallel light, and in the opposite direction makes the focused light.

The filter 140 passes only light of a preset wavelength band among the incident lights in the direction of the third optical fiber 118 , and reflects the light of the remaining wavelength band in the direction of the second optical fiber 114 . By means of the filter 140, only light of a desired wavelength band is passed, and the transmitting and receiving sides can communicate smoothly. As the filter 140 , a thin-film chip filter may be used.

The second lens 150 is disposed physically apart from the filter 140 , and focuses the light passing through the filter 140 . The second lens 150 is positioned on the side of the third optical fiber 118 so that the light passing through the filter 140 is completely incident on the third optical fiber 118 positioned on the single-fiber fixing member 160 . The second lens 150 may be a collimating lens, and performs a function of focusing parallel light. That is, the second lens 150 focuses the parallel light passing through the filter 140 to the third optical fiber 118 .

The housing 170 is a configuration disposed at the outermost part of the wavelength division multiplexing filter 100, and physically protects the internal configuration of the wavelength division multiplexing filter 100 from external force and prevents the optical axis from being distorted by the external force.

The first bonding unit 180 is fixed by bonding the dual fiber fixing member 120 and the first lens 130 after forming the air gap 191 by a predetermined interval. A bonding material such as epoxy is injected between the dual fiber fixing member 120 and the first lens 130 , and the bonding material is cured to complete the first bonding unit 180 .

The second bonding unit 182 bonds and fixes the first lens 130 and the filter 140 like the first bonding unit 180 .

The third bonding unit 184 bonds and fixes the second lens 150 and the single fiber fixing member 160 like the first bonding unit 180 .

The fourth bonding unit 186 bonds and fixes the housing 170 and the first and third

optical fibers

110 and 114 .

The fifth bonding unit 188 bonds and fixes the housing 170 and the first and third optical fibers 118 .

An air gap portion 190 is formed in the first bonding portion 180 to the third bonding portion 184 during the bonding process. Since the air gap portion 190 has a refractive index of 1, the air gap portion 190 at a predetermined interval is essential for coupling light to the first lens 130 and the third optical fiber 118 in the single fiber fixing member 160 . to be.

The light output from the first optical fiber 110 spreads from the end of the dual fiber fixing member 120 by a predetermined angle (usually corresponding to the numerical aperture), and is transmitted from the first lens 130 by the air gap part 190. The width is wide enough to make it into parallel light. The beam width of the collimated light generated by the first lens 130 must ensure that the filter 140 can fully perform the wavelength division multiplexing function (crossstock, loss, wavelength division degree, etc.). That is, the beam width of the light is changed enough to allow the first lens 130 to create a completely parallel light by the air gap part 190 so that the filter 140 can perform a complete function.

The air gap portion 190 formed by the third bonding portion 184 must have a predetermined width so that the light focused by the second lens 150 can be completely coupled to the third optical fiber 118 . That is, the width of the air gap portion 190 formed by the third bonding portion 184 is the focal point of the second lens 150 considering the width of the core (the portion where light is coupled) to the third optical fiber 118 . become a distance

Referring to FIG. 4 , the bonding material used in the first to third bonding portions is typically an epoxy, which is a cationic light curing agent having a positive cation. Epoxy is applied to the area to be bonded and cured by light.

Epoxy releases outgas of up to 0.1% of the total epoxy used in proportion to the amount of surface used. In particular, when the epoxy is thermally cured in the post-process, volatile condensed materials, unreacted photoinitiators, or saturated water vapor in the first to third bonding portions are released as outgas and are trapped in the air gap portion 190 . The outgas is condensed at room temperature, and a kind of vaporized material 191 containing moisture and Radical is generated.

Radicals of the vaporized material 191 react with the

lights

121 and 122 to become hydrophilic, and are gradually collected in the optical fiber core. In particular, when the light 121 and 122 having a light intensity distribution of a Gaussian profile is used because of the property of converging to a place where the intensity of light is strong, the vaporized material is more likely to be gathered to the center of the optical fiber. The vaporized material 191 collected in the optical fiber core is photocured again by the

lights

121 and 122 , and the photocured vaporized material 192 causes an effect that foreign substances are inserted into the air gap portion 190 .

As shown in FIG. 5 , in particular, when the light 121 and 122 having the light intensity distribution of the Gaussian profile is used, the photocured foreign material 192 has a hemispherical shape and functions like a convex lens. Due to the photocured foreign material functioning as a convex lens, the aforementioned air gap part 190 cannot guarantee the focal length and the beam width extension distance. This problem causes a defect that increases the crosstalk value of the optical device for wavelength division multiplexing.

6 is a view illustrating a defect in which a photocured foreign material is concentrated on an optical fiber core. It can be seen that most foreign substances are concentrated on the optical fiber core. As such, foreign substances concentrated on the optical fiber core interfere with securing the focal length and the beam width extension distance of the air gap portion 190, thereby causing defects.

Referring to FIG. 7 , the wavelength division multiplexing filter 100 according to an embodiment of the present invention includes a first optical fiber 110 , a second optical fiber 114 , a third optical fiber 118 , and a dual fiber fixing member 120 . , a first lens 130 , a filter 140 , a second lens 150 , a single fiber fixing member 160 , a housing 170 , bonding units 180 to 188 , and a gap filling unit 195 . .

The gap filling part 195 is disposed in close contact between the dual fiber fixing part 120 and the first lens 130 and between the second lens 150 and the single fiber fixing member 160 , respectively. The gap filling part 195 is implemented with a component or composition having a refractive index of 1 or close to 1, such as epoxy, gel, or micro lens. Accordingly, the gap filling part 195 disposed between the dual fiber fixing part 120 and the first lens 130 (hereinafter referred to as a 'first gap filling part') is an air gap part ( 190), it is possible to secure an appropriate focal length and a fixed beam width of the light irradiated from the first optical fiber 110 .

At the same time, since the first gap filling part 195 is disposed between the two

components

120 and 130 , both

components

120 and 130 are bonded (cured, etc.) by the first bonding unit 180 . It is possible to physically prevent the generation of the vaporized

substances

191 and 192 in the air or the concentration of the vaporized

substances

191 and 192 into the core of the first optical fiber 110 . This is also the same for the gap filling part 195 (hereinafter, referred to as a 'second gap filling part') disposed between the second lens 150 and the single fiber fixing member 160 . Since the second gap filling part 195 is also disposed between both

components

150 and 160, vaporized material ( It is possible to physically prevent the occurrence of foreign substances 192 around the core of the third optical fiber 118 due to the occurrence of 191 ) or the generated vaporized material 191 .

8 and 9 , the wavelength division multiplexing filter 100 according to an embodiment of the present invention includes a first optical fiber 110 , a second optical fiber 114 , a third optical fiber 118 , and a dual fiber fixing member ( 120), the first lens 130, the filter 140, the second lens 150, the single fiber fixing member 160, the housing 170, the bonding parts 180 to 188, the adhesive part 810 and the film ( 820).

The film 820 is disposed to seal (block) the air gap portion 190 from the outside, thereby sealing (blocking) the air gap portion 190 . Gas is generated while the bonding units 180 to 188 are bonded. The film 820 is disposed in both components (a fixing member and the first lens in FIG. 8) between which the air gap part 190 is positioned to seal the air gap part 190, thereby preventing the inflow of gas. The inflow of gas is prevented by the film 820, and the generation of vaporized material causing a change in the optical path is prevented.

Here, the film 820 may be implemented with a component similar to an optical fiber. For example, the film 820 may be implemented with Teflon or glass fiber. As the film 820 is implemented with a component similar to that of an optical fiber, it has a coefficient of thermal expansion or contraction similar to that of an optical fiber (glass material). Accordingly, even if the optical fiber thermally expands or contracts according to the temperature change and the distance between the air gap portions 190 is changed, the film 820 also expands or contracts with it and maintains the state disposed at both ends of the air gap portion 190 . can

An adhesive part 810 is applied to one end of the film 820 so that the film 820 can be disposed to block the air gap part 190 from the outside. As shown in FIG. 9, the film 820 surrounds the air gap portion 190 and is disposed to block the outside, and the portion 825 overlaps by a certain area between one end of the film 820 and the other end of the film 820. placed to exist. Accordingly, a surface facing the other surface of the film among the overlapping portions 825 in the film 820 is present. An adhesive portion 810 is applied to the above-described surface of the overlapping portions 825 (within one end) of the film 820 . Accordingly, when the film 820 is disposed as shown in FIG. 9 , the film 820 may be fixed in a corresponding shape by the adhesive part 810 and disposed.

At this time, when the film 820 is disposed, in order to prevent the air gap portion 190 from being completely sealed, the film 820 may be disposed as follows.

As one method, the film 820 may be implemented to be twice the length of the circumference of both components in which the air gap portion is located, so that it may be applied twice or more around the air gap portion. As such, when the film 820 is applied a plurality of times around the air gap portion, the air gap portion 190 may be completely sealed.

Alternatively, the film 820 has a property of being contracted when heat is applied, and may be implemented as long as the circumference of both components in which the air gap part is located. After the film 820 is applied around the air gap portion, heat may be applied to the film 820 . In this case, the film 820 may be contracted by heat and completely seal the air gap.

The adhesive part 810 may be implemented with a component having thermal conductivity (eg, Thermal Epoxy, etc.). Accordingly, all portions of the film 820 are thermally expanded or contracted.

After the film 820 is disposed, the bonding unit 180 is bonded to the outside of the film 820 (a direction away from the optical fiber). Accordingly, the film 820 may fundamentally block the vaporized material generated during the bonding process of the bonding unit from flowing into the air gap unit.

8 and 9 show that the film 820 is disposed in the air gap portion 190 where the bonding portion 180 is located, but the present invention is not limited thereto.

The above description is merely illustrative of the technical idea of this embodiment, and a person skilled in the art to which this embodiment belongs may make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present embodiment.

This patent is the result of research conducted with support from the Small and Medium Business Technology Information Promotion Agency with funding from the Korean government (Ministry of SMEs and Startups) in 2020. Development of high-reliability low-loss optical multiplexer for networks).

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on U.S. Patent Act 119( If priority is claimed under section a) (35 U.S.C § 119(a)), all contents thereof are incorporated herein by reference. In addition, if this patent application claims priority for countries other than the United States for the same reason as above, all contents thereof are incorporated into this patent application by reference.

Claims

a dual fiber fixing member for fixing a first optical fiber to which a first optical signal having a plurality of wavelengths is applied and a second optical signal to which a second optical signal having a wavelength band remaining from the first optical signal except for a preset wavelength band;

a filter that passes light of a preset wavelength band among the incident lights and reflects light of the remaining wavelength band in the direction of the second optical fiber;

a first lens coupling the light output from the dual-fiber fixing member to the filter and injecting the light reflected from the filter into the second optical fiber;

a first gap filling part disposed in close contact between the filter and the first lens;

a first bonding unit for bonding and fixing the filter and the first lens;

a second lens disposed physically apart from the filter and focusing the light passing through the filter;

a third optical fiber receiving the light focused by the second lens;

a single fiber fixing member for fixing the third optical fiber;

a second gap filling part disposed in close contact between the second lens and the single fiber fixing member; and

A first bonding unit for bonding and fixing the second lens and the single fiber fixing member

Wavelength division multiplexing filter comprising a.
According to claim 1,

The first gap filling part and the second gap filling part,

A wavelength division multiplexing filter, characterized in that it is implemented with a material having a refractive index of 1 or a material within a preset error range from 1.
a dual fiber fixing member for fixing a first optical fiber to which a first optical signal having a plurality of wavelengths is applied and a second optical signal to which a second optical signal having a wavelength band remaining from the first optical signal except for a preset wavelength band;

a filter that passes light of a preset wavelength band among the incident lights and reflects light of the remaining wavelength band in the direction of the second optical fiber;

a first lens coupling the light output from the dual-fiber fixing member to the filter and injecting the light reflected from the filter into the second optical fiber;

a first bonding unit for bonding and fixing the filter and the first lens;

a first film disposed between the first bonding unit and the filter and the first lens to seal a gap formed between the filter and the first lens;

a second lens disposed physically apart from the filter and focusing the light passing through the filter;

a third optical fiber receiving the light focused by the second lens;

a single fiber fixing member for fixing the third optical fiber;

a second bonding unit for bonding and fixing the second lens and the single fiber fixing member; and

a second film disposed between the second bonding unit and the second lens and the single-fiber fixing member to close a gap formed between the second lens and the single-fiber fixing member

Wavelength division multiplexing filter comprising a.
4. The method of claim 3,

The first film and the second film,

A wavelength division multiplexing filter, characterized in that the gap is closed by applying an adhesive portion on one surface of each.