TWI852525B - Anti-reflection film structure of infrared waveband and optical element - Google Patents

Abstract

An anti-reflection film structure of an infrared waveband can be disposed on a substrate of an optical element and includes a plurality of film layers that is composed of low refraction layers and high refraction layers, and the low and high refraction layers are stacked on the substrate alternately along the normal of the substrate. In the anti-reflection coating structure, the thickness of the layer closest to the substrate is larger than the thickness of the layer furthest from the substrate. The anti-reflection coating structure is penetrable by the light in an IR waveband of 950 nm~1650 nm.

Description

Anti-reflection film structure and optical element in infrared light band

The present invention relates to an anti-reflection film, in particular to an anti-reflection film structure and an optical element in the infrared light band.

With the advancement of technology, the requirements for electronic devices using optical components are becoming more diverse and stringent, such as but not limited to thin size, multiple functions, etc. Therefore, optical films are usually set on optical components. For example, anti-reflection films only allow light of a specific wavelength to pass through and reflect light of the remaining wavelengths.

However, the existing anti-reflection film allows light to pass through a narrow wavelength band, resulting in limited applications of the anti-reflection film.

Therefore, the purpose of the present invention is to provide an anti-reflection film structure and an optical element in the infrared light band, so as to overcome the problem that the anti-reflection film in the prior art allows light to pass through a narrow band width and a low transmittance, resulting in a small application range.

The present invention provides an anti-reflection film structure for infrared light band according to an embodiment, which is suitable for being arranged on a substrate of an optical element and comprises a plurality of film layers, wherein the plurality of film layers are composed of a plurality of low-refractive layers and a plurality of high-refractive layers, and the plurality of low-refractive layers and the plurality of high-refractive layers are alternately stacked on the substrate along the normal of the substrate, and light in the infrared light band of 950 nm to 1650 nm can pass through the anti-reflection film structure.

Optionally, the thickness of the film layer closest to the substrate in the anti-reflection film structure is smaller than the thickness of the film layer farthest from the substrate.

Optionally, the thickness of the low refractive layer farthest from the substrate is greater than the thickness of the high refractive layer closest to the substrate.

Optionally, the film layer with the smallest thickness in the anti-reflection film structure is the high refractive layer closest to the substrate.

Optionally, the film layer closest to the substrate in the anti-reflection film structure is the high refractive layer.

Optionally, the film layer farthest from the substrate in the anti-reflection film structure is the low-refractive layer.

Optionally, the number of the plurality of low-refractive layers is the same as the number of the plurality of high-refractive layers.

Optionally, a thickness ratio of the low refractive layer to the high refractive layer is 0.25-64.65.

Optionally, the plurality of film layers are divided into a plurality of film layer groups, each of the film layer groups is composed of one of the low refractive layers and one of the high refractive layers, the low refractive layer in each of the film layer groups is farther from the substrate than the high refractive layer, and the thickness ratio of the low refractive layer to the high refractive layer in each of the film layer groups is 0.25-37.42.

Optionally, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one the low-refractive layer and one the high-refractive layer, the low-refractive layer in each of the film layer groups is farther away from the substrate than the high-refractive layer, and the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group farthest from the substrate is smaller than the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group closest to the substrate.

Optionally, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one low-refractive layer and one high-refractive layer, the low-refractive layer in each of the film layer groups is farther away from the substrate than the high-refractive layer, and the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group that is second closest to the substrate among the multiple film layer groups is the largest.

Optionally, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one low-refractive layer and one high-refractive layer, the low-refractive layer in each of the film layer groups is farther away from the substrate than the high-refractive layer, and the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group that is second farthest from the substrate among the multiple film layer groups is the smallest.

Optionally, the absorption coefficient of the high refractive layer at a wavelength of 950 nm is 1.79e-4, and the absorption coefficient of the high refractive layer at a wavelength of 1650 nm is 4.7e-7.

Optionally, the material of the low refractive layer is silicon dioxide, and the material of the high refractive layer is hydrogen-doped silicon.

Optionally, the plurality of film layers include, in order along a direction away from the substrate: a first high refractive layer having a thickness of 7.74 nm; a first low refractive layer having a thickness of 115.73 nm; a second high refractive layer having a thickness of 13.37 nm; a second low refractive layer having a thickness of 500.37 nm; a third high refractive layer having a thickness of 30.67 nm; a third high refractive layer having a thickness of 30.67 nm; a fourth high refractive layer having a thickness of 122.13 nm; a fourth low refractive layer having a thickness of 31.09 nm; a fifth high refractive layer having a thickness of 47.07 nm; and a fifth low refractive layer having a thickness of 218.25 nm.

In addition, the present invention also provides an optical element according to an embodiment, which includes: a substrate; and the above-mentioned anti-reflection film structure, which is arranged on the substrate.

Optionally, the substrate is a sapphire substrate.

1 and 2, the anti-reflection film structure 20 provided by the present invention according to one embodiment is suitable for being disposed on a substrate surface 11 of a substrate 10 of an optical element 1. The substrate 10 is, for example but not limited to, a sapphire substrate. In other embodiments, the substrate may also be changed to a glass substrate.

The anti-reflection film structure 20 includes 10 film layers, which are composed of 5 low-refractive layers and 5 high-refractive layers. The refractive index of the high-refractive layer is higher than the refractive index of the low-refractive layer. The 5 low-refractive layers and the 5 high-refractive layers are alternately stacked on the substrate surface 11 along the normal N of the substrate 10. The anti-reflection film structure 20 allows light in the infrared light band of 950 nm to 1650 nm to pass through. In the anti-reflection film structure 20, the thickness ratio of the low-refractive layer to the high-refractive layer is 0.25 to 64.65.

The 10 film layers can be divided into 5 film layer groups, each of which is composed of a low refractive layer and a high refractive layer, and in each film layer group, the low refractive layer is farther from the substrate 10 than the high refractive layer. In each film layer group, the thickness ratio of the low refractive layer to the high refractive layer is 0.25~37.42. The material of the low refractive layer is silicon dioxide (SiO ₂ ), and the material of the high refractive layer is hydrogen-doped silicon (hereinafter referred to as Si-H). The absorption coefficient of the high refractive layer at a wavelength of 950 nm is 1.79e-4, and the absorption coefficient of the high refractive layer at a wavelength of 1650 nm is 4.7e-7.

As shown in Table 1, the 10 film layers are arranged in order along the direction away from the substrate 10: a first high refractive layer 21H, a first low refractive layer 21L, a second high refractive layer 22H, a second low refractive layer 22L, a third high refractive layer 23H, a third low refractive layer 23L, a fourth high refractive layer 24H, a fourth low refractive layer 24L, a fifth high refractive layer 25H and a fifth low refractive layer 25L.

Table 1 Film layer group# Membrane layer Material Thickness(nm) 1 First high refractive layer Si-H 7.74 First low refractive layer SiO ₂ 115.73 2 Second highest refractive layer Si-H 13.37 Second low refractive layer SiO ₂ 500.37 3 The third highest refractive layer Si-H 30.67 The third low refractive layer SiO ₂ 60.28 4 The fourth highest refractive layer Si-H 122.13 Fourth low refractive layer SiO ₂ 31.09 5 Fifth Highest Refractive Layer Si-H 47.07 Fifth low refractive layer SiO ₂ 218.25

It can be seen from Table 1 that the thickness of the first high refractive layer 21H closest to the substrate 10 is less than the thickness of the fifth low refractive layer 25L farthest from the substrate 10; the film layer with the smallest thickness in the anti-reflection film structure 20 is the first high refractive layer 21H; the thickness ratio of the low refractive layer to the high refractive layer of the fifth film layer group farthest from the substrate 10 is less than the thickness ratio of the low refractive layer to the high refractive layer of the first film layer group closest to the substrate 10; the thickness ratio of the low refractive layer to the high refractive layer of the second film layer group second closest to the substrate 10 is the largest; and the thickness ratio of the low refractive layer to the high refractive layer of the fourth film layer group second farthest from the substrate 10 is the smallest.

The following is a transmittance simulation test of the anti-reflection film structure 20 in Table 1. The anti-reflection film structure 20 is placed in an atmospheric environment and then irradiated from above (i.e., above the figure) with a reference wavelength of 550 nm, and the test result shown in the spectrum curve C in FIG. 2 is obtained.

In FIG2 , the transmittance of spectrum curve C in the infrared light band of 950 nm to 1650 nm is as high as over 99%. That is, light in this infrared light band can pass through the anti-reflection film structure 20, but light in the band below 950 nm and light in the band above 1650 nm will be blocked.

In summary, the anti-reflection film structure provided by the present invention can work in a wider infrared light band (950 nm~1650 nm), so it can be widely used in high-precision sapphire substrate processing or high-precision high-refractive index glass processing, thereby expanding the application range of optical components with the anti-reflection film structure of the present invention, and is suitable for almost any product that needs to penetrate the band of 950 nm~1650 nm, such as but not limited to applications in optical communication bands such as vehicle-mounted radars and infrared sensors.

Although the present invention is disclosed as above with the aforementioned embodiments, these embodiments are not intended to limit the present invention. Within the spirit and scope of the present invention, the changes, modifications and combinations of various embodiments are all within the scope of patent protection of the present invention. For the scope of protection defined by the present invention, please refer to the attached patent application scope.

1: Optical element 10: Substrate 11: Substrate surface 20: Anti-reflection film structure 21H: First high refractive layer 21L: First low refractive layer 22H: Second high refractive layer 22L: Second low refractive layer 23H: Third high refractive layer 23L: Third low refractive layer 24H: Fourth high refractive layer 24L: Fourth low refractive layer 25H: Fifth high refractive layer 25L: Fifth low refractive layer C: Spectral curve N: Normal line

After studying the detailed description in conjunction with the following figures, other aspects of the present invention and its advantages will be discovered: FIG. 1 is a schematic diagram of an optical element having an anti-reflection film structure of an embodiment of the present invention; and FIG. 2 is a spectrum curve diagram of the anti-reflection film structure of the optical element of FIG. 1 undergoing a transmittance test.

1:Optical components

10: Substrate

11: Substrate surface

20: Anti-reflective film structure

21H: First high refractive layer

21L: First low refractive layer

22H: The second highest refractive layer

22L: Second lowest refractive layer

23H: The third highest refractive layer

23L: The third lowest refractive layer

24H: The fourth highest refractive layer

24L: Fourth low refractive layer

25H: The fifth highest refractive layer

25L: The fifth lowest refractive layer

N: Normal

Claims (14)

An infrared light band anti-reflection film structure is suitable for being arranged on a substrate of an optical element and comprises a plurality of film layers, the plurality of film layers are composed of a plurality of low refractive layers and a plurality of high refractive layers, the plurality of low refractive layers and the plurality of high refractive layers are alternately stacked on the substrate along the normal of the substrate, the thickness of the film layer closest to the substrate in the anti-reflection film structure is less than the thickness of the film layer farthest from the substrate, the film layer with the smallest thickness in the anti-reflection film structure is the high refractive layer closest to the substrate, the material of the low refractive layer is silicon dioxide, the material of the high refractive layer is hydrogen-doped silicon, and light in the infrared light band of 950nm~1650nm can pass through the anti-reflection film structure. According to the anti-reflection film structure for infrared light bands described in claim 1, the thickness of the low refractive layer farthest from the substrate is greater than the thickness of the high refractive layer closest to the substrate. According to the anti-reflection film structure for infrared light bands as described in claim 1, the film layer closest to the substrate in the anti-reflection film structure is the high refractive layer. According to the anti-reflection film structure for infrared light bands as described in claim 1, the film layer farthest from the substrate in the anti-reflection film structure is the low refractive layer. According to the anti-reflection film structure for infrared light bands as described in claim 1, the number of the multiple low-refractive layers is the same as the number of the multiple high-refractive layers. According to the anti-reflection film structure for infrared light bands described in claim 1, the thickness ratio of the low refractive layer to the high refractive layer is 0.25~64.65. According to the anti-reflection film structure for infrared light bands described in claim 1, the plurality of film layers are divided into a plurality of film layer groups, each of the film layer groups is composed of one of the low refractive layers and one of the high refractive layers, the low refractive layer in each of the film layer groups is farther from the substrate than the high refractive layer, and the thickness ratio of the low refractive layer to the high refractive layer in each of the film layer groups is 0.25~37.42. According to the anti-reflection film structure for infrared light bands described in claim 1, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one low refractive layer and one high refractive layer, the low refractive layer in each film layer group is farther from the substrate than the high refractive layer, and the thickness ratio of the low refractive layer to the high refractive layer in the film layer group farthest from the substrate is smaller than the thickness ratio of the low refractive layer to the high refractive layer in the film layer group closest to the substrate. According to the anti-reflection film structure for infrared light bands described in claim 1, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one low-refractive layer and one high-refractive layer, the low-refractive layer in each of the film layer groups is farther from the substrate than the high-refractive layer, and the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group that is second closest to the substrate among the multiple film layer groups is the largest. According to the anti-reflection film structure for infrared light bands described in claim 1, the multiple film layers are divided into multiple film layer groups, each of the film layer groups is composed of one low-refractive layer and one high-refractive layer, the low-refractive layer in each of the film layer groups is farther from the substrate than the high-refractive layer, and the thickness ratio of the low-refractive layer to the high-refractive layer in the film layer group that is second farthest from the substrate among the multiple film layer groups is the smallest. According to the anti-reflection film structure in the infrared light band described in claim 1, the absorption coefficient of the high refractive layer at a wavelength of 950nm is 1.79e-4, and the absorption coefficient of the high refractive layer at a wavelength of 1650nm is 4.7e-7. According to the anti-reflection film structure of infrared light band described in claim 1, the multiple film layers include in order along the direction away from the substrate: a first high refractive layer with a thickness of 7.74nm; a first low refractive layer with a thickness of 115.73nm; a second high refractive layer with a thickness of 13.37nm; a second low refractive layer with a thickness of 500.37nm; a third high refractive layer with a thickness of 30.67nm; a third low refractive layer with a thickness of 60.28nm; a fourth high refractive layer with a thickness of 122.13nm; a fourth low refractive layer with a thickness of 31.09nm; a fifth high refractive layer with a thickness of 47.07nm; and a fifth low refractive layer with a thickness of 218.25nm. An optical element comprises: a substrate; and an anti-reflection film structure as described in any one of claims 1 to 12, disposed on the substrate. An optical element according to claim 13, wherein the substrate is a sapphire substrate.