Optical filter and spectrometer comprising an optical filter

Abstract

An optical filter and a spectrometer including the optical filter are provided. The optical filter includes at least one first filter element having a first center wavelength of a first wavelength band, and at least one second filter element arranged on a same plane as the at least one first filter element, the at least one second filter element having a second center wavelength of a second wavelength band. The at least one first filter element includes a first bandpass filter including a plurality of first Bragg reflection layers and at least one first cavity disposed between the plurality of first Bragg reflection layers, and a first multilayer disposed on the first bandpass filter, the first multilayer having a different center wavelength from the first center wavelength of the first Bragg reflection layers to block light of a wavelength band other than the first wavelength band.

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2020-0042970 filed with the Korean Intellectual Property Office on April 8, 2020 and Korean Patent Application No. 10-2020-0078814 filed with the Korean Intellectual Property Office on June 26, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to optical filters and spectrometers that include optical filters. Background Technology

[0004] Spectrometers are among the most important optical devices in the field of optics. However, due to the various optical components involved in existing spectrometers, they are large and bulky. Recently, there has been a demand to reduce the size of spectrometers; therefore, research has been conducted on simultaneously implementing integrated circuits and optical devices on semiconductor chips. Summary of the Invention

[0005] An optical filter and a spectrometer including the optical filter are provided.

[0006] Additional aspects will be set forth in part in the description which follows, and will also be apparent in part from the description, or may be learned by practicing the embodiments presented in this disclosure.

[0007] According to one aspect of this disclosure, an optical filter is provided, comprising: at least one first filter element having a first center wavelength in a first band; and at least one second filter element disposed on the same plane as the at least one first filter element, the at least one second filter element having a second center wavelength in a second band, wherein each of the at least one first filter element comprises: a first bandpass filter including a plurality of first Bragg reflectors and at least one first chamber disposed between the plurality of first Bragg reflectors; and a first multilayer disposed on the first bandpass filter, the center wavelength of the first multilayer being different from the first center wavelength of the plurality of first Bragg reflectors to block light in bands other than the first band.

[0008] Each of the plurality of first Bragg reflector layers and the first multilayer may have a structure in which a plurality of material layers having different refractive indices are stacked alternately, wherein each of the plurality of material layers in the first multilayer has a first thickness and is made of a first material, and wherein at least one of the first thickness or the first material is different from a second thickness or a second material of each of the plurality of material layers in the plurality of first Bragg reflector layers.

[0009] The first multilayer may include a third Bragg reflector layer, which comprises a material layer having the same optical thickness.

[0010] The first multilayer may include a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

[0011] The first pass filter may include a shortwave pass filter.

[0012] The first center wavelength of the first bandpass filter can be adjusted by changing the thickness or effective refractive index of at least one first chamber.

[0013] At least one second filter element may include: a second bandpass filter including a plurality of second Bragg reflectors and a second chamber between the plurality of second Bragg reflectors; and a second multilayer disposed on the second bandpass filter, the center wavelength of the second multilayer being different from the second center wavelength of the plurality of second Bragg reflectors to block light of other bands besides the second band.

[0014] Each of the plurality of second Bragg reflector layers and the second multilayer may have a structure in which a plurality of material layers having different refractive indices are stacked alternately, wherein the plurality of material layers in the second multilayer may have a third thickness and be made of a third material, and wherein at least one of the third thickness or the third material may be different from a fourth thickness or a fourth material of each of the plurality of material layers in the plurality of second Bragg reflector layers.

[0015] The material layer in each of the plurality of second Bragg reflector layers may be the same as the material layer in the first multilayer, and the material layer in the second multilayer may be the same as the material layer in each of the plurality of first Bragg reflector layers.

[0016] The second multilayer may include a fourth Bragg reflector layer, which comprises a material layer having the same optical thickness.

[0017] The second multilayer may include a second pass filter, which includes material layers, at least some of which have different optical thicknesses.

[0018] The second pass filter may include a long-pass filter.

[0019] The second center wavelength of the second bandpass filter can be adjusted by changing the thickness or effective refractive index of the second chamber.

[0020] At least one second filter element may include a second bandpass filter, which includes a plurality of second Bragg reflectors and a cavity disposed between the plurality of second Bragg reflectors, wherein the plurality of second Bragg reflectors include a material that absorbs light in the first band.

[0021] The optical filter may also include at least one third filter element arranged on the same plane as at least one first filter element and at least one second filter element, wherein the at least one third filter element has a third center wavelength between the first band and the second band.

[0022] The optical filter may also include: an additional filter disposed on at least one first filter element and at least one second filter element to transmit only a specific wavelength band.

[0023] Additional filters may include color filters or broadband filters.

[0024] The optical filter may further include: a short-wavelength absorbing filter disposed on some of at least one first filter element and at least one second filter element, and a long-wavelength blocking filter disposed on some of the other of at least one first filter element and at least one second filter element.

[0025] According to another aspect of this disclosure, an optical filter is provided, comprising: a plurality of filter elements arranged on a coplanar plane, the plurality of filter elements having a center wavelength in a different band, wherein each of the plurality of filter elements includes: a plurality of material layers having different refractive indices from each other; and a cavity disposed between the plurality of material layers, wherein the plurality of material layers have a thickness that gradually increases in a first direction.

[0026] The center wavelength of multiple filter elements can be adjusted by changing the position of the chambers of the corresponding filter elements in multiple filter elements.

[0027] According to another aspect of this disclosure, a spectrometer is provided, comprising: an optical filter; and a sensing device for receiving light transmitted through the optical filter; wherein the optical filter comprises: at least one first filter element having a first center wavelength within a first band; and at least one second filter element disposed on the same plane as the at least one first filter element, the at least one second filter element having a second center wavelength within a second band, the at least one first filter element comprising: a first bandpass filter including a plurality of first Bragg reflectors and at least one first chamber disposed between the plurality of first Bragg reflectors; and a first multilayer disposed on the first bandpass filter, the center wavelength of the first multilayer being different from the first center wavelength of the plurality of first Bragg reflectors to block light of other bands besides the first band.

[0028] Each of the plurality of first Bragg reflector layers and the first multilayer may have a structure in which a plurality of material layers having different refractive indices are stacked alternately, wherein each of the plurality of material layers in the first multilayer has a first thickness and is made of a first material, and wherein at least one of the first thickness or the first material is different from a second thickness or a second material of each of the plurality of material layers in the plurality of first Bragg reflector layers.

[0029] The first multilayer may include a third Bragg reflector layer, which comprises a material layer having the same optical thickness.

[0030] The first multilayer may include a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

[0031] The first center wavelength of the first bandpass filter can be adjusted by changing the thickness or effective refractive index of at least one first chamber.

[0032] At least one second filter element may include: a second bandpass filter including a plurality of second Bragg reflectors and a second chamber between the plurality of second Bragg reflectors; and a second multilayer disposed on the second bandpass filter, the center wavelength of the second multilayer being different from the second center wavelength of the plurality of second Bragg reflectors to block light of other bands besides the second band.

[0033] Each of the plurality of second Bragg reflector layers and the second multilayer may have a structure in which a plurality of material layers having different refractive indices are stacked alternately, wherein the plurality of material layers in the second multilayer may have a third thickness and be made of a third material, and wherein at least one of the third thickness or the third material is different from a fourth thickness or a fourth material of each of the plurality of material layers in the plurality of second Bragg reflector layers.

[0034] The second multilayer may include a fourth Bragg reflector layer, which comprises a material layer having the same optical thickness.

[0035] The second multilayer may include a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

[0036] The second center wavelength of the second bandpass filter can be adjusted by changing the thickness or effective refractive index of the second chamber.

[0037] At least one second filter element may include a second bandpass filter, which includes a plurality of second Bragg reflectors and a cavity disposed between the plurality of second Bragg reflectors, wherein the plurality of second Bragg reflectors include a material that absorbs light in the first band.

[0038] The optical filter may also include at least one third filter element arranged on the same plane as at least one first filter element and at least one second filter element, and the at least one third filter element may have a third center wavelength between the first band and the second band.

[0039] The optical filter may also include: an additional filter disposed on at least one first filter element and at least one second filter element to transmit only a specific wavelength band.

[0040] The spectrometer may also include: a short-wavelength absorption filter disposed on some of at least one first filter element and at least one second filter element, and a long-wavelength blocking filter disposed on some of the other of at least one first filter element and at least one second filter element.

[0041] According to another aspect of this disclosure, an optical filter is provided, comprising: a first bandpass filter having a first center wavelength within a first band, the first bandpass filter including a plurality of first Bragg reflector layers and at least one first cavity disposed between the plurality of first Bragg reflector layers; a first multilayer disposed on the first bandpass filter, the first multilayer having a plurality of first material layers configured to block light of a band different from the first band; a second bandpass filter having a second center wavelength within a second band, the second bandpass filter including a plurality of second Bragg reflector layers and at least one second cavity disposed between the plurality of second Bragg reflector layers; and a second multilayer disposed on the second bandpass filter, the second multilayer having a plurality of second material layers configured to block light of a band different from the second band, wherein the first bandpass filter and the first multilayer are disposed on the same plane as the second bandpass filter and the second multilayer.

[0042] According to another aspect of this disclosure, an optical filter is provided, comprising: a first filter bank including: a plurality of first bandpass filters; and a plurality of first multilayers disposed on the plurality of first bandpass filters; and a second filter bank including: a plurality of second bandpass filters; and a plurality of second multilayers disposed on the plurality of second bandpass filters, wherein the plurality of first bandpass filters includes: a bandpass filter having a first center wavelength within a first band, and a bandpass filter having a second center wavelength within the first band, and wherein the plurality of first multilayers are configured to block light of a band different from the first band. Attached Figure Description

[0043] The above and other aspects, features, and advantages of some embodiments of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0044] Figure 1 This is a perspective view of a spectrometer according to an example embodiment;

[0045] Figure 2 It is along Figure 1 A cross-sectional view of the optical filter intercepted by line II-II′;

[0046] Figure 3 yes Figure 2 Cross-sectional view of the first bandpass filter bank;

[0047] Figure 4 It shows Figure 2 A cross-sectional view of the first multi-layer example;

[0048] Figure 5 It shows Figure 3 A diagram showing an example of the transmission spectrum of the first bandpass filter bank;

[0049] Figure 6 It shows the composition Figure 4 A diagram showing the optical thickness of the material layer of the second Bragg reflector;

[0050] Figure 7 It shows Figure 6 A diagram illustrating an example of the transmission spectrum of the second Bragg reflector;

[0051] Figure 8 It shows Figure 2 A diagram showing an example of the transmission spectrum of the first filter bank;

[0052] Figure 9 yes Figure 2 Cross-sectional view of the second bandpass filter bank;

[0053] Figure 10 It shows Figure 2A cross-sectional view of the second multilayer example;

[0054] Figure 11 It shows Figure 9 A diagram showing an example of the transmission spectrum of the second bandpass filter bank;

[0055] Figure 12 It shows the composition Figure 10 A diagram showing the optical thickness of the material layer of the first Bragg reflector;

[0056] Figure 13 It shows Figure 12 A diagram illustrating an example of the transmission spectrum of the first Bragg reflector;

[0057] Figure 14 It shows Figure 2 A diagram showing an example of the transmission spectrum of the second filter bank;

[0058] Figure 15 It shows Figure 2 A figure showing an example of the transmission spectrum of an optical filter;

[0059] Figure 16 It shows Figure 2 A cross-sectional view of another example of the first multilayer;

[0060] Figure 17 It shows the composition Figure 16 A diagram illustrating an example of the optical thickness of the material layer in the first pass filter;

[0061] Figure 18 It shows Figure 17 A diagram showing an example of the transmission spectrum of the first pass filter;

[0062] Figure 19 It shows how to adjust the composition Figure 16 An example of a transmission spectrum obtained by measuring the optical thickness of the material layer of the first pass filter;

[0063] Figure 20 It shows Figure 2 A cross-sectional view of another example of the second multilayer;

[0064] Figure 21 It shows the composition Figure 20 A diagram illustrating an example of the optical thickness of the material layer in the second-pass filter;

[0065] Figure 22 It shows Figure 21 A figure showing an example of the transmission spectrum of the second-pass filter;

[0066] Figure 23 It shows the use of Figure 21A diagram showing an example of the transmission spectrum of the second filter bank of the second pass filter;

[0067] Figure 24 It shows how to adjust the composition Figure 20 An example of the transmission spectrum obtained by measuring the optical thickness of the material layer of the second-pass filter;

[0068] Figure 25 It shows that it can be done Figure 2 A diagram of another example of the first bandpass filter bank used in an optical filter;

[0069] Figure 26 It shows that it can be done Figure 2 A figure showing another example of the second bandpass filter bank used in an optical filter;

[0070] Figure 27 It shows that it can be done Figure 2 A figure showing another example of a bandpass filter used in optical filters;

[0071] Figure 28 It shows that it can be done Figure 2 A diagram showing another example of multilayers used in optical filters;

[0072] Figure 29 This is a cross-sectional view of an optical filter according to another example embodiment;

[0073] Figure 30 It shows Figure 29 A figure showing an example of the transmission spectrum of an optical filter;

[0074] Figure 31 This is a cross-sectional view of an optical filter according to another example embodiment;

[0075] Figure 32 It shows Figure 31 A diagram showing an example of the transmission spectrum of the first filter unit;

[0076] Figure 33 It shows Figure 31 A figure showing an example of the transmission spectrum of the second filter unit;

[0077] Figure 34 This is a cross-sectional view of an optical filter according to another example embodiment;

[0078] Figure 35 This is a cross-sectional view of an optical filter according to another example embodiment;

[0079] Figure 36 It shows Figure 35 A figure showing an example of the transmission spectrum of an optical filter;

[0080] Figure 37 This is a cross-sectional view of an optical filter according to another example embodiment;

[0081] Figure 38 It shows that it can be used as Figure 37 A diagram illustrating an example of a broadband filter with an additional filter;

[0082] Figure 39 It shows that it can be used as Figure 37 A diagram of another example of a broadband filter with an additional filter; and

[0083] Figure 40 This is a cross-sectional view of an optical filter according to another example embodiment. Detailed Implementation

[0084] Referring now to the embodiments, examples of which are illustrated in the accompanying drawings, wherein similar reference numerals throughout the drawings denote similar elements. In this respect, the presented embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, exemplary embodiments are described below only with reference to the accompanying drawings to explain various aspects. The term “and / or” as used herein includes any and all combinations of one or more of the related listed items. Expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than modifying individual elements in the list.

[0085] In the following, one or more exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, similar reference numerals denote similar components, and the dimensions of components may be enlarged for ease of illustration. Embodiments of the present disclosure are subject to various modifications and can be embodied in many different forms.

[0086] When a layer, film, region, or panel is referred to as being "on" another element, it can be directly on another layer or substrate, or an intermediate layer may be present. The singular form encompasses the plural form unless there is a clear distinction in the context. Throughout the specification, when a section "includes" an element, it may also include another element, without excluding the presence of that other element, unless otherwise stated.

[0087] As used herein, specifically, terms such as “the” and similar indicators used herein may indicate both the singular and the plural. Furthermore, the steps of all the methods described herein may be performed in any suitable order, unless otherwise indicated herein or explicitly stated otherwise by the context.

[0088] Furthermore, terms such as “...unit” and “module” provided herein refer to units that perform at least one function or operation and can be implemented as hardware, software or a combination of hardware and software.

[0089] Furthermore, the connecting lines or connectors shown in the accompanying drawings are intended to illustrate example functional relationships and / or physical or logical connections between various components. It should be noted that many alternative or additional functional relationships, physical connections, or logical connections may exist in actual equipment.

[0090] Unless otherwise required, the use of any and all examples or example languages ​​provided herein is intended only to better illustrate this disclosure and does not impose any limitation on the scope of this disclosure.

[0091] Figure 1 This is a perspective view of a spectrometer 1000 according to an example embodiment. Figure 2 It is along Figure 1 A cross-sectional view of the optical filter 1100 taken from line II-II′.

[0092] refer to Figure 1 and Figure 2 The spectrometer 1000 includes a sensing device 2400 and an optical filter 1100 disposed on the sensing device 2400. The optical filter 1100 may include a plurality of filter units arranged in a two-dimensional manner. However, one or more embodiments are not limited thereto, and the plurality of filter units may be arranged in a one-dimensional manner. Figure 2 Cross sections of six filter units 110, 120, 130, 210, 220 and 230 are shown as an example.

[0093] Sensing device 2400 can receive light that has passed through optical filter 1100 and convert the light into an electrical signal. The light passing through filter 1100 reaches a pixel of sensing device 2400. Sensing device 2400 converts the light incident on the pixel into an electrical signal to perform spectral analysis on the light incident on optical filter 1100. Sensing device 2400 may include, for example, an image sensor (e.g., a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS) image sensor, etc.) or a photodiode. However, one or more example embodiments are not limited thereto.

[0094] Optical filter 1100 may include a first filter group 100 and a second filter group 200 on the same plane. Here, the first filter group 100 may include first filter units to third filter units 110, 120 and 130, and the second filter group 200 may include fourth filter units to sixth filter units 210, 220 and 230. However, one or more exemplary embodiments of this disclosure are not limited thereto, and the number of filter units included in each of the first filter group 100 and the second filter group 200 may vary.

[0095] The first filter bank 100 may include a first bandpass filter bank 100a and a first multilayer 100b on the first bandpass filter bank 100a. The first bandpass filter bank 100a may have a center wavelength in a first band (e.g., about 400 nm to 550 nm), and the first multilayer 100b may block light in other bands besides the first band.

[0096] Figure 3 A cross-section of the first bandpass filter bank 100a is shown, and Figure 4 An example of the first multilayer 100b is shown.

[0097] Reference Figure 3 and Figure 4 The first bandpass filter bank 100a may include first bandpass filters to third bandpass filters 110a, 120a, and 130a having center wavelengths that are different from each other within a first band (e.g., about 400 nm to about 550 nm). The first bandpass filter 110a and the first multilayer 100b may form a first filter unit 110, the second bandpass filter 120a and the first multilayer 100b may form a second filter unit 120, and the third bandpass filter 130a and the first multilayer 100b may form a third filter unit 130.

[0098] Each bandpass filter transmits a band of light with a specific center wavelength and has a Fabry-Perot structure in which a cavity is positioned between two reflective layers. The center wavelength and band of light passing through the bandpass filter can be determined based on the reflection bands of the reflective layers and the characteristics of the cavity.

[0099] Each of the first to third bandpass filters 110a, 120a, and 130a includes two first Bragg reflectors 151 and a cavity 161, 162, or 163 between the first Bragg reflectors 151. The first to third bandpass filters 110a, 120a, and 130a may each include a first cavity 161, 162, and 163. The first Bragg reflector 151 may be a distributed Bragg reflector (DBR).

[0100] Each of the first Bragg reflector layers 151 may have a structure in which a first material layer 151a and a second material layer 151b with different refractive indices are alternately stacked. The first material layer 151a and the second material layer 151b may have the same optical thickness. Here, optical thickness refers to a thickness that reflects the wavelength and the refractive index of the incident light, in addition to physical thickness. In the following, the term "thickness" refers to physical thickness.

[0101] For example, the first material layer 151a and the second material layer 151b may comprise silicon oxide and titanium oxide. In another example, the first material layer 151a and the second material layer 151b may comprise silicon oxide and silicon. However, one or more example embodiments are not limited thereto, and the first material layer 151a and the second material layer 151b may comprise a variety of other materials. Silicon may have a refractive index of about 3.0 or greater, silicon oxide may have a refractive index of about 1.4 to 1.5, and titanium oxide may have a refractive index of about 1.9 to 3.0.

[0102] The cavities 161, 162, and 163 between the first Bragg reflector layers 151 may include a dielectric material with a specific refractive index as a resonant layer. For example, cavities 161, 162, and 163 may include silicon, silicon oxide, or titanium oxide. When light passes through the first Bragg reflector layer 151 and is incident into the first to third cavities 161, 162, and 163, the light oscillates within these cavities, resulting in both constructive and destructive interference. Furthermore, the first to third bandpass filters 110a, 120a, and 130a output light with a specific center wavelength that satisfies the constructive interference condition.

[0103] The thickness of the first chamber 161 can be less than the thickness of the second chamber 162, and the thickness of the third chamber 163 can be greater than the thickness of the second chamber 162. Therefore, the first center wavelength of the first bandpass filter 110a can be less than the second center wavelength of the second bandpass filter 120a, and the third center wavelength of the third bandpass filter 130a can be greater than the second center wavelength of the second bandpass filter 120a.

[0104] The first multilayer 100b is on the first bandpass filter bank 100a. Here, the first multilayer 100b may be a second Bragg reflector 152. Similar to the first Bragg reflector 151, the second Bragg reflector 152 may include a DBR. Here, the reflection band of the second Bragg reflector 152 may be different from the reflection band of the first Bragg reflector 151.

[0105] The second Bragg reflector 152 may have a structure in which a third material layer 152a and a fourth material layer 152b with different refractive indices are alternately stacked. Here, the third material layer 152a and the fourth material layer 152b may have equal optical thicknesses.

[0106] The third material layer 152a and the fourth material layer 152b may include, but are not limited to, the same materials as the first material layer 151a and the second material layer 151b. For example, the third material layer 152a and the fourth material layer 152b may include silicon oxide and titanium oxide. In another example, the third material layer 152a and the fourth material layer 152b may include silicon oxide and silicon. However, one or more example embodiments are not limited thereto, and the third material layer 152a and the fourth material layer 152b may include a variety of other materials.

[0107] At least one of the materials and thicknesses of the third material layer 152a and the fourth material layer 152b may differ from at least one of the materials and thicknesses of the first material layer 151a and the second material layer 151b, such that the reflection band of the second Bragg reflector layer 152 may differ from the reflection band of the first Bragg reflector layer 151. For example, when the third material layer 152a and the fourth material layer 152b are the same as the first material layer 151a and the second material layer 151b, the thicknesses of the third material layer 152a and the fourth material layer 152b may differ from the thicknesses of the first material layer 151a and the second material layer 151b. Figure 4 An example is shown in which the thickness of the third material layer 152a and the fourth material layer 152b is greater than the thickness of the first material layer 151a and the second material layer 151b.

[0108] The third material layer 152a and the fourth material layer 152b may comprise materials different from those of the first material layer 151a and the second material layer 151b. In this case, the thickness of the third material layer 152a and the fourth material layer 152b may be the same as or different from the thickness of the first material layer 151a and the second material layer 151b.

[0109] Figure 5 It shows Figure 3 A figure showing an example of the transmission spectrum of the first bandpass filter bank 100a. (Refer to...) Figure 5 The first bandpass filter bank 100a transmits light in the undesired band (SA) and light in the first band (approximately 400 nm to approximately 550 nm).

[0110] Figure 6 It shows that it includes Figure 4 The optical thickness of the third material layer 152a and the fourth material layer 152b in the second Bragg reflector layer 152. Figure 6In this context, full-wave optical thickness (FWOT) represents optical thickness and can be defined as "(thickness × refractive index) / wavelength of incident light". Here, the wavelength of the incident light represents the center wavelength of the photonic bandgap blocked by the second Bragg reflector.

[0111] Reference Figure 6 The third material layer 152a and the fourth material layer 152b, which are included in the second Bragg reflector layer 152, have equal optical thicknesses. The optical thickness (FWOT) of the third material layer 152a and the fourth material layer 152b can be, for example, about 0.25.

[0112] Figure 7 It shows Figure 6 A diagram illustrating an example of the transmission spectrum of the second Bragg reflector 152. (Refer to...) Figure 7 The second Bragg reflector 152 mainly reflects light in other wavelengths besides the first wavelength (approximately 400 nm to approximately 550 nm).

[0113] Figure 8 It shows Figure 2 A diagram showing an example of the transmission spectrum of the first filter bank 100. (Refer to...) Figure 8 The second Bragg reflector layer 152 on the first bandpass filter bank 100a blocks light of another band (about 400 nm to about 550 nm) other than the first band. Therefore, the first filter bank 100 can transmit only the light of the first band (i.e., the desired band).

[0114] In the above description, the first multilayer 100b is on the first bandpass filter group 100a, but the first multilayer 100b can be below or beneath the first bandpass filter group 100a. That is, according to the example embodiment, the first multilayer 100b can be disposed on the top surface of the first bandpass filter group 100a, or the first multilayer 100b can be disposed on the bottom surface of the first bandpass filter group 100a. According to the example embodiment, the first multilayer 100b can be disposed on both the top and bottom surfaces of the first bandpass filter group 100a.

[0115] The second filter bank 200 may include a second multilayer 200b and a second bandpass filter bank 200a on the second multilayer 200b. The second bandpass filter bank 200a may have a center wavelength in a second band (e.g., about 550 nm to 700 nm), and the second multilayer 200b may block light in other bands besides the second band.

[0116] Figure 9 A cross-section of the second bandpass filter bank 200a is shown, and Figure 10 An example of the second multilayer 200b is shown.

[0117] Reference Figure 9 and Figure 10 The second multilayer 200b may include a first Bragg reflector 252. Here, except for the number of layers, the first Bragg reflector 252 may be the same as the first Bragg reflector 151 in the first filter bank 100. The reflection band of the first Bragg reflector 252 may be different from the reflection band of the second Bragg reflector 251, which will be described later.

[0118] The first Bragg reflector layer 252 may have a structure in which a first material layer 252a and a second material layer 252b with different refractive indices are alternately stacked. Here, the first material layer 252a and the second material layer 252b may have equal optical thicknesses.

[0119] The second bandpass filter bank 200a is mounted on the second multilayer 200b. The second bandpass filter bank 200a may include a fourth bandpass filter 210a, a fifth bandpass filter 220a, and a sixth bandpass filter 230a, each having a different center wavelength within a second band (e.g., from about 550 nm to about 700 nm). The fourth bandpass filter 210a and the second multilayer 200b form a fourth filter unit 210, the fifth bandpass filter 220a and the second multilayer 200b form a fifth filter unit 220, and the sixth bandpass filter 230a and the second multilayer 200b form a sixth filter unit 230.

[0120] Each of the fourth bandpass filter 210a, the fifth bandpass filter 220a, and the sixth bandpass filter 230a includes two second Bragg reflectors 251 and a cavity 261, 262, or 263 between the two second Bragg reflectors 251. Here, the fourth bandpass filter 210a, the fifth bandpass filter 220a, and the sixth bandpass filter 230a may each include a fourth cavity 261, a fifth cavity 262, and a sixth cavity 263 with different thicknesses. Each of the second Bragg reflectors 251 may be a DBR (Diverterless Bragg Filter).

[0121] Except for the number of layers, each of the second Bragg reflector layers 251 can be the same as the second Bragg reflector layer 152 in the first filter group 100. The second Bragg reflector layer 251 can have a structure in which a third material layer 251a and a fourth material layer 251b with different refractive indices are alternately stacked. Here, the third material layer 251a and the fourth material layer 251b can have equal optical thicknesses.

[0122] At least one of the materials and thicknesses of the third material layer 251a and the fourth material layer 251b may differ from at least one of the materials and thicknesses of the first material layer 252a and the second material layer 252b, such that the reflection band of the second Bragg reflector layer 251 may differ from the reflection band of the first Bragg reflector layer 252. For example, when the third material layer 251a and the fourth material layer 251b are the same as the first material layer 252a and the second material layer 252b, the thicknesses of the third material layer 251a and the fourth material layer 251b may differ from the thicknesses of the first material layer 252a and the second material layer 252b. Figure 9 An example is shown in which the thickness of the third material layer 251a and the fourth material layer 251b is greater than the thickness of the first material layer 252a and the second material layer 252b.

[0123] The cavities 261, 262, and 263 between the second Bragg reflector layers 251 may include a dielectric material with a specific refractive index as a resonant layer. For example, cavities 261, 262, and 263 may include silicon, silicon oxide, or titanium oxide.

[0124] The thickness of the fourth chamber 261 can be less than the thickness of the fifth chamber 262, and the thickness of the sixth chamber 263 can be greater than the thickness of the fifth chamber 262. Therefore, in the second bandpass filter bank 200a, the fourth center wavelength of the fourth bandpass filter 210a is less than the fifth center wavelength of the fifth bandpass filter 220a, and the sixth center wavelength of the sixth bandpass filter 230a can be greater than the fifth center wavelength of the fifth bandpass filter 220a.

[0125] Figure 11 It shows Figure 9 Example of the transmission spectrum of the second bandpass filter bank. (Refer to...) Figure 11 The second bandpass filter bank 200a transmits light from the undesired band SB and light from the second band (approximately 550 nm to approximately 700 nm).

[0126] Figure 12 It shows Figure 10 The optical thicknesses of the first material layer 252a and the second material layer 252b in the first Bragg reflector layer 252. (Refer to...) Figure 12 The first material layer 252a and the second material layer 252b in the first Bragg reflector layer 252 have equal optical thicknesses. The optical thickness (FWOT) of the first material layer 252a and the second material layer 252b can be, for example, about 0.25.

[0127] Figure 13 It shows Figure 12 A diagram illustrating an example of the transmission spectrum of the first Bragg reflector 252. (Refer to...) Figure 13The first Bragg reflector 252 mainly reflects light in other wavelength bands except for the second band (approximately 550 nm to approximately 700 nm).

[0128] Figure 14 It shows Figure 2 A figure showing an example of the transmission spectrum of the second filter bank 200. (Refer to...) Figure 14 The first Bragg reflector layer 252, located below the second bandpass filter group 200a, blocks light of other bands except the second band (approximately 550 nm to approximately 700 nm). Therefore, the second filter group 200 can transmit only the desired second band of light.

[0129] In the above description, the first Bragg reflector 252 is disposed below the second bandpass filter group 200a, but the first Bragg reflector 252 may be disposed above the second bandpass filter group 200a.

[0130] Figure 15 It shows Figure 2 A figure showing an example of the transmission spectrum of the optical filter 1100. (Refer to...) Figure 15 Because the second Bragg reflector 152 blocks light of the undesirable wavelength band of the first bandpass filter group 100a, the first filter group 100 can transmit only light of the first wavelength band (e.g., about 400 nm to about 550 nm). Similarly, because the first Bragg reflector 252 blocks light of the undesirable wavelength band of the second bandpass filter group 200a, the second filter group 200 can transmit only light of the second wavelength band (e.g., about 550 nm to about 700 nm). Therefore, the optical filter 1100 according to the example embodiment can achieve broadband characteristics by transmitting only light of the first and second wavelength bands.

[0131] Figure 16 It shows Figure 2 A cross-sectional view of another example of the first multilayer 100b.

[0132] Reference Figure 16 The first multilayer 100b of the first filter bank 100 may include a first pass filter 152'. The first pass filter 152' may be a short-pass filter that transmits only light of a specific wavelength (e.g., about 550 nm) or smaller.

[0133] Except for the layer thickness, the first pass filter 152' can be the same as the second Bragg reflector layer 152 of the first filter bank 100 described above. Specifically, the first pass filter 152' can have a structure in which a third material layer 152'a and a fourth material layer 152'b with different refractive indices are alternately stacked. Here, at least some of the third material layer 152'a and the fourth material layer 152'b can have different thicknesses.

[0134] Figure 17 It shows Figure 16 An example of the optical thickness of the third material layer 152'a and the fourth material layer 152'b in the first pass filter 152'. See also... Figure 17 In the third material layer 152'a and the fourth material layer 152'b included in the first pass filter 152' (i.e., the short-pass filter), the optical thickness of the outermost material layer (152'b) is greater than the optical thickness of the other material layers 152'a and 152'b. For example, the optical thickness (FWOT) of the outermost material layer (152'b) can be greater than about 0.25 and less than about 0.5. Conversely, the optical thickness (FWOT) of the innermost material layers 152'a and 152'b can be about 0.25.

[0135] Figure 18 It shows Figure 17 An example of the transmission spectrum of the second pass filter 152' is shown. (Refer to...) Figure 18 Compared to the second Bragg reflector 152 described above, the first pass filter 152' has excellent transmission characteristics for a specific wavelength (e.g., about 550 nm) or shorter wavelengths.

[0136] In the above description, an example is shown of changing the optical thickness of the two outermost fourth material layers 152'b, which are included in the third material layer 152'a and the fourth material layer 152'b in the first pass filter 152'. However, according to the example embodiment, the optical thickness of the third material layer 152'a and the fourth material layer 152'b can have various variations.

[0137] Figure 19 An example of a transmission spectrum obtained by adjusting the optical thickness of the third material layer 152'a and the fourth material layer 152'b included in the first pass filter 152' is shown. (Refer to...) Figure 19 Excellent transmission characteristics can be achieved by adjusting the optical thickness of the third material layer 152'a and the fourth material layer 152'b included in the first pass filter 152'.

[0138] Figure 20 It shows Figure 2 A cross-sectional view of another example of the second multilayer 200b.

[0139] Reference Figure 20 The second multilayer 200b of the second filter bank 200 may include a second pass filter 252'. The second pass filter 252' may be a long-pass filter that transmits only light of a specific wavelength (e.g., about 550 nm) or a longer wavelength.

[0140] Except for the layer thickness, the second pass filter 252' can be the same as the first Bragg reflector layer 252 of the second filter bank 200 described above. Specifically, the second pass filter 252' can have a structure in which first material layers 252'a and second material layers 252'b with different refractive indices are alternately stacked. Here, the thickness of at least some of the first material layers 252'a and second material layers 252'b can be different from the thickness of the other material layers.

[0141] Figure 21 It shows Figure 20 An example of the optical thickness of the first material layer 252'a and the second material layer 252'b in the second pass filter 252'. See also... Figure 21 In the first material layer 252'a and the second material layer 252'b included in the second pass filter 252' (i.e., the long-pass filter), the optical thickness of the two outermost material layers 252'b is smaller than the optical thickness of the other material layers 252'a and 252'b. For example, the optical thickness (FWOT) of the outermost material layer 252'b can be greater than about 0.1 and less than about 0.25. Additionally, the optical thickness (FWOT) of the inner material layers 252'a and 252'b can be about 0.25.

[0142] Figure 22 It shows Figure 21 An example of the transmission spectrum of the second pass filter 252' is shown. (Refer to...) Figure 22 Compared with the first Bragg reflector 252 mentioned above, the second pass filter 252' has excellent transmission characteristics for a specific wavelength (e.g., about 550 nm) or a larger wavelength.

[0143] Figure 23 It shows the use of Figure 21 A diagram illustrating an example of the transmission spectrum of the second filter bank 200 of the second pass filter 252'. (Refer to...) Figure 23 , and adoption Figure 14 Compared to the transmission spectrum of the second filter group 200 with the first Bragg reflector layer 252 shown, the transmission spectrum of the second filter group 200 with the second pass filter 252′ has excellent transmission characteristics.

[0144] In the above description, an example is shown of changing the optical thickness of the two outermost second material layers 252'b, which are included in the first material layer 252'a and the second material layer 252'b in the second pass filter 252'. However, according to the example embodiment, the optical thickness of the first material layer 252'a and the second material layer 252'b can have various variations.

[0145] Figure 24An example of a transmission spectrum obtained by adjusting the optical thickness of the first material layer 252'a and the second material layer 252'b included in the second pass filter 252' is shown. (Refer to...) Figure 24 Excellent transmission characteristics can be achieved by adjusting the optical thickness of the first material layer 252'a and the second material layer 252'b included in the second pass filter 252'.

[0146] Figure 25 This illustrates a possible implementation according to another example embodiment. Figure 2 A diagram illustrating an example of the first bandpass filter bank 500a used in the optical filter 1100. Besides chambers 561, 562, and 563... Figure 25 The first bandpass filter bank 500a shown is... Figure 3 The first bandpass filter group 100a is the same.

[0147] Reference Figure 25 The first bandpass filter group 500a may include a first bandpass filter 510a, a second bandpass filter 520a, and a third bandpass filter 530a, each having a center wavelength different from the others within a first band. Each of the first bandpass filter 510a, the second bandpass filter 520a, and the third bandpass filter 530a includes two first Bragg reflectors 151 and a cavity 561, 562, or 563 between the first Bragg reflectors 151. Here, the first bandpass filter 510a, the second bandpass filter 520a, and the third bandpass filter 530a may each include a first cavity 561, a second cavity 562, and a third cavity 563, each having an effective refractive index different from the others.

[0148] The first chamber 561 may have a structure in which a first material layer M1 and a second material layer M2 with different refractive indices are alternately stacked. For example, the first material layer M1 may comprise silicon, and the second material layer M2 may comprise silicon oxide. However, one or more embodiments are not limited thereto, and the first and second material layers may comprise a variety of other materials.

[0149] Figure 25 An example is shown in which the first material layer and the second material layer are arranged in a direction perpendicular to the first Bragg reflector 151. However, one or more example embodiments are not limited thereto, and the first material layer and the second material layer may be arranged parallel to the first Bragg reflector 151, or may be arranged in two dimensions.

[0150] The second chamber 562 may include a first material layer and a second material layer with widths different from those of the first chamber 561, and therefore may have an effective refractive index different from that of the first chamber 561. Similarly, the third chamber 563 may include a first material layer and a second material layer with widths different from those of the first chamber 561 and the second chamber 562, and therefore may have an effective refractive index different from that of the first chamber 561 and the second chamber 562. As described above, the first chamber 561, the second chamber 562, and the third chamber 563 can achieve different center wavelengths by using different effective refractive indices.

[0151] For example, the second material layer M2 in the first chamber 561 may have multiple first second material layer portions, the second material layer M2 in the second chamber 562 may have multiple second second material layer portions, and the second material layer M2 in the second chamber 563 may have multiple third second material layer portions. Furthermore, the width of each of the multiple first second material layer portions is different from the width of each of the multiple second second material layer portions, and the width of each of the multiple third second material layer portions is different from the width of each of the multiple second second material layer portions.

[0152] Figure 26 It shows that it can be done Figure 2 A diagram illustrating an example of the second bandpass filter bank 600a used in the optical filter 1100. Besides chambers 661, 662, and 663... Figure 26 The second bandpass filter bank 600a shown is... Figure 9 The second bandpass filter bank 200a is the same.

[0153] Reference Figure 26 The second bandpass filter bank 600a may include a fourth bandpass filter 610a, a fifth bandpass filter 620a, and a sixth bandpass filter 630a, each having a center wavelength different from the others within the second band. Each of the fourth bandpass filter 610a, the fifth bandpass filter 620a, and the sixth bandpass filter 630a includes two second Bragg reflectors 251 and a cavity 661, 662, or 663 between the two second Bragg reflectors 251. Here, the fourth bandpass filter 610a, the fifth bandpass filter 620a, and the sixth bandpass filter 630a may each include a fourth cavity 661, a fifth cavity 662, and a sixth cavity 663, each having an effective refractive index different from the others.

[0154] The fourth chamber 661 may have a structure in which first and second material layers with different refractive indices are alternately stacked. For example, the first material layer may comprise silicon, and the second material layer may comprise silicon oxide. However, one or more embodiments are not limited thereto, and the first and second material layers may comprise a variety of other materials.

[0155] Figure 26 An example is shown in which the first and second material layers are arranged in a direction perpendicular to the second Bragg reflector 251. However, one or more embodiments are not limited thereto, and the first and second material layers may be arranged parallel to the second Bragg reflector 251, or may be arranged in two dimensions.

[0156] The fifth chamber 662 may include a first material layer and a second material layer with widths different from those of the fourth chamber 661, and therefore may have an effective refractive index different from that of the fourth chamber 661. Similarly, the sixth chamber 663 may include a first material layer and a second material layer with widths different from those of the fourth and fifth chambers 661 and 662, and therefore may have an effective refractive index different from those of the fourth and fifth chambers 661 and 662. As described above, the fourth chamber 661, the fifth chamber 662, and the sixth chamber 663 can achieve different center wavelengths by using different effective refractive indices.

[0157] Figure 27 It shows that it can be done Figure 2 A diagram showing an example of another bandpass filter 700 used in the optical filter 1100. Figure 27 The bandpass filter 700 can be applied to Figure 2 The first bandpass filter group 100a and the second bandpass filter group 200a.

[0158] Reference Figure 27 The bandpass filter 700 includes three Bragg reflectors 751 spaced apart from each other and two chambers 760 between the Bragg reflectors 751. Here, the Bragg reflectors 751 may be DBRs. Figure 27 An example is shown in which the bandpass filter 700 includes two chambers 760, but the bandpass filter 700 may include three or more chambers 760.

[0159] Figure 28 It shows that it can be used Figure 2 Another example of a multilayer 800 used in the optical filter 1100. Figure 28 Multi-layer 800 can be applied to Figure 2 The first layer is 100b and the second layer is 200b.

[0160] Reference Figure 28The multilayer 800 includes a first Bragg reflector 852 and a second Bragg reflector 853 stacked on the first Bragg reflector 852. The reflection bands of the first Bragg reflector 852 and the second Bragg reflector 853 may differ from the reflection bands of the Bragg reflectors in the bandpass filter of the multilayer 800. Various modifications can be made to the position of the bandpass filter on the multilayer 800. For example, the bandpass filter may be above or below the first Bragg reflector 852 and the second Bragg reflector 853, or it may be between the first Bragg reflector 852 and the second Bragg reflector 853.

[0161] The first Bragg reflector layer 852 may have a structure in which a first material layer 852a and a second material layer 852b with different refractive indices are alternately stacked, and the second Bragg reflector layer 853 may have a structure in which a third material layer 853a and a fourth material layer 853b with different refractive indices are alternately stacked. Here, at least one of the material and thickness of the third material layer 853a and the fourth material layer 853b may be different from the material and thickness of the first material layer 852a and the second material layer 852b. Figure 28 An example is shown in which the multilayer 800 includes two Bragg reflector layers, namely, a first Bragg reflector layer 852 and a second Bragg reflector layer 853, but the multilayer 800 may include three or more Bragg reflector layers.

[0162] Figure 29 This is a cross-sectional view of an optical filter 1200 according to another example embodiment. The differences between the optical filter 1200 and the optical filter of the example embodiment described above will be described below.

[0163] Reference Figure 29 The optical filter 1200 includes a first filter group 100, a second filter group 200, and a third filter group 300 arranged on the same plane. The first filter group 100 includes first to third filter units 110, 120, and 130, and the second filter group 200 includes fourth to sixth filter units 210, 220, and 230. The first filter group 100 may have a center wavelength in a first band, and the second filter group 200 may have a center wavelength in a second band. The first filter group 100 and the second filter group 200 are... Figure 2 The first filter bank 100 and the second filter bank 200 shown are the same, so their descriptions are omitted.

[0164] The third filter bank 300 includes a seventh filter unit 310, an eighth filter unit 320, and a ninth filter unit 330. Each of the seventh to ninth filter units 310, 320, and 330 of the third filter bank 300 includes a first Bragg reflector layer 351, a second Bragg reflector layer 352, and cavities 361, 362, and 363 between the first and second Bragg reflector layers 351 and 352. Each of the seventh cavity 361, the eighth cavity 362, and the ninth cavity 363 may include a dielectric material with a specific refractive index. For example, each of the seventh cavity 361, the eighth cavity 362, and the ninth cavity 363 may include silicon, silicon oxide, or titanium oxide.

[0165] The seventh filter unit 310, the eighth filter unit 320, and the ninth filter unit 330 may include seventh to ninth chambers 361, 362, and 363 with different thicknesses. For example, the thickness of the seventh chamber 361 may be less than the thickness of the eighth chamber 362, and the thickness of the ninth chamber 363 may be greater than the thickness of the eighth chamber 362. Therefore, the seventh to ninth filter units 310, 320, and 330 may have different center wavelengths. The third filter group 300, including the seventh to ninth filter units 310, 320, and 330, may have a center wavelength in a band between the first and second bands. Furthermore, the seventh to ninth filter units 310, 320, and 330 may have seventh to ninth chambers with different effective refractive indices.

[0166] Figure 30 It shows Figure 29 Example of the transmission spectrum of optical filter 1200.

[0167] exist Figure 30 In the diagram, "A" represents the transmission spectrum of the first filter group 100, "B" represents the transmission spectrum of the second filter group 200, and "C" represents the transmission spectrum of the third filter group 300.

[0168] Reference Figure 30 The third filter group 300 can realize the center wavelength within the band between the first band of the first filter group 100 and the second band of the second filter group 200.

[0169] Figure 31 This is a cross-sectional view of an optical filter 1300 according to another example embodiment.

[0170] Reference Figure 31The optical filter 1300 may include a first filter group 1310 and a second filter group 1320 arranged on the same plane. Each of the first filter group 1310 and the second filter group 1320 may include one or more filter units. Figure 31 An example is shown in which, for ease of description, each of the first filter group 1310 and the second filter group 1320 includes a filter unit, such as the first filter unit 1310a or the second filter unit 1320a. When each of the first filter group 1310 and the second filter group 1320 includes multiple filter units, the multiple filter units may include chambers having different thicknesses from each other.

[0171] The first filter unit 1310a includes a first bandpass filter 1311 and a first multilayer 1312 disposed on the first bandpass filter 1311. Here, the first filter unit 1310a can be connected with... Figure 2 The first to third filter units 110a, 120a and 130a shown are identical, and therefore their description is omitted. The first filter unit 1310a may have a center wavelength in the short band.

[0172] The second filter unit 1320a includes a second multilayer 1321 and a second bandpass filter 1325 on the second multilayer 1321. Here, the second multilayer 1321 can be connected to... Figure 2 The second multilayer 200b shown is the same, and therefore its description is omitted.

[0173] The second bandpass filter 1325 may have a cavity structure with a center wavelength in the long wavelength band and may include a material capable of absorbing short wavelength light. Short wavelengths are shorter than long wavelengths. The second bandpass filter 1325 may include two Bragg reflector layers 1322 and a cavity 1323 between the Bragg reflector layers 1322.

[0174] Each of the Bragg reflector layers 1322 may have a structure in which a first material layer 1322a and a second material layer 1322b having different refractive indices are alternately stacked. Here, one of the first material layer 1322a and the second material layer 1322b may include a material (e.g., silicon, GaP, etc.) capable of absorbing light in a first wavelength band (e.g., short-wavelength light). For example, the first material layer 1322a and the second material layer 1322b may include silicon and silicon oxide. For example, the first material layer 1322a may include silicon, and the second material layer 1322b may include silicon oxide. The cavity 1323 between the Bragg reflector layers 1322 may include, for example, silicon.

[0175] Figure 32 It shows Figure 31A diagram showing an example of the transmission spectrum of the first filter unit 1310a. (Refer to...) Figure 32 The first filter unit 1310a transmits the center wavelength in the shortwave band.

[0176] Figure 33 It shows Figure 31 A diagram illustrating an example of the transmission spectrum of the second filter unit 1320a. Here, the first material layer 1322a and the second material layer 1322b comprise silicon and silicon oxide, and the chamber 1323 comprises silicon. (Refer to...) Figure 33 Since silicon absorbs short-wavelength light, the second filter unit 1320a can transmit only the center wavelength of the long-wavelength band.

[0177] In the above description, the second multilayer 1321 is positioned below the second bandpass filter 1325, but the second multilayer 1321 can be omitted.

[0178] Figure 34 This is a cross-sectional view of an optical filter 1400 according to another example embodiment. In addition to the second bandpass filter 1425, Figure 34 Optical filter 1400 and Figure 31 The optical filter is the same as the 1300.

[0179] The first filter unit 1410 includes a first bandpass filter 1411 and a first multilayer 1412 on the first bandpass filter 1411. The first filter unit 1410 may have a center wavelength in the short band. The second filter unit 1420 includes a second multilayer 1421 and a second bandpass filter 1425 on the second multilayer 1421.

[0180] The second bandpass filter 1425 may have a cavity structure with a center wavelength in the long wavelength band and may include a material capable of absorbing short wavelength light. The second bandpass filter 1425 may include a Bragg reflector layer 1422, a cavity 1423, and a short wavelength absorption layer 1424.

[0181] The Bragg reflector layer 1422 may have a structure in which a first material layer 1422a and a second material layer 1422b having different refractive indices are alternately stacked. For example, the first material layer 1422a and the second material layer 1422b may comprise silicon oxide and titanium oxide. The Bragg reflector layer 1422 may include a cavity 1423. The cavity 1423 may comprise, for example, silicon. The cavity 1423 may include a short-wavelength absorption layer 1424. Here, the short-wavelength absorption layer 1424 may comprise, for example, silicon or GaP.

[0182] Figure 35 This is a cross-sectional view of an optical filter 1500 according to another example embodiment.

[0183] Reference Figure 35 The optical filter 1500 may include a first filter group 1510, a second filter group 1520, and a third filter group 1530 arranged on the same plane. Each of the first filter group to the third filter group 1510, 1520, and 1530 may include one or more filter units. Figure 35 An example is shown in which each of the first to third filter groups 1510, 1520, and 1530 includes a filter unit, such as the first filter unit 1510a, the second filter unit 1520a, or the third filter unit 1530a. When each of the first to third filter groups 1510, 1520, and 1530 includes multiple filter units, the multiple filter units may include chambers having different thicknesses from each other.

[0184] Each of the first filter unit 1510a, the second filter unit 1520a, and the third filter unit 1530a may have a structure in which the first material layer 1511a and the second material layer 1511b are alternately stacked, and the first material layer 1511a and the second material layer 1511b have a orientation in one direction (e.g., Figure 35 The optical thickness gradually increases in the upward direction. For example, the first material layer 1511a and the second material layer 1511b may have an optical thickness (FWOT) that gradually increases from about 0.15 to about 0.35 in the upward direction.

[0185] Each of the first to third filter units 1510a, 1520a, and 1530a may include a first chamber 1561, a second chamber 1562, and a third chamber 1563 between the first material layer 1511a and the second material layer 1511b. Here, the first to third chambers 1561, 1562, and 1563 may be located at different positions between the first material layer 1511a and the second material layer 1511b. Figure 36 It shows Figure 35 Example of the transmission spectrum of optical filter 1500.

[0186] Figure 37 This is a cross-sectional view of an optical filter 2000 according to another example embodiment.

[0187] Reference Figure 37 The optical filter 2000 includes filter units 110, 120, 130, 210, 220 and 230, and additional filters 2500 on the first to sixth filter units 110, 120, 130, 210, 220 and 230.

[0188] The additional filter 2500 may include multiple additional filter units, such as a first additional filter unit 2501, a second additional filter unit 2502, and a third additional filter unit 2503. The first additional filter unit 2501 corresponds to the first filter unit 110 and the second filter unit 120, the second additional filter unit 2502 corresponds to the third filter unit 130 and the fourth filter unit 210, and the third filter unit 2503 corresponds to the fifth filter unit 220 and the sixth filter unit 230. However, one or more example embodiments are not limited thereto, and each of the first to third additional filter units 2501, 2502, and 2503 may correspond to one filter unit or three or more filter units.

[0189] When the first filter unit 110 and the second filter unit 120 transmit the first wavelength band, the first additional filter unit 2501 can block light of other wavelength bands besides the desired first wavelength band of the first filter unit 110 and the second filter unit 120. For example, when the first filter unit 110 and the second filter unit 120 transmit a wavelength band of about 400 nm to about 500 nm, the first additional filter unit 2501 can be a blue filter unit that transmits blue light.

[0190] When the third filter unit 130 and the fourth filter unit 210 transmit the second wavelength band, the second additional filter unit 2502 can block light of other wavelength bands besides the second wavelength band desired by the third filter unit 130 and the fourth filter unit 210. For example, when the third filter unit 130 and the fourth filter unit 210 transmit a wavelength band of about 500 nm to about 600 nm, the second additional filter unit 2502 can be a green filter unit that transmits green light.

[0191] When the fifth filter unit 220 and the sixth filter unit 230 transmit the third wavelength band, the third additional filter unit 2503 can block light of other wavelength bands besides the desired third wavelength band of the fifth filter unit 220 and the sixth filter unit 230. For example, when the fifth filter unit 220 and the sixth filter unit 230 transmit a wavelength band of about 600 nm to about 700 nm, the third additional filter unit 2503 can be a red filter unit that transmits red light.

[0192] The additional filter 2500 may include a color filter. In this case, the first to third additional filter units 2501, 2502, and 2503 may be a first color filter unit, a second color filter unit, and a third color filter unit, respectively. The color filter may include, for example, a color filter commonly used in color display devices such as liquid crystal display devices or organic light-emitting display devices.

[0193] The additional filter 2500 may include a broadband filter. In this case, the first to third additional filter units 2501, 2502, and 2503 may be a first broadband filter unit, a second broadband filter unit, and a third broadband filter unit, respectively. Each of the broadband filter units may have, for example, a multi-chamber structure or a metal mirror structure.

[0194] Figure 38 It shows that it can be used as Figure 37 A diagram showing an example of a broadband filter with an additional filter of 2500. Figure 38 A broadband filter unit 2510 included in a broadband filter is shown.

[0195] Reference Figure 38 The broadband filter unit 2510 may include multiple reflective layers 2513, 2514 and 2515, and multiple chambers 2511 and 2512 between the reflective layers 2513, 2514 and 2515. Figure 38 Three reflective layers 2513, 2514 and 2515 and two chambers 2511 and 2512 are shown as examples, but one or more embodiments are not limited thereto, and the number of reflective layers 2513, 2514 and 2515 and the number of chambers 2511 and 2512 may vary.

[0196] The first reflective layer 2513, the second reflective layer 2514, and the third reflective layer 2515 are spaced apart from each other, the first chamber 2511 is between the first reflective layer 2513 and the second reflective layer 2514, and the second chamber 2512 is between the second reflective layer 2514 and the third reflective layer 2515.

[0197] Each of the first chamber 2511 and the second chamber 2512 may include a material having a specific refractive index. Additionally, each of the first chamber 2511 and the second chamber 2512 may include two or more materials having refractive indices different from each other.

[0198] Each of the first to third reflective layers 2513, 2514 and 2515 can be a Bragg reflective layer. Each of the first to third reflective layers 2513, 2514 and 2515 can have a structure in which multiple material layers having different refractive indices are stacked alternately.

[0199] Figure 39 It shows that it can be used as Figure 37 A diagram of another example of a broadband filter with an additional filter of 2500. Figure 39 A broadband filter unit 2520 included in a broadband filter is shown.

[0200] Reference Figure 39 The broadband filter unit 2520 may include a first metal mirror layer 2522 and a second metal mirror layer 2523, as well as a cavity 2521 between the first metal mirror layer 2522 and the second metal mirror layer 2523.

[0201] Figure 40 This is a cross-sectional view of an optical filter 3000 according to another example embodiment.

[0202] Reference Figure 40 The optical filter 300 includes multiple filter units 110, 120, 130, 210, 220, and 230, and short-wavelength absorption filters 1610 and long-wavelength blocking filters 1620 on the multiple filter units 110, 120, 130, 210, 220, and 230. According to... Figure 40 As shown, for ease of description, the first filter unit 110, the second filter unit 120 and the third filter unit 130 of the first filter group 100, and the fourth filter unit 210, the fifth filter unit 220 and the sixth filter unit 230 of the second filter group 200 are described as above, however, this disclosure is not limited thereto.

[0203] A short-wavelength absorption filter 1610 is disposed on some (110, 130 and 220) of the first filter units to the sixth filter units 110, 120, 130, 210, 220 and 230, and a long-wavelength absorption filter 1620 may be disposed on other (120, 210 and 230) of the first filter units to the sixth filter units 110, 120, 130, 210, 220 and 230. Figure 40 An example is shown in which each of the short-wavelength absorption filter 1610 and the long-wavelength blocking filter 1620 corresponds to one of filter units 110, 120, 130, 210, 220 and 230, but one or more embodiments are not limited thereto, and each of the short-wavelength absorption filter 1610 and the long-wavelength blocking filter 1620 may correspond to two or more of filter units 110, 120, 130, 210, 220 and 230.

[0204] The short-wavelength absorption filter 1610 can block short-wavelength light, such as visible light. The short-wavelength absorption filter 1610 can be fabricated by depositing a material (e.g., silicon) capable of absorbing visible light on some of the filter units 110, 120, 130, 210, 220, and 230 (110, 130, and 220). Filter units 110, 130, and 220 with the short-wavelength absorption filter 1610 can transmit near-infrared (NIR) light with wavelengths longer than visible light.

[0205] The long-wavelength blocking filter 1620 can block long-wavelength light such as NIR. The long-wavelength blocking filter 1620 may include an NIR cutoff filter. Filter units 120, 210, and 230 equipped with the long-wavelength blocking filter 1620 can transmit visible light with wavelengths shorter than NIR wavelengths.

[0206] According to the example embodiment, a short-wavelength absorption filter 1610 and a long-wavelength blocking filter 1620 are disposed on filter units 110, 120, 130, 210, 220 and 230, so that a broadband (i.e., from the visible light band to the NIR band) filter 300 can be manufactured.

[0207] According to exemplary embodiments of this disclosure, the optical filter includes multiple filter units capable of filtering different wavelength bands, thus improving broadband characteristics. Furthermore, since each of the multiple filter units includes multiple layers capable of blocking light of undesirable wavelength bands, desired wavelength bands can be achieved, and spectral characteristics can be improved. Although exemplary embodiments have been described above, these are merely illustrative, and various modifications can be made thereto by those skilled in the art.

[0208] It should be understood that the exemplary embodiments described herein should be considered descriptive only and not for limiting purposes. The description of features or aspects in each exemplary embodiment should typically be interpreted as other similar features or aspects that may be used in other exemplary embodiments. Although one or more exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. An optical filter, comprising: At least one first filter element; as well as At least one second filter element is arranged on the same plane as the at least one first filter element. Each of the at least one first filter element includes: A first bandpass filter, having a first center wavelength within a first band, and comprising a plurality of first Bragg reflectors and at least one first chamber disposed between the plurality of first Bragg reflectors; and A first multilayer layer is disposed on the first bandpass filter, the center wavelength of the first multilayer layer being different from the first center wavelength of the first bandpass filter, so as to block light of other wavelengths besides the first band. Each of the at least one second filter element includes: A second bandpass filter, having a second center wavelength within a second band, and comprising a plurality of second Bragg reflectors and at least one second chamber disposed between the plurality of second Bragg reflectors; and A second multilayer layer is disposed below the second bandpass filter, the center wavelength of the second multilayer layer being different from the second center wavelength of the second bandpass filter, so as to block light of other bands besides the second band.

2. The optical filter according to claim 1, wherein, Each of the plurality of first Bragg reflector layers and the first multilayer has a structure in which a plurality of material layers having different refractive indices are alternately stacked. Wherein, each of the plurality of material layers in the first multilayer has a first thickness and is made of a first material, and Wherein, at least one of the first thickness or the first material is different from the second thickness or the second material of each of the plurality of material layers of the plurality of first Bragg reflector layers.

3. The optical filter according to claim 2, wherein, The first multilayer includes a third Bragg reflector layer, which comprises a material layer having the same optical thickness.

4. The optical filter according to claim 2, wherein, The first multilayer includes a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

5. The optical filter according to claim 4, wherein, The first pass filter includes a shortwave pass filter.

6. The optical filter according to claim 2, wherein, The first center wavelength of the first bandpass filter is adjusted by changing the thickness or effective refractive index of the at least one first chamber.

7. The optical filter according to claim 1, wherein, Each of the plurality of second Bragg reflector layers and the second multilayer has a structure in which a plurality of material layers having different refractive indices are alternately stacked. Wherein, the plurality of material layers in the second multilayer have a third thickness and are made of a third material, and Wherein, at least one of the third thickness or the third material is different from the fourth thickness or the fourth material of each of the plurality of material layers of the plurality of second Bragg reflector layers.

8. The optical filter according to claim 7, wherein, The material layer in each of the plurality of second Bragg reflector layers is the same as the material layer in the first multilayer layer, and the material layer in the second multilayer layer is the same as the material layer in each of the plurality of first Bragg reflector layers.

9. The optical filter according to claim 7, wherein, The second multilayer includes a fourth Bragg reflector layer, which comprises a material layer having the same optical thickness.

10. The optical filter according to claim 7, wherein, The second multilayer includes a second pass filter, which includes material layers, at least some of which have different optical thicknesses.

11. The optical filter according to claim 10, wherein, The second pass filter includes a long-wave pass filter.

12. The optical filter according to claim 1, wherein, The second center wavelength of the second bandpass filter is adjusted by changing the thickness or effective refractive index of the second chamber.

13. The optical filter of claim 1, wherein the plurality of second Bragg reflector layers comprises a material that absorbs light in the first wavelength band.

14. The optical filter of claim 1, further comprising at least one third filter element, said at least one third filter element being arranged on the same plane as said at least one first filter element and said at least one second filter element, wherein, The at least one third filter element has a third center wavelength between the first band and the second band.

15. The optical filter according to claim 1, further comprising: An additional filter is provided on the at least one first filter element and the at least one second filter element to transmit only a specific wavelength band.

16. The optical filter according to claim 15, wherein, The additional filters include color filters or broadband filters.

17. The optical filter according to claim 1, wherein, A short-wavelength absorption filter is provided on some of the at least one first filter element and the at least one second filter element, and a long-wavelength blocking filter is provided on some of the other at least one first filter element and the at least one second filter element.

18. A spectrometer, comprising: Optical filters; as well as The sensing device receives light transmitted through the optical filter; The optical filter includes: at least one first filter element; and at least one second filter element arranged on the same plane as the at least one first filter element. Each of the at least one first filter element comprises: a first bandpass filter having a first center wavelength within a first band, and including a plurality of first Bragg reflector layers and at least one first chamber disposed between the plurality of first Bragg reflector layers; and a first multilayer disposed on the first bandpass filter, the center wavelength of the first multilayer being different from the first center wavelength of the first bandpass filter, so as to block light of other bands besides the first band. Each of the at least one second filter element includes: a second bandpass filter having a second center wavelength within a second band and including a plurality of second Bragg reflector layers and at least one second chamber disposed between the plurality of second Bragg reflector layers; and a second multilayer disposed below the second bandpass filter, the center wavelength of the second multilayer being different from the second center wavelength of the second bandpass filter to block light of other bands besides the second band.

19. The spectrometer according to claim 18, wherein, Each of the plurality of first Bragg reflector layers and the first multilayer has a structure in which a plurality of material layers having different refractive indices are alternately stacked. Wherein, each of the plurality of material layers in the first multilayer has a first thickness and is made of a first material, and Wherein, at least one of the first thickness or the first material is different from the second thickness or the second material of each of the plurality of material layers of the plurality of first Bragg reflector layers.

20. The spectrometer according to claim 19, wherein, The first multilayer includes a third Bragg reflector layer, which comprises a material layer having the same optical thickness.

21. The spectrometer according to claim 19, wherein, The first multilayer includes a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

22. The spectrometer according to claim 19, wherein, The first center wavelength of the first bandpass filter is adjusted by changing the thickness or effective refractive index of the at least one first chamber.

23. The spectrometer according to claim 18, wherein, Each of the plurality of second Bragg reflector layers and the second multilayer has a structure in which a plurality of material layers having different refractive indices are alternately stacked. Wherein, the plurality of material layers in the second multilayer have a third thickness and are made of a third material, and Wherein, at least one of the third thickness or the third material is different from the fourth thickness or the fourth material of each of the plurality of material layers of the plurality of second Bragg reflector layers.

24. The spectrometer according to claim 23, wherein, The second multilayer includes a fourth Bragg reflector layer, which comprises a material layer having the same optical thickness.

25. The spectrometer according to claim 23, wherein, The second multilayer includes a first pass filter, which includes material layers, at least some of which have different optical thicknesses.

26. The spectrometer according to claim 23, wherein, The second center wavelength of the second bandpass filter is adjusted by changing the thickness or effective refractive index of the second chamber.

27. The spectrometer of claim 18, wherein the plurality of second Bragg reflector layers comprise a material that absorbs light in the first wavelength band.

28. The spectrometer according to claim 18, wherein, The optical filter further includes: at least one third filter element, arranged on the same plane as the at least one first filter element and the at least one second filter element, and The at least one third filter element has a third center wavelength between the first band and the second band.

29. The spectrometer according to claim 18, wherein, The optical filter further includes an additional filter disposed on the at least one first filter element and the at least one second filter element to transmit only a specific wavelength band.

30. The spectrometer according to claim 18, wherein, A short-wavelength absorption filter is provided on some of the at least one first filter element and the at least one second filter element, and a long-wavelength blocking filter is provided on some of the other at least one first filter element and the at least one second filter element.

31. An optical filter, comprising: The first filter bank includes: Multiple first bandpass filters; and Multiple first multilayers disposed on the plurality of first bandpass filters; and A second filter bank, arranged on the same plane as the first filter bank, includes: Multiple second bandpass filters; and Multiple second multilayers are disposed below the plurality of second bandpass filters. The plurality of first bandpass filters include: A bandpass filter having a first center wavelength within a first band, comprising a plurality of first Bragg reflectors and at least one first chamber disposed between the plurality of first Bragg reflectors, and A bandpass filter having a second center wavelength within a first band includes a plurality of second Bragg reflectors and at least one second chamber disposed between the plurality of second Bragg reflectors. The plurality of first multilayers are configured to block light of a different wavelength than the first band. The plurality of second bandpass filters include: A bandpass filter having a third center wavelength within a second band, comprising a plurality of third Bragg reflectors and at least one third chamber disposed between the plurality of third Bragg reflectors, and A bandpass filter having a fourth center wavelength within a second band includes a plurality of fourth Bragg reflectors and at least one fourth chamber disposed between the plurality of fourth Bragg reflectors. The plurality of second multilayers are configured to block light of a different wavelength than the second band.

Images