JP2005004022A - Anti-reflection coating - Google Patents

Abstract

The present invention provides an antireflection film that optimizes optical characteristics of an optical component between two types of media.
In an antireflection film 2 in which a high refractive index material and a low refractive index material are alternately laminated on a base material 1 having an optical refractive index of 1.45 to 1.52, the first layer is made of a high refractive index material. The second layer is formed of a low refractive index material with an optical film thickness of 0.058 to 0.062λ with respect to the design center wavelength. The third layer is formed of a high refractive index material with an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength, and the fourth layer is formed of a low refractive index material with a thickness of 0.167 to the design center wavelength. An antireflection film formed to an optical film thickness of 0.177λ.
[Selection] Figure 1

Description

[0001]
[Industrial application fields]
The present invention relates to an antireflection film, and more particularly to an antireflection film that optimizes optical characteristics of an optical component between two types of media.
[0002]
[Prior art]
When light propagates through two media having different refractive indexes, part of the propagated light is reflected at the boundary surface between the two media. When one medium is air and the other medium is glass, about 4% of light is reflected at the interface between the air and glass.
In many cases, optical components are affected by this reflection loss or return light, and optimal optical characteristics cannot be obtained. Correspondingly, light reflection that occurs at the boundary surface between the light incident surface of the optical component and the incident side medium through which the incident light has propagated is prevented, or light from the optical component is prevented. In order to prevent light reflection occurring at the boundary surface between the outgoing exit surface and the outgoing side medium from which the outgoing light is going to propagate, an antireflection film called an AR coat is formed on these boundary surfaces. Is generally done.
By the way, in the conventional antireflection technology for light propagation, the antireflection film is generally formed corresponding to only one of the incident side medium and the output side medium of the optical component (Patent Document). 1).
[0003]
[Patent Document 1] Japanese Patent No. 2638806 Specification
[Problems to be solved by the invention]
However, as described above, the conventional antireflection technology in light propagation is designed and formed corresponding to only one of the incident side medium and the output side medium of the optical component. The antireflection condition is only satisfied between the part and one of the incident side medium and the output side medium. That is, only for one of the conditions in which light propagates through the incident side medium and enters the optical component, or in the one condition in which light exits from the optical component to the output side medium, the optical Only anti-reflective coatings that optimize the optical properties of the components are designed and formed.
[0005]
The present invention has the characteristics of an antireflection film that satisfies the air-to-air condition for an optical component, and the optical component or an optical component having a refractive index equivalent to that of the optical component has a reflection equivalent to that of the antireflection film. An antireflection film having the characteristics of an antireflection film that satisfies the conditions of the optical component is formed by forming an antireflection film and bringing the antireflection films of both optical components into contact with each other. That is, according to the present invention, an optical component to be prevented from being reflected and a multilayer antireflection film are formed on the optical surface by ion beam sputtering, so that two of them are face-to-air and facing each other. An antireflection film is provided that optimizes the optical characteristics of the optical component under butt contact with the optical component under conditions between the two types of media.
[0006]
[Means for Solving the Problems]
Claim 1 In an antireflection film 2 in which a high refractive index material and a low refractive index material are alternately laminated on a substrate 1 having an optical refractive index of 1.45 to 1.52, the first layer is made of a high refractive index material. The second layer is formed of a low refractive index material with an optical film thickness of 0.058 to 0.062λ with respect to the design center wavelength. The third layer is formed of a high refractive index material with an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength, and the fourth layer is formed of a low refractive index material with a thickness of 0.167 to the design center wavelength. An antireflection film formed with an optical film thickness of 0.177λ was constructed.
[0007]
And, in the antireflection film according to the second aspect of the present invention, an antireflection film having the base material as a single-mode optical fiber end face is formed.
According to a third aspect of the present invention, in the antireflection film according to the second aspect, two single mode optical fibers are prepared, an antireflection film of one single mode optical fiber, and an antireflection film of the other single mode optical fiber, An anti-reflection film that was in contact with each other was constructed.
[0008]
Here, the present invention provides a single mode optical fiber having an optical refractive index of 1.45 to 1.52 in which an antireflection film is formed by alternately forming a high refractive index material and a low refractive index material on the end face. Here, the first layer of the antireflection film is made of a high refractive index material with an optical film thickness of 0.038 to 0.140λ with respect to the design center wavelength, and the second layer is made of a low refractive index material. An optical film thickness of 0.058 to 0.062λ with respect to the design center wavelength is formed, and a third layer is formed of a high refractive index material with an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength. The fourth layer is made of a low refractive index material and has an optical film thickness of 0.167 to 0.177λ with respect to the design center wavelength, and the antireflection film of one single mode optical fiber and the other single mode light. Both single-mode optical fibers are brought into contact with the antireflection coating of the fiber. And forming the optical component assembly optically coupled to the other end of the light source or photodiodes.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the examples of the drawings.
The first embodiment will be described with reference to FIG. 1. An optical component 1 to be prevented from being reflected and an antireflection film 2 comprising a dielectric multilayer film formed on the optical surface thereof by ion beam sputtering. It consists of.
As the optical component 1 on which the antireflection film 2 is formed, a substrate having an optical refractive index of 1.45 to 1.52 is used. The antireflective film 2 is formed by alternately depositing the high refractive index material Ta ₂ O ₅ and the low refractive index material SiO ₂ on the optical component 1. Here, the first layer of the antireflection film 2 is made of a high refractive index material and has an optical film thickness of 0.038 to 0.140λ with respect to the design center wavelength, and the second layer is made of a low refractive index material and the design center wavelength. The third layer is formed of a high refractive index material and has an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength. The layer is made of a low refractive index material and has an optical film thickness of 0.167 to 0.177λ with respect to the design center wavelength. Here, the number of layers of the antireflection film 2 is four, but even if the number of layers is further increased, the effect of improving the optical characteristics of the optical component does not necessarily increase.
[0010]
Here, when the incident light 3 arrives at the optical component 1 through the antireflection film 2, the reflection of the light at the boundary surface between the optical component 1 and the air that is the incident medium is as shown in FIG. In the light transmission band of 1150 to 1450 nm of the antireflection film 2, it almost disappears.
Even when the outgoing light 4 is emitted and propagated from the optical component 1 through the antireflection film 2 to the air, the light is reflected at the interface between the optical component 1 and the air as the outgoing medium, as in the case of the incident light. Is almost gone. If the film thicknesses of all four layers of the antireflection film are changed within the above-described range, optical characteristics that change within a region defined by the uppermost curve and the lowermost curve in FIG. 2 can be obtained. .
[0011]
The second embodiment will be described with reference to FIG. 3. The optical component 1 and the antireflection film 2 formed on the optical surface thereof are the optical component 1 and the antireflection film 2 themselves in the first embodiment. . The second example is further equivalent to the second optical component 1 ′ equivalent to the optical component 1 in the first example and the antireflection film 2 in the first example formed on the optical surface thereof. And a second antireflection film 2 ′. Then, the antireflection film 2 of the optical component 1 and the second antireflection film 2 ′ of the second optical component 1 ′ are brought into butt contact.
[0012]
Here, when the incident light 3 arrives at the optical component 1 from the second optical component 1 ′ via the second antireflection film 2 ′ and the antireflection film 2, the optical component 1 and the second medium that is the incident side medium. The reflection of light at the interface with the optical component 1 ′ is almost eliminated within the light transmission band of the second antireflection film 2 ′ and the antireflection film 2 as shown in FIG.
That is, in the case of the conventional antireflection film, the optical component 1 uses the incident side medium as air and the optical characteristics of the optical component 1 are optimized between them. When the second optical component 1 ′ is different from air, the antireflection characteristic cannot be obtained. However, in the second embodiment, the antireflection film 2 and the second antireflection film 2 ′ are interposed between the optical component 1 and the second optical component 1 ′, so that the optical component 1, air, The antireflection characteristic is maintained even in the relationship with the optical component 1 ′ which is a different incident side medium, and light reflection within the light transmission band of the antireflection film is almost eliminated. When the film thicknesses of all four layers of the antireflection film are changed within the above-described range, optical characteristics that change within a region limited by the uppermost curve and the lowermost curve in FIG. 4 can be obtained. .
[0013]
Even when the emitted light 4 is emitted and propagated from the optical component 1 through the antireflection film 2 and the second antireflection film 2 ′ to the second optical component 1 ′ that is an exit side medium different from air, the incident light 4 is incident. As in the case of the above, the reflection of light at the boundary surface between the optical component 1 and the second antireflection film 2 ′ that is the exit side medium is almost eliminated.
The third embodiment will be described with reference to FIG. 5. This corresponds to an example in which the optical component 1 in the first embodiment is a single mode optical fiber 6. The antireflection film 2 is formed on the end face of the single mode optical fiber 6 by the ion beam sputtering method under the above conditions.
[0014]
When the incident light 3 emitted from the light source 5 to the single mode optical fiber 6 is received by the photodiode 7, the reflection loss at the end face of the single mode optical fiber 6 is almost eliminated in the transmission wavelength band of the antireflection film 2.
A fourth embodiment will be described with reference to FIG. 6. This is an example in which the optical component 1 in the second embodiment is a single mode optical fiber 6 and the optical component 1 ′ is a single mode optical fiber 6 ′. Equivalent to. Then, the antireflection film 2 of one single mode optical fiber 6 and the antireflection film 2 ′ of the other single mode optical fiber 6 ′ are brought into contact with each other, and the other ends of both the single mode optical fibers 6 and 6 ′ are connected to the light source 5. Are optically coupled to the photodiode 7. In the case of the fourth embodiment as well, like the second embodiment of FIG. 3, there is almost no reflection loss at the interface between both single mode optical fibers.
[0015]
【The invention's effect】
As described above, the present invention comprises an optical component to be prevented from being reflected and an antireflection film comprising a dielectric multilayer film formed on the optical surface by the ion beam sputtering method under the conditions described above. In the wavelength band 850 to 1650 nm used in the field of optical communication technology, the optical component can be applied to the optical component under the condition of the air component by contacting the two in a face-to-face relationship. On the other hand, it is possible to provide an antireflection film that optimizes optical characteristics under conditions between two types of media.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment;
FIG. 2 is a graph showing the reflectance with respect to the light wavelength in the first embodiment.
FIG. 3 is a diagram illustrating a second embodiment.
FIG. 4 is a diagram showing the reflectance with respect to the light wavelength of the second embodiment.
FIG. 5 is a diagram for explaining a third embodiment;
FIG. 6 is a diagram for explaining a fourth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical component 1 '2nd optical component 2 Antireflection film 2' 2nd antireflection film 3 Incident light 4 Outgoing light 5 Light source 6 Single mode optical fiber 6 'Single mode optical fiber 7 Photodiode

Claims (4)

In an antireflection film in which a high refractive index material and a low refractive index material are alternately laminated on a substrate having an optical refractive index of 1.45 to 1.52,
The first layer is formed of a high refractive index material with an optical film thickness of 0.038 to 0.140λ with respect to the design center wavelength,
The second layer is formed of a low refractive index material with an optical film thickness of 0.058 to 0.062λ with respect to the design center wavelength,
The third layer is formed of a high refractive index material with an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength,
The fourth layer is formed of a low refractive index material with an optical film thickness of 0.167 to 0.177λ with respect to the design center wavelength.
An antireflection film characterized by that. The antireflection film according to claim 1,
An antireflection film characterized in that the base material is a single-mode optical fiber end face. The antireflection film according to claim 2,
An antireflection film prepared by preparing two single mode optical fibers and contacting the antireflection film of one single mode optical fiber with the antireflection film of the other single mode optical fiber. Two single-mode optical fibers having an optical refractive index of 1.45 to 1.52 in which an antireflection film is formed by alternately forming a high refractive index material and a low refractive index material on an end face are prepared,
Here, the antireflection film has a first layer made of a high refractive index material with an optical film thickness of 0.038 to 0.140λ with respect to the design center wavelength, and a second layer made of a low refractive index material to the design center wavelength. On the other hand, an optical film thickness of 0.058 to 0.062λ is formed, and a third layer is formed of a high refractive index material to an optical film thickness of 0.129 to 0.137λ with respect to the design center wavelength. Is formed with an optical film thickness of 0.167 to 0.177λ with respect to the design center wavelength with a low refractive index material,
The antireflection film of one single mode optical fiber and the antireflection film of the other single mode optical fiber are brought into butt contact with each other,
An optical component assembly in which the other ends of both single-mode optical fibers are optically coupled to a light source or a photodiode.

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