Polarizing spectroscopic filter, polarizing spectroscopic filter array, and polarizing spectroscopic sensor

Abstract

To provide a polarization spectral filter, a polarization spectral filter array, and a polarization spectral sensor.SOLUTION: A polarization spectral filter can selectively transmit light with a particular wavelength band with a particular ray polarizing component. The polarization spectral filter 100 includes a first reflector 110 and a second reflector 130 that are arranged to face each other in a first direction, and a lattice layer 120 disposed between the first reflector 110 and the second reflector 130. The lattice layer 120 includes a number of first lattice elements 120a and a number of second lattice elements 120b that are arranged alternately along a second direction perpendicular to the first direction. Each of the first lattice elements 120a is formed of a first dielectric material with a first refractive index. Each of the second lattice elements 120b is formed of a second dielectric material with a second refractive index that is higher than the first refractive index.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarization spectroscopic filter, a polarization spectroscopic filter array, and a polarization spectroscopic sensor, and more particularly to a polarization spectroscopic filter, a polarization spectroscopic filter array, and a polarization spectroscopic sensor that can simultaneously obtain polarization information and spectral information of incident light by using the polarization spectroscopic filter array, which can selectively transmit light of a specific wavelength band having a specific linear polarization component. [Background technology]

[0002] Spectroscopes are used to take ground photographs from drones, satellites, and aircraft to analyze agricultural field conditions, mineral distribution, surface vegetation, and pollution levels, and are also used in a variety of fields such as food safety, skin / face analysis, authentication, and biometric analysis. Recently, the application of spectroscopy has expanded to areas such as mobile healthcare.

[0003] Here, the polarized image can provide additional information such as pressure, surface defects, scratches, etc. in addition to general RGB information in fields such as industrial equipment and automotive electrical components, and the polarized image can also make it possible to more accurately identify objects in cloudy or foggy weather.

[0004] Therefore, the application fields of sensors capable of acquiring such spectral and polarized images are expanding. In addition, as image sensors are becoming smaller and their resolutions are increasing, research is ongoing to integrate such sensors into image sensors to acquire high-resolution spectral and polarized images. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2002 / 0080493 [Patent Document 2] US Patent Application Publication No. 2006 / 0262250 [Patent Document 3] U.S. Patent No. 9,052,454 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a polarizing spectral filter and a polarizing spectral filter array that can selectively transmit light in a specific wavelength band having a specific linearly polarized component.

[0007] The present invention also provides a polarization spectroscopic sensor that utilizes the polarization spectroscopic filter array and is capable of simultaneously obtaining polarization information and spectroscopic information of incident light. [Means for solving the problem]

[0008] A polarizing spectral filter according to one embodiment includes a first reflector, a second reflector arranged opposite the first reflector in a first direction, and a grating layer arranged between the first reflector and the second reflector, the grating layer including a number of first grating elements and a number of second grating elements arranged alternately along a second direction perpendicular to the first direction, each of the first grating elements being made of a first dielectric material having a first refractive index, and each of the second grating elements also being made of a second dielectric material having a second refractive index different from the first refractive index.

[0009] Each of the first lattice elements and each of the second lattice elements may have a rod shape, and the multiple first lattice elements and the multiple second lattice elements may be arranged in one dimension.

[0010] A first surface of each first grating element and a first surface of each second grating element may contact the first reflector, and a second surface of each first grating element opposite the first surface of each first grating element and a second surface of each second grating element opposite the first surface of each second grating element may contact the second reflector.

[0011] The thicknesses of each of the first grating elements and each of the second grating elements, the arrangement period of the multiple first grating elements and the multiple second grating elements, and the ratio of the first grating elements to the second grating elements can be determined so that the polarizing spectral filter transmits light in a first wavelength band among light having a first linear polarization component, and transmits light in a second wavelength band different from the first wavelength band among light having a second linear polarization component perpendicular to the first linear polarization component.

[0012] For example, the thickness of each first grating element and each second grating element is between 90 nm and 350 nm.

[0013] For example, the arrangement period of the multiple first grating elements and the multiple second grating elements is 150 nm to 300 nm.

[0014] For example, the ratio of the number of first grating elements to the number of second grating elements may be between 0.2 and 0.7.

[0015] The first and second dielectric materials are also transparent to light in a first band of wavelengths and light in a second band of wavelengths.

[0016] The polarizing spectral filter may further include a bandpass filter disposed on a surface of the first reflector, the bandpass filter blocking light in a first wavelength band and transmitting light in a second wavelength band.

[0017] The polarizing spectral filter may further include a quarter wave plate disposed on a surface of the first reflector.

[0018] The first reflector includes a number of first dielectric layers and a number of second dielectric layers alternately stacked along a third direction, and the second reflector includes a number of third dielectric layers and a number of fourth dielectric layers alternately stacked along the third direction, each of the first dielectric layers and each of the second dielectric layers being made of a dielectric material having a refractive index different from each other, and each of the third dielectric layers and each of the fourth dielectric layers also being made of a dielectric material having a refractive index different from each other.

[0019] A first dielectric layer of the first reflector and a third dielectric layer of the second reflector are made of the first dielectric material, and a second dielectric layer of the first reflector and a fourth dielectric layer of the second reflector are also made of the second dielectric material.

[0020] The grating layer may further include a number of third grating elements made of a third dielectric material having a third refractive index different from the first refractive index and the second refractive index, and the number of first grating elements, the number of second grating elements, and the number of third grating elements may be alternately arranged along a second direction perpendicular to the first direction.

[0021] According to another embodiment, a polarization spectral filter array includes a number of unit filter arrays arranged two-dimensionally, each unit filter array including a first polarization spectral filter set that transmits light of a first wavelength band and a second polarization spectral filter set that transmits light of a second wavelength band different from the first wavelength band, the first polarization spectral filter set including a first polarization spectral filter configured to transmit light having a first linear polarization component of the light of the first wavelength band and a second polarization spectral filter configured to transmit light having a second linear polarization component perpendicular to the first linear polarization component of the light of the first wavelength band, and the second polarization spectral filter set including a first polarization spectral filter configured to transmit light having the first linear polarization component of the light of the second wavelength band. the first polarizing spectral filter includes a third polarizing spectral filter configured to transmit light having a second linear polarization component out of light in a second wavelength band, and a fourth polarizing spectral filter configured to transmit light having a second linear polarization component out of light in a second wavelength band, each of the first polarizing spectral filter to the fourth polarizing spectral filter includes a first reflector and a second reflector arranged opposite to each other in a first direction, and a grating layer arranged between the first reflector and the second reflector, the grating layer including a number of first grating elements and a number of second grating elements alternately arranged along a second direction perpendicular to the first direction, each of the first grating elements being made of a first dielectric material having a first refractive index, and each of the second grating elements also being made of a second dielectric material having a second refractive index different from the first refractive index.

[0022] The multiple first grating elements and the multiple second grating elements of the grating layer of the second polarizing spectral filter are rotated by 90° in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the first polarizing spectral filter, and the multiple first grating elements and the multiple second grating elements of the grating layer of the fourth polarizing spectral filter are also rotated by 90° in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the third polarizing spectral filter.

[0023] Each of the first lattice elements and each of the second lattice elements may have a rod shape, and the multiple first lattice elements and the multiple second lattice elements may be arranged in one dimension.

[0024] For each of the first polarizing spectral filter to the fourth polarizing spectral filter, based on the thickness of each first grating element and each second grating element, the arrangement period of the multiple first grating elements and the multiple second grating elements, and the ratio of the first grating elements to the second grating elements, the first polarizing spectral filter is configured to transmit light of a first wavelength band out of light having a first linear polarization component, the second polarizing spectral filter is configured to transmit light of the first wavelength band out of light having a second linear polarization component, the third polarizing spectral filter is configured to transmit light of a second wavelength band out of light having the first linear polarization component, and the fourth polarizing spectral filter is also configured to transmit light of the second wavelength band out of light having the second linear polarization component.

[0025] The width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the first polarizing spectral filter are identical to the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the second polarizing spectral filter, and the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the third polarizing spectral filter are also identical to the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the fourth polarizing spectral filter.

[0026] Each of the first polarizing spectral filter through the fourth polarizing spectral filter may further include a bandpass filter disposed on a surface of the respective first reflector, transmitting light in a first wavelength band and a second wavelength band and blocking light in the remaining other wavelength bands.

[0027] The first polarizing spectral filter set may further include a fifth polarizing spectral filter configured to transmit light of a first wavelength band having a third linear polarization component rotated 45° with respect to the first linear polarization component, and the second polarizing spectral filter set may further include a sixth polarizing spectral filter configured to transmit light of a second wavelength band having a third linear polarization component rotated 45° with respect to the first linear polarization component, and the fifth polarizing spectral filter and the sixth polarizing spectral filter may each include the first reflector, the second reflector, and the grating layer.

[0028] The multiple first grating elements and the multiple second grating elements of the grating layer of the fifth polarizing spectral filter are rotated by 45° in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the first polarizing spectral filter, and the multiple first grating elements and the multiple second grating elements of the grating layer of the sixth polarizing spectral filter are also rotated by 45° in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the third polarizing spectral filter.

[0029] The first polarizing spectral filter set may further include a fifth polarizing spectral filter configured to transmit light having a first linear polarization component of light in a first wavelength band, and the second polarizing spectral filter set may further include a sixth polarizing spectral filter configured to transmit light having a first linear polarization component of light in a second wavelength band, and the fifth polarizing spectral filter and the sixth polarizing spectral filter may each include the first reflector, the second reflector, and the grating layer.

[0030] According to yet another embodiment, a polarization spectroscopic sensor includes the above-described polarization spectroscopic filter array and an image sensor including a plurality of two-dimensionally arranged sensing pixels that sense the intensity of light transmitted through the polarization spectroscopic filter array. [Brief description of the drawings]

[0031] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing a schematic configuration of a grating layer of the polarizing spectral filter shown in FIG. [Diagram 3] 2 is a graph showing an example of the transmission characteristic of the polarizing spectral filter shown in FIG. 1; [Figure 4] 2 is a graph showing an example of transmission characteristics of the polarization spectral filter shown in FIG. 1 according to the polarization angle of two different transmission wavelength bands. [Diagram 5] 2 is a graph showing an example of a change in the transmission characteristic of the polarizing spectral filter shown in FIG. 1; [Figure 6] FIG. 13 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to another embodiment. [Figure 7] FIG. 13 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to another embodiment. [Figure 8] 8 is a graph showing an example of the transmission characteristic of the polarizing spectral filter shown in FIG. 7. [Figure 9] FIG. 13 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to still another embodiment. [Figure 10] FIG. 13 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to still another embodiment. [Figure 11] FIG. 13 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to still another embodiment. [Figure 12] 1 is a perspective view showing a schematic configuration of a polarization spectroscopic filter array and a polarization spectroscopic sensor including the same according to an embodiment; [Figure 13] 13 is a diagram illustrating an example of the configuration of the polarization spectral filter array illustrated in FIG. 12. [Figure 14] 13 is a diagram showing an example of a polarization spectral filter arrangement in one polarization spectral filter group of each unit filter array of the polarization spectral filter array shown in FIG. 12. [Figure 15] 15 is a cross-sectional view taken along the line AA' in FIG. 14. [Figure 16] 13 is a diagram showing another example of a polarization spectral filter arrangement in one polarization spectral filter group of each unit filter array of the polarization spectral filter array shown in FIG. 12 . [Figure 17] 17 is a cross-sectional view taken along the line BB' in FIG. 16. [Figure 18] 17 is another cross-sectional view taken along the line BB' in FIG. 16. [Figure 19] 17 is yet another cross-sectional view taken along the line BB' in FIG. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, a polarization spectroscopic filter, a polarization spectroscopic filter array, and a polarization spectroscopic sensor will be described in detail with reference to the accompanying drawings. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of description. In addition, the embodiments described below are merely exemplary, and various modifications are possible from such embodiments.

[0033] In the following, the terms "upper" and "above" may include not only those directly above in contact, but also those above without contact. A singular expression includes a plural expression unless the context clearly indicates otherwise. In addition, when a part "includes" a certain component, it does not mean to exclude other components, but means that other components may be further included, unless otherwise specified to the contrary.

[0034] Use of the term "said" and similar referents can refer to both the singular and the plural. Unless a method step is expressly described in an order or otherwise stated to the contrary, such steps may be performed in any suitable order, but are not necessarily limited to the order described.

[0035] In addition, terms such as "unit" and "module" used in the specification refer to a unit that processes at least one function or operation, and may be realized by hardware or software, or a combination of hardware and software.

[0036] The line connections or connecting members between components illustrated in the drawings are illustrative of functional connections and / or physical or circuit connections, and in an actual device, various functional, physical, or circuit connections may be shown as alternative or additional functional connections, physical connections, or circuit connections.

[0037] The use of any examples or exemplary terms is merely for the purpose of illustrating in detail the technical ideas, and the scope is not limited by such examples or exemplary terms, except as limited by the claims.

[0038] 1 is a cross-sectional view illustrating a schematic configuration of a polarization spectral filter according to an embodiment. Referring to FIG. 1, a polarization spectral filter 100 according to an embodiment may include a first reflector 110, a grating layer 120 disposed on the first reflector 110, and a second reflector 130 disposed on the grating layer 120. Thus, the first reflector 110 and the second reflector 130 are disposed opposite each other along the thickness direction (i.e., the vertical direction of the polarization spectral filter 100), and the grating layer 120 is disposed between the first reflector 110 and the second reflector 130.

[0039] The first reflector 110 and the second reflector 130 are also distributed Bragg reflectors (DBRs) formed by repeatedly and alternately stacking two dielectric layers having different refractive indices. For example, the first reflector 110 may include a number of first dielectric layers 110a and a number of second dielectric layers 110b alternately stacked along the thickness direction. The second reflector 130 may include a number of third dielectric layers 130a and a number of fourth dielectric layers 130b alternately stacked along the thickness direction. Each of the first dielectric layers 110a and each of the second dielectric layers 110b are also made of a dielectric material having a different refractive index. Also, each of the third dielectric layers 130a and each of the fourth dielectric layers 130b are also made of a dielectric material having a different refractive index. For example, each first dielectric layer 110a includes a first dielectric material having a first refractive index, each second dielectric layer 110b includes a second dielectric material having a second refractive index different from the first refractive index, each third dielectric layer 130a includes a third dielectric material having a third refractive index, and each fourth dielectric layer 130b includes a fourth dielectric material having a fourth refractive index different from the third refractive index.

[0040] For example, the first dielectric layer 110a and the second dielectric layer 110b may be made of Si, TiO 2 , SiO 2 , Si 2 N 3 The third dielectric layer 130a and the fourth dielectric layer 130b are also made of two different dielectric materials selected from the group consisting of Si, TiO 2 , SiO2 , Si 2 N 3 For example, the first dielectric layer 110a is made of Si, TiO 2 , SiO 2 and Si 2 N 3 The second dielectric layer 110b includes a dielectric material selected from the group consisting of Si, TiO 2 , SiO 2 and Si 2 N 3 The first reflector 110 may include another dielectric material selected from the above. Also, the first dielectric layer 110a of the first reflector 110 and the third dielectric layer 130a of the second reflector 130 may be made of the same dielectric material, and the second dielectric layer 110b of the first reflector 110 and the fourth dielectric layer 130b of the second reflector 130 may be made of the same dielectric material. Alternatively, the first dielectric layer 110a of the first reflector 110 and the fourth dielectric layer 130b of the second reflector 130 may be made of the same dielectric material, and the second dielectric layer 110b of the first reflector 110 and the third dielectric layer 130a of the second reflector 130 may be made of the same dielectric material.

[0041] According to such a structure of the first reflector 110 and the second reflector 130, reflection occurs at the interface between the first dielectric layer 110a and the second dielectric layer 110b, which have mutually different refractive indices, and at the interface between the third dielectric layer 130a and the fourth dielectric layer 130b, which have mutually different refractive indices, but by matching the phases of all the reflected light, a high reflectance can be obtained. For this purpose, the optical thickness (i.e., the value obtained by multiplying the physical thickness by the refractive index of the layer material) of each of the first dielectric layer 110a to the fourth dielectric layer 130b can be selected to be roughly ¼ of the wavelength band of the light transmitted by the polarizing spectral filter 100.

[0042] The first reflector 110 and the second reflector 130 arranged opposite to each other form a cavity that resonates light. The lattice layer 120 is arranged in the cavity formed by the first reflector 110 and the second reflector 130. Light incident through the upper surface of the first reflector 110 can be emitted through the lower surface of the second reflector 130 while resonating between the first reflector 110 and the second reflector 130. The light repeatedly passes through the lattice layer 120 while resonating between the first reflector 110 and the second reflector 130. Therefore, the characteristics of the light emitted through the lower surface of the second reflector 130 can be mainly determined by the structure of the lattice layer 120.

[0043] In the disclosed embodiment, the grating layer 120 is also configured to have polarization-dependent properties. To that end, the grating layer 120 may include a number of first grating elements 120a and a number of second grating elements 120b arranged alternately along a horizontal direction perpendicular to the thickness direction. For example, the number of first grating elements 120a and the number of second grating elements 120b may be arranged such that the lower surfaces of the number of first grating elements 120a and the lower surfaces of the number of second grating elements 120b in the thickness direction are in contact with the first reflector 110 and are located on the same plane, and the upper surfaces of the number of first grating elements 120a and the upper surfaces of the number of second grating elements 120b in the thickness direction are in contact with the second reflector 130 and are located on the same plane.

[0044] The first grating element 120a and the second grating element 120b are also made of dielectric materials having different refractive indices. In other words, each of the first grating elements 120a is made of a first dielectric material having a first refractive index, and each of the second grating elements 120b is made of a second dielectric material having a second refractive index different from the first refractive index. For example, the first grating element 120a and the second grating element 120b are made of a material such as Si, TiO 2 , SiO 2 , Si 2 N 3In addition to the aforementioned materials, the first and second dielectric materials constituting the first and second grating elements 120a and 120b may include any other material transparent to light in the transmission wavelength band of the polarizing spectral filter 100.

[0045] Also, the first grating element 120a is made of the same dielectric material as the first dielectric layer 110a of the first reflector 110 and the third dielectric layer 130a of the second reflector 130, and the second grating element 120b is made of the same dielectric material as the second dielectric layer 110b of the first reflector 110 and the fourth dielectric layer 130b of the second reflector 130. Alternatively, the first grating element 120a may be made of the same dielectric material as the first dielectric layer 110a of the first reflector 110 and the fourth dielectric layer 130b of the second reflector 130, and the second grating element 120b may be made of the same dielectric material as the second dielectric layer 110b of the first reflector 110 and the third dielectric layer 130a of the second reflector 130.

[0046] FIG. 2 is a perspective view showing a schematic configuration of the grating layer 120 of the polarizing spectral filter 100 shown in FIG. 1. Referring to FIG. 2, each of the first grating elements 120a and each of the second grating elements 120b of the grating layer 120 may have a bar shape extending long in one direction. The first grating elements 120a and the second grating elements 120b are repeatedly and alternately arranged along the width direction. The first grating elements 120a and the second grating elements 120b have the same thickness T. The first grating elements 120a have the same width W1, and the second grating elements 120b have the same width W2. Therefore, the first grating elements 120a and the second grating elements 120b are arranged at a constant period P.

[0047] Since the multiple first grating elements 120a and the multiple second grating elements 120b are arranged one-dimensionally in the above-mentioned manner, the grating layer 120 and the polarizing spectral filter 100 can have polarization-dependent characteristics. For example, among the light resonating between the first reflector 110 and the second reflector 130, the transmittance of the polarizing spectral filter 100 for light having a polarization component parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b may differ from the transmittance of the polarizing spectral filter 100 for light having a polarization component perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b. In particular, the polarizing spectral filter 100 according to this embodiment may have a different transmission wavelength band depending on the polarization direction of the light.

[0048] For example, FIG. 3 is a graph showing an example of the transmission characteristic of the polarizing spectral filter 100 shown in FIG. 1. Referring to FIG. 3, the wavelength of light transmitted through the polarizing spectral filter 100 has peaks in two separated narrow wavelength bands. For example, the light transmitted through the polarizing spectral filter 100 may have a first spectrum SP1 having a central wavelength of about 825 nm and a second spectrum SP2 having a central wavelength of about 875 nm. The first spectrum SP1 and the second spectrum SP2 may have narrow wavelength widths. For example, the full width at half maximum (FWHM) of the first spectrum SP1 and the full width at half maximum of the second spectrum SP2 may range from about 1 nm to about 10 nm. Therefore, the first spectrum SP1 and the second spectrum SP2 are not overlapped with each other, and the transmittance of the polarizing spectral filter 100 is almost close to 0 in the wavelength band between the first spectrum SP1 and the second spectrum SP2. The half-width of the first spectrum SP1 and the half-width of the second spectrum SP2 become smaller as the number of pairs of the first dielectric layer 110a and the second dielectric layer 110b of the first reflector 110 and the number of pairs of the third dielectric layer 130a and the fourth dielectric layer 130b of the second reflector 130 increase.

[0049] In particular, the light of the first spectrum SP1 has a polarization component perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b of the grating layer 120, and the light of the second spectrum SP2 has a polarization direction parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b of the grating layer 120. Therefore, the polarizing spectral filter 100 has two different transmission wavelength bands having polarization directions perpendicular to each other. In other words, the polarizing spectral filter 100 has two different transmission wavelength bands, and the polarizing spectral filter 100 has polarization characteristics perpendicular to each other for the two transmission wavelength bands.

[0050] For example, FIG. 4 is a graph showing an example of the transmission characteristics of the polarization spectral filter 100 shown in FIG. 1 according to the polarization angle of two different transmission wavelength bands. Referring to FIG. 4, the light of the first spectrum SP1, which is parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b, has a transmittance of approximately 0 through the polarization spectral filter 100. The light of the first spectrum SP1, which is perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b, has a transmittance of approximately 0.9 through the polarization spectral filter 100. On the other hand, the light of the second spectrum SP2, which is perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b, has a transmittance of approximately 0 through the polarization spectral filter 100. The light of the second spectrum SP2, which is parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b, has a transmittance of approximately 0.9 through the polarization spectral filter 100.

[0051] The specific transmission wavelength band and polarization characteristics of the polarization spectral filter 100 can be determined by the thickness T of each of the first grating elements 120a and each of the second grating elements 120b, the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b, the ratio of the first grating elements 120a to the second grating elements 120b, etc. For example, the thickness T of each of the first grating elements 120a and each of the second grating elements 120b can range from about 90 nm to about 350 nm. Also, the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b can range from 150 nm to 300 nm.

[0052] Therefore, the size of each of the first grating elements 120a and each of the second grating elements 120b is smaller than the transmission wavelength of the polarization spectroscopic filter 100. For example, the thickness T of each of the first grating elements 120a and each of the second grating elements 120b is smaller than ½ or ⅓ of the transmission wavelength of the polarization spectroscopic filter 100. In addition, the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b is smaller than ½ or ⅓ of the transmission wavelength of the polarization spectroscopic filter 100.

[0053] Because the first grating element 120a and the second grating element 120b have the same thickness, the ratio of the first grating element 120a to the second grating element 120b is the same as the ratio of the width W1 of the first grating element 120a to the width W2 of the second grating element 120b. For example, if a first refractive index of a first dielectric material forming the first grating element 120a is lower than a second refractive index of a second dielectric material forming the second grating element 120b, the ratio of the first grating element 120a to the second grating element 120b (W1 / W2) can range from about 0.2 to about 0.7. The transmission characteristics of the polarizing spectral filter 100 can be adjusted simply by fixing the thickness T of the first grating elements 120a and the second grating elements 120b, and the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b, and adjusting the ratio (W1 / W2) of the first grating elements 120a to the second grating elements 120b.

[0054] For example, Fig. 5 is a graph showing an example of a change in the transmission characteristic of the polarizing spectral filter 100 shown in Fig. 1 according to a change in the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b in the grating layer 120. In Fig. 5, the graph marked "str1" shows a case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.7, the graph marked "str2" shows a case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.5, and the graph marked "str3" shows a case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.3. 5, the three peaks on the left side are polarized light components perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b of the grating layer 120, and the three peaks on the right side are polarized light components parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b of the grating layer 120. Referring to FIG 5, it can be seen that as the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b increases, the two transmission wavelength bands of the polarizing spectral filter 100 gradually shift toward the longer wavelength side.

[0055] Although the grating layer 120 has been described as including only the first grating element 120a and the second grating element 120b, the present invention is not necessarily limited thereto. The grating layer 120 may also be configured by alternately arranging three or more or four or more grating elements having different refractive indices. There is no particular limit to the number of grating elements arranged alternately in the grating layer 120.

[0056] For example, FIG. 6 is a cross-sectional view showing a schematic configuration of a polarization spectroscopic filter according to another embodiment. The polarization spectroscopic filter 200 shown in FIG. 6 is similar to the polarization spectroscopic filter 100 shown in FIG. 1, except that the grating layer 120 includes three grating elements. Referring to FIG. 6, the grating layer 120 may include a number of first grating elements 120a, a number of second grating elements 120b, and a number of third grating elements 120c arranged alternately. Each of the first grating elements 120a is made of a first dielectric material having a first refractive index, each of the second grating elements 120b is made of a second dielectric material having a second refractive index different from the first refractive index, and each of the third grating elements 120c is also made of a third dielectric material having a third refractive index different from the first and second refractive indexes. The number of first grating elements 120a, the number of second grating elements 120b, and the number of third grating elements 120c may be arranged one-dimensionally along a horizontal direction perpendicular to the thickness direction.

[0057] On the other hand, in the graphs of Fig. 3 and Fig. 5, the polarizing spectral filter 100 has two different transmission wavelength bands having polarization characteristics perpendicular to each other. Moreover, such two transmission wavelength bands are completely separated and do not overlap with each other. Therefore, by selecting only one of the two different transmission wavelength bands, the polarizing spectral filter 100 is configured to transmit only light having a specific polarization component among light in a specific transmission wavelength band. Alternatively, a method of selecting one transmission wavelength band in the polarizing spectral filter according to another embodiment will be described below.

[0058] FIG. 7 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to another embodiment. The polarization spectral filter 300 shown in FIG. 7 is similar to the polarization spectral filter 100 shown in FIG. 1, except that it further includes a band-pass filter 140 disposed on the upper surface of the second reflector 130. In other words, the band-pass filter 140 is disposed on the light-entering surface of the polarization spectral filter 300. Such a band-pass filter 140 is configured to transmit only one of the wavelength bands of the first spectrum SP1 and the second spectrum SP2 shown in FIG. 3, and to block the other wavelength bands. For example, the band-pass filter 140 is configured to block light in a wavelength range of 800 nm to 850 nm and to transmit light in a wavelength range of 850 nm to 900 nm. As a result, the polarizing spectral filter 300 is configured to transmit only light of the second spectrum SP2 having a polarization component parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b, and to block light of the first spectrum SP1 having a polarization component perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b.

[0059] Fig. 8 is a graph showing an example of the transmission characteristic of the polarizing spectral filter 300 shown in Fig. 7. In Fig. 8, the graph marked "str1" shows the case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.7, the graph marked "str2" shows the case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.5, and the graph marked "str3" shows the case where the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b is 0.3. Referring to FIG. 8, when the bandpass filter 140 is used, light having polarization components parallel to the longitudinal direction of the first grating element 120a and the second grating element 120b of the grating layer 120 passes through the polarization spectral filter 300, and the wavelength band of the light passing through the polarization spectral filter 300 can be adjusted according to the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b.

[0060] Alternatively, the bandpass filter 140 may be configured to transmit light in a wavelength range of, for example, 800 nm to 850 nm and block light in a wavelength range of 850 nm to 900 nm. In this case, the polarizing spectral filter 300 may transmit only light having a polarization component perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b. In addition, by adjusting the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b, the transmission wavelength band of light having a polarization component perpendicular to the longitudinal direction of the first grating element 120a and the second grating element 120b may be adjusted.

[0061] 9 is a cross-sectional view illustrating a schematic configuration of a polarization spectral filter according to another embodiment. Although the band-pass filter 140 is illustrated as being disposed on the upper surface of the second reflector 130 in FIG. 7, the position of the band-pass filter 140 is not necessarily limited thereto. The band-pass filter 140 may be disposed anywhere outside the cavity formed by the first reflector 110 and the second reflector 130. For example, referring to FIG. 9, the polarization spectral filter 400 may include the band-pass filter 140 disposed on the lower surface of the first reflector 110. In other words, the band-pass filter 140 is also disposed on the light output surface of the polarization spectral filter 400.

[0062] FIG. 10 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to another embodiment. Referring to FIG. 10, the polarization spectral filter 500 is similar to the polarization spectral filter 300 shown in FIG. 7, and may further include a quarter-wave plate 150 disposed between the band-pass filter 140 and the second reflector 130. The quarter-wave plate 150 serves to delay the phase of the incident light by about a quarter of the wavelength of the incident light. Such a quarter-wave plate 150 may also be formed by patterning a dielectric material having a relatively high refractive index into a nanoscale structure smaller than the wavelength of light. For example, the quarter-wave plate 150 may be formed of a material such as Si, TiO 2 or Si 2 N 3 The metasurface may also be formed by

[0063] When the phase of the incident light is delayed by the quarter wavelength plate 150 by about a quarter wavelength of the wavelength of the incident light, the linearly polarized light component of the incident light is changed to a circularly polarized light component, and the circularly polarized light component is changed to a linearly polarized light component. In other words, the quarter wavelength plate 150 can change linearly polarized light to circularly polarized light and circularly polarized light to linearly polarized light. For example, a first linearly polarized light component is changed by the quarter wavelength plate 150 to a first circularly polarized light component, and a second linearly polarized light component perpendicular to the first linearly polarized light component is changed by the quarter wavelength plate 150 to a second circularly polarized light component rotated in the opposite direction to the first circularly polarized light component. Therefore, by further disposing the quarter wavelength plate 150, light having a circularly polarized light component is transmitted through the polarizing spectral filter 500.

[0064] FIG. 11 is a cross-sectional view showing a schematic configuration of a polarization spectral filter according to another embodiment. Although FIG. 10 shows the quarter wave plate 150 disposed on the upper surface of the second reflector 130, the position of the quarter wave plate 150 is not necessarily limited thereto. Such a quarter wave plate 150 may be disposed anywhere outside the cavity formed by the first reflector 110 and the second reflector 130. For example, referring to FIG. 11, the polarization spectral filter 600 may include the quarter wave plate 150 disposed on the lower surface of the first reflector 110. In other words, the quarter wave plate 150 is also disposed on the light output surface of the polarization spectral filter 600.

[0065] 10 and 11, the positions of the quarter wave plate 150 and the bandpass filter 140 may be interchanged. For example, the bandpass filter 140 may be disposed on an upper surface of the second reflector 130, and the quarter wave plate 150 may be disposed on an upper surface of the bandpass filter 140. Alternatively, the bandpass filter 140 may be disposed on a lower surface of the first reflector 110, and the quarter wave plate 150 may be disposed on a lower surface of the bandpass filter 140.

[0066] In addition, the quarter-wave plate 150 and the band-pass filter 140 are also disposed on opposite sides to each other. For example, the quarter-wave plate 150 is disposed on the upper surface of the second reflector 130, and the band-pass filter 140 is also disposed on the lower surface of the first reflector 110. Alternatively, the band-pass filter 140 is disposed on the upper surface of the second reflector 130, and the quarter-wave plate 150 is also disposed on the lower surface of the first reflector 110.

[0067] The polarization spectral filter according to the above embodiment can selectively transmit light of a specific wavelength band having a specific linear polarization or circular polarization component without using a separate polarization filter and a separate spectral filter. In addition, the polarization spectral filter according to the above embodiment can be fabricated small enough to match the pixel size of an image sensor. Therefore, the polarization spectral filter array according to the above embodiment can be integrated with an image sensor to simultaneously obtain polarization information and spectral information. In addition, by integrating the polarization spectral filter array according to the above embodiment with an image sensor, it is possible to provide a miniaturized polarization spectral image sensor that can be mounted on a small mobile device such as a smartphone.

[0068] For example, Fig. 12 is a perspective view showing a schematic configuration of a polarization spectroscopic filter array and a polarization spectroscopic sensor including the same according to an embodiment. Referring to Fig. 12, a polarization spectroscopic sensor 1000 according to an embodiment may include an image sensor 1100 and a polarization spectroscopic filter array 1200 arranged on the image sensor 1100. The polarization spectroscopic filter array 1200 includes a number of unit filters UPF arranged in a two-dimensional array (e.g., arranged along rows and columns). 11 ,UPF 12 ,UPF 21 , .... The image sensor 1100 may also include a number of sensing pixels arranged two-dimensionally to convert the intensity of incident light into an electrical signal. Thus, the sensing pixels of the image sensor 1100 can sense the intensity of light transmitted through the polarizing and spectral filter array 1200.

[0069] 13 is an exemplary diagram showing the configuration of the polarization spectral filter array 1200 shown in FIG 12. Referring to FIG 13, the polarization spectral filter array 1200 includes a number of unit filters UPF arranged two-dimensionally. 11 ,UPF 12 ,UPF 21 , .... Each unit filter UPF of the polarization spectroscopic filter array 1200 11 ,UPF 12 ,UPF 21 , ... are configured to analyze a number of different polarization states associated with a number of different wavelengths of light. 11 ,UPF 12 ,UPF 21 , . . . are the minimum units of the polarization and spectral filter array 1200 for simultaneously obtaining both polarization information and spectral information related to the incident light.

[0070] Each unit filter UPF 11 ,UPF 12 ,UPF 21 , ... may include a number of polarization spectral filter sets WF that transmit light of different wavelengths. 11 ,UPF 12 ,UPF 21 , ... are illustrated as including 16 polarizing and spectral filter sets WF that transmit the first wavelength band light λ1 through the sixteenth wavelength band light λ16, respectively. However, each unit filter UPF 11 ,UPF 12 ,UPF 21 The number of polarization and spectral filter sets WF arranged within the unit filters UPF 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62 11 ,UPF 12 ,UPF 21 . . , a number of polarizing and spectroscopic filter sets WF are also arranged in the form of a two-dimensional array.

[0071] FIG. 14 illustrates each unit filter array UPF of the polarization spectroscopic filter array 1200 illustrated in FIG. 11 ,UPF 12 ,UPF 21 14 shows an example of a polarization spectral filter array in one of the polarization spectral filter assemblies WF. Referring to FIG. 14, each polarization spectral filter assemblies WF may include, for example, a first polarization spectral filter PF1 to a fourth polarization spectral filter PF4 arranged in a 2×2 array. The first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 are also configured to transmit light having linear polarization components in different directions. For example, the first polarization spectral filter PF1 is also configured to transmit light having a first linear polarization component. The second polarization spectral filter PF2 is also configured to transmit light having a second linear polarization component perpendicular to the first linear polarization component. The third polarization spectral filter PF3 is also configured to transmit light having a third linear polarization component tilted at 45° with respect to the first linear polarization component. In addition, the fourth polarization spectral filter PF4 is also configured to transmit light having a fourth linear polarization component tilted at 135° with respect to the first linear polarization component.

[0072] FIG. 15 is a cross-sectional view taken along the line A-A' in FIG. 14. FIG. 15 is a schematic diagram showing an example of a partial configuration of a polarization spectroscopic sensor 1000 including an array of polarization spectroscopic filters in one polarization spectroscopic filter set WF shown in FIG. 14 and an image sensor 1100 corresponding thereto. Referring to FIG. 15, each of the first polarization spectroscopic filter PF1 to the fourth polarization spectroscopic filter PF4 may have the same structure as the polarization spectroscopic filter 300 shown in FIG. 7. Although FIG. 15 shows only the first polarization spectroscopic filter PF1 and the third polarization spectroscopic filter PF3, the above-mentioned configuration is also applied to the first polarization spectroscopic filter PF1 to the fourth polarization spectroscopic filter PF4. In other words, the first polarization spectroscopic filter PF1 to the fourth polarization spectroscopic filter PF4 may include a first reflector 110, a grating layer 120, a second reflector 130, and a band-pass filter 140, respectively. In the first polarizing spectral filter PF1 to the fourth polarizing spectral filter PF4, the first reflector 110, the second reflector 130 and the band-pass filter 140 are integrally extended to form a common configuration.

[0073] In the first to fourth polarizing spectral filters PF1 to PF4, the multiple first grating elements 120a and second grating elements 120b of the grating layer 120 may be arranged along different directions so that the first to fourth polarizing spectral filters PF1 to PF4 can transmit light of different linear polarization components. For example, the first grating elements 120a and second grating elements 120b of the grating layer 120 of the second polarizing spectral filter PF2 may be arranged perpendicular to the first grating elements 120a and second grating elements 120b of the grating layer 120 of the first polarizing spectral filter PF1. In other words, the first grating elements 120a and second grating elements 120b of the grating layer 120 of the second polarizing spectral filter PF2 are rotated by 90° on the horizontal plane with respect to the first grating elements 120a and second grating elements 120b of the grating layer 120 of the first polarizing spectral filter PF1.

[0074] The first and second grating elements 120a and 120b of the third polarization spectral filter PF3 may be arranged to be inclined at 45° with respect to the first and second grating elements 120a and 120b of the first polarization spectral filter PF1. In other words, the first and second grating elements 120a and 120b of the grating layer 120 of the third polarization spectral filter PF3 are rotated at 45° on the horizontal plane with respect to the first and second grating elements 120a and 120b of the grating layer 120 of the first polarization spectral filter PF1. The first and second grating elements 120a and 120b of the fourth polarization spectral filter PF4 may be arranged to be inclined at 135° with respect to the first and second grating elements 120a and 120b of the first polarization spectral filter PF1. In other words, the first grating element 120a and the second grating element 120b of the grating layer 120 of the fourth polarizing spectral filter PF4 are rotated 135° in the horizontal plane relative to the first grating element 120a and the second grating element 120b of the grating layer 120 of the first polarizing spectral filter PF1.

[0075] The first to fourth polarization spectral filters PF1 to PF4 arranged in one uniform polarization spectral filter set WF are configured to transmit light of the same wavelength band. As described above, the transmission bands of the first to fourth polarization spectral filters PF1 to PF4 are also determined by the thickness T of the first grating element 120a and the second grating element 120b, the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b, and the ratio (W1 / W2) of the first grating element 120a to the second grating element 120b. Therefore, within one identical polarization spectral filter set WF, the thicknesses T of the first grating elements 120a and the second grating elements 120b of the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 are identical to each other, the arrangement periods P of the multiple first grating elements 120a and the multiple second grating elements 120b are identical to each other, and the ratios (W1 / W2) of the first grating elements 120a to the second grating elements 120b are also identical to each other.

[0076] Light transmitted through the first to fourth polarizing spectral filters PF1 to PF4 can be incident on different pixels of the image sensor 1100. To this end, the first to fourth polarizing spectral filters PF1 to PF4 are arranged in one-to-one correspondence with the pixels of the image sensor 1100. Thus, by analyzing electrical signals output from the pixels of the image sensor 1100 corresponding to the first to fourth polarizing spectral filters PF1 to PF4, respectively, it is possible to extract information on the light intensity of the first linear polarization component, the light intensity of the second linear polarization component, the light intensity of the third linear polarization component, and the light intensity of the fourth linear polarization component in the same wavelength band light.

[0077] All the polarization spectral filter sets WF may include the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 described above. The first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 arranged in different polarization spectral filter sets WF are configured to transmit different wavelength band light. For example, the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 in the polarization spectral filter set WF for analyzing the linear polarization component of the first wavelength band light λ1 are configured to transmit the first wavelength band light λ1, and the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 in the polarization spectral filter set WF for analyzing the linear polarization component of the second wavelength band light λ2 are configured to transmit the second wavelength band light λ2.

[0078] For convenience of the manufacturing process, the thickness T of all the first grating elements 120a and the second grating elements 120b in the polarization spectral filter array 1200 may be the same as one another. In this case, the transmission bands of the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 may be mainly determined by the arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b and the ratio (W1 / W2) of the first grating elements 120a to the second grating elements 120b. Therefore, the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 arranged in different polarization spectral filter sets WF may have different arrangement periods P of the first grating elements 120a and the multiple second grating elements 120b, or may have different ratios (W1 / W2) of the first grating elements 120a to the second grating elements 120b.

[0079] In one embodiment, the thickness T and arrangement period P of the multiple first grating elements 120a and the multiple second grating elements 120b are the same overall in the polarization spectral filter array 1200. In this case, the first polarization spectral filter PF1 to the fourth polarization spectral filter PF4 arranged in the different polarization spectral filter sets WF may differ from each other only in the ratio (W1 / W2) of the first grating elements 120a to the second grating elements 120b.

[0080] The transmission bands of the first polarizing spectral filter PF1 through the fourth polarizing spectral filter PF4 are also determined by the transmission band of the band-pass filter 140. The transmission bands of the band-pass filters 140 in different polarizing spectral filter sets WF may be different from each other. Alternatively, one common band-pass filter 140 may be used throughout the polarizing spectral filter array 1200. In that case, the band-pass filter 140 is configured to transmit the first wavelength band light λ1 through the sixteenth wavelength band light λ16 and block the remaining wavelength band light.

[0081] FIG. 16 illustrates each unit filter array UPF of the polarization spectroscopic filter array 1200 illustrated in FIG. 11 ,UPF 12 ,UPF21 16 shows another example of the polarization spectroscopic filter array in one polarization spectroscopic filter set WF of 16A, 16B, .... Also, Fig. 17 is an exemplary cross-sectional view taken along the line B-B' in Fig. 16. Fig. 17 shows a schematic diagram of an example of a partial configuration of a polarization spectroscopic sensor 1000 including an array of polarization spectroscopic filters in one polarization spectroscopic filter set WF shown in Fig. 16 and an image sensor 1100 corresponding thereto.

[0082] 16, each polarization spectral filter set WF may include, for example, a first polarization spectral filter PF1 through a sixth polarization spectral filter PF6 arranged in a 2 x 3 array. The first polarization spectral filter PF1 through the fourth polarization spectral filter PF4 are configured to transmit light having linear polarization components in different directions. The configurations and operations of the first polarization spectral filter PF1 through the fourth polarization spectral filter PF4 are the same as those already described with reference to FIG. 14, and therefore will not be described again.

[0083] The fifth polarizing spectral filter PF5 is configured to transmit light having a first circular polarization component, and the sixth polarizing spectral filter PF6 is configured to transmit light having a second circular polarization component rotated in the opposite direction to the first circular polarization component. To this end, the fifth polarizing spectral filter PF5 may further include a quarter-wave plate 150 disposed between the second reflector 130 and the band-pass filter 140, as shown in FIG. 17. Although not shown in FIG. 17, the sixth polarizing spectral filter PF6 may also further include a quarter-wave plate 150 disposed between the second reflector 130 and the band-pass filter 140. Thus, the configuration of the fifth polarizing spectral filter PF5 and the sixth polarizing spectral filter PF6 is the same as the configuration of the polarizing spectral filter 500 shown in FIG. 10.

[0084] The first grating element 120a and the second grating element 120b of the grating layer 120 of the fifth polarizing spectral filter PF5 may be arranged parallel to the first grating element 120a and the second grating element 120b of the grating layer 120 of the first polarizing spectral filter PF1. Meanwhile, the first grating element 120a and the second grating element 120b of the grating layer 120 of the sixth polarizing spectral filter PF6 may be arranged perpendicular to the first grating element 120a and the second grating element 120b of the grating layer 120 of the first polarizing spectral filter PF1. Therefore, the first grating element 120a and the second grating element 120b of the grating layer 120 of the sixth polarizing spectral filter PF6 are arranged parallel to the first grating element 120a and the second grating element 120b of the grating layer 120 of the second polarizing spectral filter PF2. As a result, the light transmitted through the fifth polarizing spectral filter PF5 and the light transmitted through the sixth polarizing spectral filter PF6 have circularly polarized light components rotated in opposite directions.

[0085] According to the embodiment illustrated in Figures 16 and 17, by analyzing the electrical signals output from the pixels corresponding to the first polarization spectral filter PF1 to the sixth polarization spectral filter PF6 of the image sensor 1100, information about the light intensities of various linear polarization components and circular polarization components of light in the same wavelength band can be extracted.

[0086] 17, the first to fourth polarizing spectral filters PF1 to PF4 may further include a spacer 160 disposed on the second reflector 130 to maintain a constant position of the bandpass filter 140 in the thickness direction. The thickness of the spacer 160 is also the same as the thickness of the quarter wave plate 150.

[0087] FIG. 18 is a cross-sectional view of another example taken along the line B-B' in FIG. 16. FIG. 18 is a schematic diagram of another example of a partial configuration of a polarization spectroscopic sensor 1000 including an array of polarization spectroscopic filters in one polarization spectroscopic filter set WF illustrated in FIG. 16 and an image sensor 1100 corresponding thereto. Referring to FIG. 18, the band-pass filter 140 is also disposed under the first reflector 110. In this case, the band-pass filter 140 is also disposed facing the image sensor 1100. In addition, in the fifth polarization spectroscopic filter PF5 and the sixth polarization spectroscopic filter PF6, the quarter-wave plate 150 is also disposed between the first reflector 110 and the band-pass filter 140. In the embodiment illustrated in FIG. 18, the quarter-wave plate 150 is embedded in the pass filter 140. Thereby, it is not necessary to use a separate spacer.

[0088] FIG. 19 is a cross-sectional view of yet another example taken along the line B-B' in FIG. 16. FIG. 19 is a schematic diagram of yet another example of a configuration of a polarization spectroscopic sensor 1000 including an array of polarization spectroscopic filters in one polarization spectroscopic filter set WF shown in FIG. 16 and an image sensor 1100 corresponding thereto. Referring to FIG. 19, the bandpass filter 140 is disposed on the upper surface of the second reflector 130, and the ¼ wave plate 150 is also disposed on the lower surface of the first reflector 110 in the fifth polarization spectroscopic filter PF5 and the sixth polarization spectroscopic filter PF6. In addition, a spacer 160 may be further disposed on the lower surface of the first reflector 110 of the first polarization spectroscopic filter PF1 to the fourth polarization spectroscopic filter PF4. The thickness of the spacer 160 is the same as the thickness of the ¼ wave plate 150.

[0089] The above-mentioned polarized light spectroscopy filter, polarized light spectroscopy filter array, and polarized light spectroscopy sensor have been described with reference to the embodiments shown in the drawings, but they are merely exemplary, and a person skilled in the art would understand that various modifications and other equivalent embodiments are possible therefrom. Therefore, the disclosed embodiments should be considered from an explanatory perspective, not a limiting perspective. The scope of the claims is set forth in the claims, not in the above description, and all differences within the scope of the claims should be interpreted as being within the scope of the claims. [Explanation of symbols]

[0090] 100,200,300,400,500,600,PF Polarizing Spectral Filter 110,130 reflector 110a, 110b, 130a, 130b Dielectric layers 120 lattice layer 120a,120b,120c lattice element 140 Bandpass Filter 150 1 / 4 wave plate 160 Spacer 1000 Polarimetric Spectroscopic Sensor 1100 Image Sensor 1200 Polarizing Spectral Filter Array UPF 11 ,UPF 12 ,UPF 21 Unit Filter Array WF Polarizing and spectral filter set

Claims

1. A first reflector; and a second reflector disposed opposite the first reflector in a first direction; a grating layer disposed between the first reflector and the second reflector; a quarter wave plate disposed on a surface of the first reflector; The grating layer includes a number of first grating elements and a number of second grating elements alternately arranged along a second direction perpendicular to the first direction, each first grating element is made of a first dielectric material having a first refractive index; each second grating element is made of a second dielectric material having a second refractive index different from the first refractive index; Each of the first lattice elements and each of the second lattice elements has a rod shape with a longitudinal direction perpendicular to the first direction and the second direction, and the multiple first lattice elements and the multiple second lattice elements are arranged in a one-dimensional manner, a thickness of each of the first grating elements and each of the second grating elements, an arrangement period of the multiple first grating elements and the multiple second grating elements, and a ratio of the first grating elements to the second grating elements are determined so as to transmit light of a first wavelength band among light having a first linearly polarized component perpendicular to the longitudinal direction, and to transmit light of a second wavelength band different from the first wavelength band among light having a second linearly polarized component parallel to the longitudinal direction, the quarter wave plate changes the first linear polarization component into a first circular polarization component and the second linear polarization component into a second circular polarization component rotated in an opposite direction relative to the first circular polarization component.

2. a first surface of each first grating element and a first surface of each second grating element contact the first reflector; 2. The polarizing spectral filter of claim 1, wherein a second surface of each first grating element opposing a first surface of each first grating element and a second surface of each second grating element opposing a first surface of each second grating element are in contact with the second reflector.

3. 2. The polarizing spectral filter of claim 1, wherein a thickness of each first grating element and each second grating element is between 90 nm and 350 nm.

4. 2. The polarizing spectral filter according to claim 1, wherein the arrangement period of the multiple first grating elements and the multiple second grating elements is 150 nm to 300 nm.

5. 2. The polarizing spectroscopic filter of claim 1, wherein the ratio of the number of first grating elements to the number of second grating elements is between 0.2 and 0.

7.

6. 2. The polarizing spectral filter of claim 1, wherein the first and second dielectric materials are transparent to light in a first wavelength band and light in a second wavelength band.

7. 10. The polarizing spectral filter of claim 1, further comprising a bandpass filter disposed on a surface of the first reflector, the bandpass filter blocking light in a first wavelength band and transmitting light in a second wavelength band.

8. the first reflector includes a plurality of first dielectric layers and a plurality of second dielectric layers alternately stacked along a third direction; the second reflector includes a number of third dielectric layers and a number of fourth dielectric layers alternately stacked along a third direction; each of the first dielectric layers and each of the second dielectric layers are made of a dielectric material having a different refractive index; 2. The polarizing spectral filter of claim 1, wherein each of the third dielectric layers and each of the fourth dielectric layers are made of dielectric materials having refractive indices different from each other.

9. 9. The polarizing spectral filter of claim 8, wherein a first dielectric layer of the first reflector and a third dielectric layer of the second reflector are made of the first dielectric material, and a second dielectric layer of the first reflector and a fourth dielectric layer of the second reflector are made of the second dielectric material.

10. the grating layer further includes a number of third grating elements made of a third dielectric material having a third refractive index different from the first and second refractive indices; The polarizing spectral filter of claim 1 , wherein the multiple first grating elements, the multiple second grating elements, and the multiple third grating elements are alternately arranged along a second direction perpendicular to the first direction.

11. A number of unit filter arrays arranged two-dimensionally, Each of the unit filter arrays includes a first polarizing and spectral filter set that transmits light in a first wavelength band, and a second polarizing and spectral filter set that transmits light in a second wavelength band different from the first wavelength band; the first polarization spectral filter set includes a first polarization spectral filter configured to transmit light having a first linear polarization component among light in a first wavelength band, and a second polarization spectral filter configured to transmit light having a second linear polarization component perpendicular to the first linear polarization component among light in the first wavelength band, the second polarization spectral filter set includes a third polarization spectral filter configured to transmit light having a first linear polarization component from among light in a second wavelength band, and a fourth polarization spectral filter configured to transmit light having a second linear polarization component from among light in the second wavelength band, The first polarizing spectral filter to the fourth polarizing spectral filter each include a first reflector and a second reflector disposed opposite each other in a first direction; a grating layer disposed between the first reflector and the second reflector; a quarter wave plate disposed on a surface of the first reflector; The grating layer includes a number of first grating elements and a number of second grating elements alternately arranged along a second direction perpendicular to the first direction, each first grating element is made of a first dielectric material having a first refractive index; each second grating element is made of a second dielectric material having a second refractive index different from the first refractive index; Each of the first lattice elements and each of the second lattice elements has a rod shape with a longitudinal direction perpendicular to the first direction and the second direction, and the multiple first lattice elements and the multiple second lattice elements are arranged in a one-dimensional manner, For each of the first polarization spectral filter to the fourth polarization spectral filter, based on the thickness of each of the first grating elements and each of the second grating elements, the arrangement period of the multiple first grating elements and the multiple second grating elements, and the ratio of the first grating elements to the second grating elements, the first polarizing spectral filter is configured to transmit light in a first wavelength band out of light having a first linearly polarized component perpendicular to the longitudinal direction; the second polarization spectral filter is configured to transmit light in the first wavelength band among light having a second linearly polarized component parallel to the longitudinal direction, the third polarization spectral filter is configured to transmit light in a second wavelength band out of the light having the first linear polarization component, the fourth polarization spectral filter is configured to transmit light in the second wavelength band out of the light having the second linear polarization component, the quarter wave plate includes a dielectric material patterned into nanoscale structures to change the first linear polarization component into a first circular polarization component and to change the second linear polarization component into a second circular polarization component that is rotated in an opposite direction relative to the first circular polarization component.

12. the multiple first grating elements and the multiple second grating elements of the grating layer of the second polarizing spectral filter are rotated by 90° on a plane perpendicular to a first direction with respect to the multiple first grating elements and the multiple second grating elements of the grating layer of the first polarizing spectral filter; 12. The polarizing spectral filter array of claim 11, wherein the multiple first grating elements and the multiple second grating elements of the grating layer of the fourth polarizing spectral filter are rotated 90 degrees in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the third polarizing spectral filter.

13. the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the first polarization spectral filter are the same as the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the second polarization spectral filter; 12. The polarizing spectral filter array of claim 11, wherein the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the third polarizing spectral filter are identical to the width and thickness of each of the first grating elements, the width and thickness of each of the second grating elements, and the ratio between the first and second grating elements of the fourth polarizing spectral filter.

14. 12. The polarizing spectral filter array of claim 11, wherein each of the first polarizing spectral filter to the fourth polarizing spectral filter further includes a bandpass filter disposed on a surface of the respective first reflector, the bandpass filter transmitting light of a first wavelength band and a second wavelength band and blocking light of the remaining other wavelength bands.

15. the first polarization spectral filter set further includes a fifth polarization spectral filter configured to transmit light having a third linear polarization component rotated 45° with respect to the first linear polarization component among light in the first wavelength band; the second polarization spectral filter set further includes a sixth polarization spectral filter configured to transmit light having a third linear polarization component rotated 45° with respect to the first linear polarization component among light in the second wavelength band; The polarizing and spectral filter array of claim 11 , wherein the fifth polarizing and spectral filter and the sixth polarizing and spectral filter each include the first reflector, the second reflector, and the grating layer.

16. the multiple first grating elements and the multiple second grating elements of the grating layer of the fifth polarizing spectral filter are rotated by 45° on a plane perpendicular to a first direction with respect to the multiple first grating elements and the multiple second grating elements of the grating layer of the first polarizing spectral filter; 16. The polarizing spectral filter array of claim 15, wherein the multiple first grating elements and the multiple second grating elements of the grating layer of the sixth polarizing spectral filter are rotated by 45° in a plane perpendicular to the first direction relative to the multiple first grating elements and the multiple second grating elements of the grating layer of the third polarizing spectral filter.

17. the first polarization spectral filter set further includes a fifth polarization spectral filter configured to transmit light having a first linear polarization component among light in a first wavelength band; the second polarization spectral filter set further includes a sixth polarization spectral filter configured to transmit light having a first linear polarization component from among light in the second wavelength band; The polarizing and spectral filter array of claim 11 , wherein the fifth polarizing and spectral filter and the sixth polarizing and spectral filter each include the first reflector, the second reflector, and the grating layer.

18. The polarizing spectral filter array according to any one of claims 11 to 17, an image sensor including a plurality of two-dimensionally arranged sensing pixels for sensing the intensity of light transmitted through the polarization spectroscopic filter array.

Images