Metal grating polaroid

Abstract

The utility model provides a metal grating polaroid which comprises a substrate, a first metal grating layer, a medium grating layer and a second metal grating layer. The first metal grating layer is arranged on the upper side of the substrate, the dielectric grating layer is arranged on the upper side of the first metal grating layer, and the second metal grating layer is arranged on the upper side of the dielectric grating layer; the dielectric grating layer is used for performing plasma resonance with the first metal grating layer and the second metal grating layer. According to the metal grating polaroid provided by the utility model, through the plasma resonance effect, the extinction ratio of the polaroid is greatly increased on the basis of keeping high average transmission efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of polarizing plates, in particular to a metal grating polarizing plate. Background Art

[0002] U.S. Patent US7158302 discloses a double metal layer polarizer, which has uneven transmission effect in the entire visible band. In the wavelength range of 500-700nm, the transmission efficiency of TM light is mostly above 70%, but at a wavelength of 400nm, the transmission efficiency of TM light is 63%, resulting in a low average transmission efficiency of TM light. Chinese patent CN1363048A discloses a broadband wire grid polarizer for the visible light band. By setting a region with a refractive index lower than the refractive index of the substrate between the metal grating and the substrate, the visible wavelength band where no resonance effect occurs is expanded, thereby providing a single-layer metal grating polarizer suitable for the visible light spectrum. Chinese patent 201210419189.9 proposes a polarizer that improves the transmission efficiency of TM light (>78%). However, the above polarizer cannot maintain a high extinction ratio while maintaining a high average transmission efficiency. Therefore, it is very necessary to design a metal grating polarizer. Utility Model Content

[0003] The utility model aims to provide a metal grating polarizer, which can significantly increase the extinction ratio on the basis of maintaining high average transmission efficiency through the plasma resonance effect between the first metal grating layer and the second metal dielectric grating layer.

[0004] To achieve the above purpose, the utility model provides the following solutions:

[0005] A metal grating polarizer comprises: a substrate, a first metal grating layer, a dielectric grating layer and a second metal grating layer; the first metal grating layer is arranged on the upper side of the substrate, the dielectric grating layer is arranged on the upper side of the first metal grating layer, and the second metal grating layer is arranged on the upper side of the dielectric grating layer; the dielectric grating layer is used to perform plasma resonance with the first metal grating layer and the second metal grating layer respectively.

[0006] Optionally, the periods of the first metal grating layer, the dielectric grating layer and the second metal grating layer are the same, and the ridge widths of the first metal grating layer, the dielectric grating layer and the second metal grating layer are the same.

[0007] Optionally, the duty ratios of the first metal grating layer, the dielectric grating layer and the second metal grating layer are all less than 0.5.

[0008] Optionally, the substrate and the dielectric grating layer are made of transparent flexible material or glass.

[0009] Optionally, the first metal grating layer and the second metal grating layer are both made of aluminum.

[0010] Optionally, the thickness of the first metal grating layer and the second metal grating layer are both 30 nm to 70 nm.

[0011] Optionally, the height of the first metal grating layer is 60 nm, the height of the second metal grating layer is 60 nm, and the height of the dielectric grating layer is 30 nm.

[0012] Optionally, the grating period ranges of the first metal grating layer and the second metal grating layer are both less than or equal to 200 nm.

[0013] According to the specific embodiments provided by the utility model, the utility model discloses the following technical effects: a metal grating polarizer, comprising: a substrate, a first metal grating layer, a dielectric grating layer and a second metal grating layer; a plurality of the first metal grating layers are arranged on the upper side of the substrate, a plurality of the dielectric grating layers are arranged on the upper side of the first metal grating layer, a plurality of the second metal grating layers are arranged on the upper side of the dielectric grating layer, and the dielectric grating layers are used to perform plasma resonance with the first metal grating layer and the second metal grating layer respectively; through the plasma resonance, the polarizer significantly increases the extinction ratio while maintaining a high average transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 This is a schematic structural diagram of a metal grating polarizer according to an embodiment of the utility model;

[0016] Figure 2a This is a graph showing the relationship between the transmission efficiency and wavelength of TM light in an embodiment of the present utility model;

[0017] Figure 2b A graph showing the relationship between the extinction ratio and the wavelength of an embodiment of the utility model;

[0018] Figure 3a This is a graph showing the relationship between the transmission efficiency of TM light and the wavelength and incident angle of the embodiment of the present utility model;

[0019] Figure 3b A graph showing the relationship between the extinction ratio, wavelength and incident angle of an embodiment of the present utility model;

[0020] Figure 4a This is a graph showing the relationship between the transmission efficiency of TM light and the wavelength and duty ratio of the embodiment of the present utility model;

[0021] Figure 4b A graph showing the relationship between the extinction ratio, wavelength and duty cycle of an embodiment of the utility model;

[0022] Figure 5a This is a graph showing the relationship between the transmission efficiency of TM light and the wavelength and the height of the dielectric grating layer in the embodiment of the present utility model;

[0023] Figure 5b This is a graph showing the relationship between the extinction ratio, wavelength, and dielectric grating layer height according to an embodiment of the present utility model.

[0024] Figure numerals: 1, substrate; 2, first metal grating layer; 3, dielectric grating layer; 4, second metal grating layer. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] The utility model aims to provide a metal grating polarizer, which can significantly increase the extinction ratio of the polarizer while maintaining a high average transmission efficiency through plasma resonance.

[0027] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] First, we need to give a definition of the transmission extinction ratio, which refers to the ratio of the transmission efficiency of TM polarized light to the transmission efficiency of TE polarized light. In the following description, the transmission efficiency of TM light is defined as Ttm, the transmission efficiency of TE light is defined as Tte, and the transmission extinction ratio Text = 10lg (Ttm / Tte).

[0029] In the present invention, since the focus is on improving the average transmission efficiency and extinction ratio in the visible band, the preferred range of the grating period p is p≤200nm, the duty ratio F<0.5, the thickness of the two metal grating layers is between 30nm and 70nm, and the substrate 1 and the dielectric grating layer 3 are transparent flexible materials or glass. If it is for the long-wave band, such as the infrared band, the parameters such as the grating period, duty ratio, metal layer thickness and dielectric layer thickness can be optimized under the premise that the structural model remains unchanged.

[0030] like Figure 1 As shown, the utility model provides a metal grating polarizer, comprising: a substrate 1, a first metal grating layer 2, a dielectric grating layer 3 and a second metal grating layer 4; a plurality of the first metal grating layers 2 are arranged on the upper side of the substrate 1, the dielectric grating layer 3 is arranged on the upper side of the first metal grating layer 2, and the second metal grating layer 4 is arranged on the upper side of the dielectric grating layer 3; the dielectric grating layer 3 is used to perform plasma resonance with the first metal grating layer 2 and the second metal grating layer 4 respectively.

[0031] The periods p of the first metal grating layer 2 , the dielectric grating layer 3 and the second metal grating layer 4 are the same, and the ridge widths w of the first metal grating layer 2 , the dielectric grating layer 3 and the second metal grating layer 4 are the same.

[0032] The duty ratios of the first metal grating layer 2 , the dielectric grating layer 3 and the second metal grating layer 4 (duty ratio F=w / p) are all less than 0.5.

[0033] The substrate 1 and the dielectric grating layer 3 are made of transparent flexible material or glass.

[0034] The thickness of the first metal grating layer 2 and the second metal grating layer 4 are both 30 nm to 70 nm.

[0035] The grating period ranges of the first metal grating layer 2 and the second metal grating layer 4 are both less than or equal to 200 nm.

[0036] If it is aimed at long-wave bands, such as the infrared band, parameters such as grating period, duty ratio, metal layer thickness, and dielectric layer thickness can be optimized without changing the structural model.

[0037] The utility model provides an embodiment: the incident light is visible light with a wavelength of 400nm-700nm, the substrate 1 is glass with a refractive index of 1.48, the first metal grating layer 2 is aluminum, the dielectric grating layer 3 is MgF2 with a refractive index of 1.38, and the second metal grating layer 4 is aluminum. The height h1 of the first metal grating layer 2 is 60nm, the height h2 of the dielectric grating layer 3 is 30nm, the height h3 of the second metal grating layer 4 is 60nm, and the width ratio F is 0.4.

[0038] The relationships between the transmission efficiency and extinction ratio of TM light obtained in this embodiment and the wavelength are as follows: Figure 2a and Figure 2b As shown, the transmission efficiency of TM light in the entire visible light band is greater than 82%, and the extinction ratio is greater than 33dB, indicating that the structure significantly increases the extinction ratio while maintaining a high average transmission efficiency.

[0039] Based on the parameter conditions of this embodiment, the influence of the change of the incident angle on the transmission efficiency and extinction ratio of the TM light is studied. The incident angle of the incident light varies in the range of 0 to 60 degrees, and the relationship between the transmission efficiency and extinction ratio of the TM light and the wavelength and the incident angle is as follows: Figure 3a and Figure 3b As shown, when the incident angle of the incident light varies in the range of 0 to 60 degrees, the transmission efficiency of TM light in the entire visible light band is greater than 82%, and the transmission extinction ratio is greater than 33dB, indicating that the utility model has high average transmission efficiency and high extinction ratio in a wide band and wide angle range.

[0040] Based on the parameters of this embodiment, the influence of the duty ratio change on the transmission efficiency and extinction ratio of TM light is studied, wherein F varies in the range of 0.3 to 0.7, and the other parameters are the same as those of the embodiment. Figure 4a and Figure 4b As shown, with the increase of F, the transmission efficiency of TM light gradually decreases and the extinction ratio gradually increases. When F=0.4, the transmission efficiency of TM light is greater than 82% and the extinction ratio is greater than 33dB.

[0041] Based on the parameters of this embodiment, the influence of the height change of the dielectric grating layer 3 on the transmission efficiency and extinction ratio of the TM light is studied. Among them, h2 varies in the range of 0 to 60 nm, and the other parameters are the same as those in the embodiment. Figure 5a As shown, when h2=0nm, that is, when there is no dielectric grating layer 3, the average transmission efficiency of the structure in the entire visible light band is about 90%; after the introduction of the dielectric grating layer 3, the transmission efficiency of TM light in the short-wave band (400nm~500nm) is reduced, and the transmission efficiency in the long-wave band (500nm~700nm) is improved. When h2=20nm and 40nm, the average transmission efficiency in the entire visible light band is still greater than 90%. When h2=60nm, the average transmission efficiency in the entire visible light band is less than 90%. As shown in FIG. Figure 5b As shown, when h2=0nm, that is, when there is no dielectric grating layer 3, the extinction ratio of the structure in the entire visible light band is greater than 30dB. After the introduction of the dielectric grating layer 3, the extinction ratio in the short-wave band (400nm-500nm) is slightly improved, and the extinction ratio in the long-wave band (500nm-700nm) is significantly improved. When h2=20nm and 40nm, the extinction ratio in the entire visible light band is greater than 33dB. It can be seen that by introducing the dielectric grating layer 3, the utility model can greatly improve the extinction ratio while ensuring that the average transmission efficiency remains unchanged.

[0042] The metal grating polarizer provided by the utility model comprises: a substrate, a first metal grating layer, a dielectric grating layer and a second metal grating layer; the first metal grating layer is arranged on the upper side of the substrate, the dielectric grating layer is arranged on the upper side of the first metal grating layer, and the second metal grating layer is arranged on the upper side of the dielectric grating layer; the dielectric grating layer is used to perform plasma resonance with the first metal grating layer and the second metal grating layer respectively. Through the plasma resonance, the polarizer greatly increases the extinction ratio while maintaining a high average transmission efficiency.

[0043] This article uses specific examples to illustrate the principles and implementation methods of the utility model. The above examples are only used to help understand the method and core ideas of the utility model. At the same time, for those skilled in the art, according to the ideas of the utility model, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the utility model.

Claims

1. A metal grating polarizer, characterized in that: include: A substrate, a first metal grating layer, a dielectric grating layer and a second metal grating layer; the first metal grating layer is arranged on the upper side of the substrate, the dielectric grating layer is arranged on the upper side of the first metal grating layer, and the second metal grating layer is arranged on the upper side of the dielectric grating layer; the dielectric grating layer is used to perform plasma resonance with the first metal grating layer and the second metal grating layer respectively.

2. The metal grating polarizer according to claim 1, characterized in that: The periods of the first metal grating layer, the dielectric grating layer and the second metal grating layer are the same, and the ridge widths of the first metal grating layer, the dielectric grating layer and the second metal grating layer are the same.

3. The metal grating polarizer according to claim 1, characterized in that: The duty ratios of the first metal grating layer, the dielectric grating layer and the second metal grating layer are all less than 0.

5.

4. The metal grating polarizer according to claim 1, characterized in that: The substrate and the dielectric grating layer are made of transparent flexible material or glass.

5. The metal grating polarizer according to claim 1, characterized in that: The first metal grating layer and the second metal grating layer are both made of aluminum.

6. The metal grating polarizer according to claim 1, characterized in that: The thickness of the first metal grating layer and the second metal grating layer are both 30nm-70nm.

7. The metal grating polarizer according to claim 1, characterized in that: The grating period ranges of the first metal grating layer and the second metal grating layer are both less than or equal to 200 nm.

Images