Optical filter

Abstract

The filter may include a set of filter layers disposed on a substrate. The set of filter layers may include a first subset of filter layers including a first material having a first refractive index. The first material may include at least silicon and hydrogen. The set of filter layers may include a second subset of filter layers including a second material having a second refractive index. The second material is different from the first material and the second refractive index is less than the first refractive index. The set of filter layers may include a third subset of filter layers including a third material different from the first material and the second material.

Description

[0001] This case is a divisional application of the patent application with application number 201980086494.0 and title “Optical Filter” filed by the present applicant on December 23, 2019. The entire contents of the parent case are incorporated into this divisional application by reference. Technical Field

[0002] This application claims the benefit of U.S. Non-Provisional Patent Application No. 16 / 722,325, filed on December 20, 2019, entitled “Optical Filter,” and U.S. Provisional Patent Application No. 62 / 785,487, filed on December 27, 2018, entitled “Optical Filter,” which are expressly incorporated herein by reference. Background Art

[0003] The optical transmitter can emit light directed toward one or more objects. For example, in a gesture recognition system, the optical transmitter can emit near infrared (NIR) light toward the user, and the NIR light can be reflected by the user toward the optical receiver. In this case, the optical receiver can capture information about the NIR light, and the information can be used to recognize the gesture being performed by the user. For example, the device can use the information to generate a three-dimensional representation of the user and recognize the gesture being performed by the user based on the three-dimensional representation.

[0004] Ambient light may interfere with the NIR light during transmission toward the user and / or during reflection from the user toward the optical receiver. Therefore, the optical receiver may be optically coupled to an optical filter, such as a bandpass filter, to filter the ambient light and allow the NIR light to pass toward the optical receiver. Summary of the invention

[0005] According to some embodiments, the filter may include a group of filter layers, the group of filter layers including: a first subset of filter layers, which includes a first material with a first refractive index, the first material including at least silicon and hydrogen; a second subset of filter layers, which includes a second material with a second refractive index, the second material is different from the first material and the second refractive index is less than the first refractive index; and a third subset of filter layers, which includes a third material different from the first material and the second material.

[0006] According to some embodiments, the filter may include: a substrate; one or more high refractive index material layers and one or more low refractive index material layers disposed on the substrate to filter incident light, wherein a first portion of the incident light having a first spectral range will be reflected by the filter, and a second portion of the incident light having a second spectral range will be passed by the filter, the one or more high refractive index material layers are a first material, and the one or more low refractive index material layers are a second material; and one or more transition material layers disposed on the substrate, the one or more transition material layers being a third material different from the first material and the second material.

[0007] According to some embodiments, an optical system may include: an optical transmitter that emits near-infrared (NIR) light; an optical filter that filters an input optical signal and provides a filtered input optical signal, the input optical signal including NIR light from the optical transmitter and ambient light from the light source, the optical filter including a set of dielectric thin film layers, the set of dielectric thin film layers including: a first subset layer formed of a first material having a first refractive index, a second subset layer formed of a second material having a second refractive index less than the first refractive index, a third subset layer formed of a third material different from the first material and the second material, and a fourth subset layer formed of a fourth material different from the first material, the second material, and the third material; a filtered input optical signal including ambient light having a reduced intensity relative to the input optical signal; and an optical receiver that receives the filtered input optical signal and provides an output electrical signal.

[0008] According to some embodiments, a method of manufacturing a filter may include: depositing a first subset filter layer of the filter, the first subset filter layer comprising a first material having a first refractive index; depositing a second subset filter layer of the filter, the second subset filter layer comprising a second material having a second refractive index less than the first refractive index; and depositing a third subset filter layer comprising a third material different from the first material and the second material.

[0009] The present invention also includes the following items:

[0010] 1. A filter comprising:

[0011] A set of filter layers,

[0012] The set of filter layers includes:

[0013] a first subset of filter layers comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen;

[0014] a second subset of filter layers comprising a second material having a second refractive index,

[0015] The second material is different from the first material and has a second refractive index less than the first refractive index; and

[0016] The third subset of filter layers includes a third material different from the first material and the second material.

[0017] 2. The optical filter according to item 1, wherein the first material comprises at least one of the following:

[0018] Silicon hydride (Si:H) materials,

[0019] Silicon Germanium (SiGe) material, or

[0020] Hydrogenated silicon germanium (SiGe:H) material.

[0021] 3. The optical filter according to item 1, wherein the second material comprises at least one of the following:

[0022] Silicon dioxide (SiO 2 )Material,

[0023] Alumina (Al 2 O 3 )Material,

[0024] Titanium dioxide (TiO 2 )Material,

[0025] Niobium pentoxide (Nb 2 O 5 )Material,

[0026] Tantalum pentoxide (Ta 2 O 5 )Material,

[0027] Magnesium fluoride (MgF 2 )Material,

[0028] Zirconia (ZrO 2 )Material,

[0029] Yttrium oxide (Y 2 O 3 )Material,

[0030] Silicon Nitride (Si 3 N 4 )Material,

[0031] Boron-based materials, or

[0032] Phosphorus-based materials.

[0033] 4. The optical filter according to item 1, further comprising:

[0034] A fourth subset of filter layers includes a fourth material different from at least the first material and the second material.

[0035] 5. The optical filter according to item 1, further comprising:

[0036] A substrate is provided with the set of filter layers thereon.

[0037] 6. The optical filter according to item 5, wherein the set of filter layers is arranged on the first side of the substrate, and

[0038] The coating is disposed on the second surface of the substrate.

[0039] 7. The optical filter according to item 1, wherein the first refractive index is greater than 3 in the spectral range from about 800 nm to about 1100 nm.

[0040] 8. The optical filter according to item 1, wherein the first refractive index is approximately 3.7 at a wavelength of about 800 nm to about 1100 nm.

[0041] 9. The optical filter according to item 1, wherein the second refractive index is less than 3 in the spectral range from about 800 nm to about 1100 nm.

[0042] 10. The optical filter according to item 1, wherein the second refractive index is between 1.6 and 2.4 in the spectral range of about 800 nm to about 1100 nm.

[0043] 11. The optical filter according to item 1, wherein the optical filter is a bandpass filter.

[0044] 12. The optical filter according to item 1, wherein the optical filter is annealed.

[0045] 13. An optical system comprising:

[0046] an optical emitter that emits near infrared (NIR) light;

[0047] an optical filter that filters an input optical signal and provides a filtered input optical signal, the input optical signal comprising near infrared light from the optical emitter and ambient light from a light source,

[0048] The optical filter comprises a set of dielectric thin film layers, the set of dielectric thin film layers comprising:

[0049] a first subset of layers formed of a first material having a first refractive index,

[0050] a second subset of layers formed of a second material having a second refractive index less than the first refractive index,

[0051] a third subset of layers formed of a third material different from the first material and the second material, and

[0052] a fourth subset of layers formed of a fourth material different from the first material, the second material, and the third material;

[0053] The filtered input light signal comprises ambient light with reduced intensity relative to the input light signal; and

[0054] An optical receiver receives the filtered input optical signal and provides an output electrical signal.

[0055] 14. An optical system according to item 13, wherein the filter is associated with a transmittance greater than 80% at about 950 nm.

[0056] 15. The optical system of item 13, wherein the filter is associated with a transmittance greater than 90% at approximately 950 nm.

[0057] 16. The optical system of item 13, wherein the filter is associated with a transmittance greater than 80% at approximately 1550 nm.

[0058] 17. The optical system of item 13, wherein the filter is associated with a transmittance greater than 90% at approximately 1550 nm.

[0059] 18. An optical system according to item 13, wherein the first subset of layers is hydrogenated.

[0060] 19. A method for manufacturing an optical filter, comprising:

[0061] depositing a first subset of filter layers of said filter,

[0062] The first subset of filter layers comprises a first material having a first refractive index;

[0063] depositing a second subset of filter layers of said filter,

[0064] The second subset of filter layers comprises a second material having a second refractive index less than the first refractive index; and

[0065] A third subset of filter layers is deposited comprising a third material different from the first material and the second material.

[0066] 20. The method of clause 19, wherein one or more of the first subset of filter layers, the second subset of filter layers, or the third subset of filter layers are deposited by direct current sputtering. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figures 1A-1C is a diagram of one or more exemplary embodiments described herein.

[0068] Figures 2A-2D is a graph of one or more examples of optical and / or mechanical properties of a set of materials related to one or more example embodiments described herein.

[0069] Figures 3A-3D is a diagram of one or more examples of a sputter deposition system for making one or more exemplary embodiments described herein.

[0070] Figures 4A-4Bis a graph of one or more examples of optical properties of a set of materials related to one or more example embodiments described herein.

[0071] Figure 5A is a graph of one or more examples of mechanical properties of a set of materials related to one or more embodiments described herein.

[0072] Figure 5B is a graph of one or more examples of optical properties of a set of materials related to one or more example embodiments described herein.

[0073] Figure 6A-6B is a graph of one or more examples of optical properties of a set of materials related to one or more example embodiments described herein.

[0074] Figure 6C is a graph of one or more examples of mechanical properties of a set of materials associated with one or more exemplary embodiments described herein.

[0075] Figure 7A-7B is a diagram of one or more exemplary embodiments described herein.

[0076] Fig. 8A is a graph showing an example of the refractive index of a hydrogenated silicon layer.

[0077] Figure 8B is a graph showing an example of the extinction coefficient of a hydrogenated silicon layer.

[0078] Fig. 9 is a graph of examples of transmission spectra of the filters described herein. DETAILED DESCRIPTION

[0079] The following detailed description of exemplary embodiments refers to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements. U.S. Patent Application Publication No. 20170336544 to Hendrix et al., published on November 23, 2017, is incorporated herein by reference.

[0080] The optical receiver can receive light from a light source such as an optical transmitter. For example, the optical receiver can receive near infrared (NIR) light reflected from the optical transmitter and back from a target. The target can include people (e.g., users and non-users), animals, inanimate objects (e.g., cars, trees, obstacles, furniture, walls), etc. In this case, the optical receiver can receive NIR light as well as ambient light, such as visible spectrum light. The ambient light can include light from one or more light sources separated from the optical transmitter, such as sunlight, light from a light bulb, etc. The ambient light may reduce the accuracy of the determination related to the NIR light. For example, in a gesture recognition system, the ambient light may reduce the accuracy of generating a three-dimensional image of the target based on the NIR light. In some examples, information about the NIR light can be used to identify the identity of the user, the characteristics of the user (e.g., height or weight), the state of the user (e.g., the position of the user's eyelids, whether the user is awake, etc.), characteristics of another type of target (e.g., distance to the object, size of the object, or shape of the object), etc. Therefore, the optical receiver can be optically coupled to a filter such as a bandpass filter to filter the ambient light and pass the NIR light toward the optical receiver.

[0081] For example, the filter may include a set of dielectric film layers that may be selected and deposited to block a portion of out-of-band light below a certain threshold (e.g., 700 nm) and pass light of a certain range of wavelengths, such as a range of about 700 nm to about 1700 nm, a range of about 800 nm to about 1100 nm, a range of about 900 nm to about 1000 nm, a range of about 920 nm to about 980 nm, etc. In some examples, the passband may have a center wavelength in the range of 800 nm to 1100 nm, a range of about 820 nm to about 880 nm, a range of about 920 nm to 980 nm, a range of about 870 nm to 930 nm, etc. In another example, the set of dielectric film layers may be selected to filter out ambient light. Additionally or alternatively, the set of dielectric film layers may be selected to block out-of-band light below a certain threshold and pass light of another wavelength range, such as a range of about 1500 nm to about 1600 nm, a range of about 1520 nm to about 1580 nm, or a center wavelength of about 1550 nm.

[0082] Some embodiments described herein may utilize materials including silicon and hydrogen, hydrogenated silicon (Si:H) based materials, silicon germanium (SiGe) based materials, hydrogenated silicon germanium (SiGe:H) materials, etc. in a set of high refractive index layers for filters, such as low angle shift filters. The materials in the high refractive index layer group may include at least silicon (Si) and hydrogen (H), any isotopes of silicon and H (e.g., protium (A=1), deuterium (A=2), tritium (A)=3)), and / or any mixture thereof. In this way, a filter based on a set of high refractive index layers with a higher effective refractive index can provide a relatively low angle shift relative to another filter stack using another high refractive index layer material. In addition, filters using any of these high refractive index layer materials can substantially block or effectively shield ambient light and allow NIR light to pass.

[0083] Figures 1A-1C are diagrams of example filters 100, 100', 100". Figures 1A-1C An example stackup of filters using three or more different materials is shown. Figures 1A-1C As further shown, the optical filter 100 , 100 ′, 100 ″ may include an optical filter coating portion 110 and a substrate 120 .

[0084] like Figures 1A-1C As shown, the filter coating portion 110 includes a group of filter layers. For example, the filter coating portion 110 includes a first group of layers 130, a second group of layers 140, and a third group of layers 135. The first group of layers 130 may include a group of high refractive index material layers, and may be referred to herein as H layers 130. For example, in some embodiments, the H layer 130 may include a material including hydrogen and silicon (e.g., a hydrogenated silicon (Si:H) layer, which may include silicon (Si) and hydrogen (H), any isotopes of Si and H (including protium (A=1), deuterium (A=2), and / or tritium (A=3)), a hydrogenated silicon germanium (SiGe:H) layer, etc.). In some embodiments, the H layer 130 may include a material including silicon and germanium (e.g., a silicon germanium (SiGe) layer, etc.).

[0085] These high refractive index materials may have a refractive index higher than 3, 3.2, 3.5, 3.6, 4, etc. in a range of at least 800nm ​​to 1100nm. For example, Si:H may have a refractive index greater than 3 in a wavelength range of 800nm ​​to 1100nm. In some embodiments, the Si:H material has a refractive index greater than 3.5 (e.g., a refractive index greater than 3.64) in a wavelength range of 800nm ​​to 1100nm. In some embodiments, the Si:H material may have a refractive index of about 3.8 at a wavelength of about 830nm. In some embodiments, the refractive index at 800nm ​​may be greater than 3.87. In some embodiments, the Si:H material has a refractive index less than 4.3 in a wavelength range of 800nm ​​to 1100nm. The high refractive index layer may include phosphorus, boron, nitride, argon, oxygen, carbide, etc.

[0086] In some embodiments, the second set of layers 140 may include a set of low refractive index material layers and may be referred to herein as L layers 140. For example, the refractive index of L layers 140 is generally lower than the refractive index of H layers 130. In some embodiments, L layers 140 may include silicon, magnesium, fluoride, oxygen, tantalum, nitride, niobium, titanium, aluminum, zirconium, yttrium, or a combination thereof. For example, L layers 140 may include silicon dioxide (SiO 2 ) layer, silicon nitride (Si 3 N 4 ) layer, magnesium fluoride (MgF 2 ) layer, tantalum pentoxide (Ta 2 O 5 ) layer, niobium pentoxide (Nb 2 O 5 ) layer, titanium dioxide (TiO 2 ) layer, aluminum oxide (Al 2 O 3 ) layer, zirconium oxide (ZrO 2 ) layer, yttrium oxide (Y 2 O 3 ) layers, their combinations, etc.

[0087] In some embodiments, the third group of layers 135 may correspond to transition layers and may be referred to herein as O-layers 135. In some embodiments, O-layers 135 may include a third material different from H-layers 130 and / or L-layers 140. O-layers 135 may be any material, including oxides. For example, the O-layers may include silicon, silicon oxide (in any concentration) (e.g., SiO x , where 0<x<2), silicon dioxide (SiO 2 ), their combinations, etc.

[0088] like Figure 1BAs shown, the filter coating portion 110 may include a fourth set of layers 145, which may correspond to the second set of transition layers referred to herein as P layers 145. In some embodiments, the P layers 145 may include a fourth material different from the H layers 130, the O layers 135, and the L layers 140. Alternatively, in some embodiments, the P layers 145 may be the same or similar material as the O layers 135. The P layers may be any material, including oxides. For example, the P layers 145 may include silicon, silicon oxide (in any concentration) (e.g., SiO x , where 0<x<2), silicon dioxide (SiO 2 ), combinations thereof, etc. In some embodiments, Figure 1A A repeating unit of HOL layers is shown, wherein an O layer 135 precedes each H layer 130 (when counting from the air interface toward the substrate 120). In contrast, Figure 1B shows a repeating unit of the HOL layer, wherein the P layer 145 is disposed between each HOL unit. For further comparison, Figure 1C A repeating unit of layer HL is shown, with an O layer disposed between each HL unit.

[0089] In some embodiments, the outermost layer (e.g., the layer closest to the air interface) can be a layer other than the L layer 140. For example, in some embodiments, the outermost layer can be the H layer 130, the O layer 135, or the P layer 145. In some embodiments, the functional layer and / or coating can be outside the filter coating portion 110. For example, in some embodiments, the functional layer and / or coating can include an anti-fouling coating, a protective coating, a durable coating, an anti-fog coating, a hydrophilic coating, and / or a hydrophobic coating. In one example, the outermost layer can be a nitride.

[0090] In some embodiments, the layers 130, 135, 140, and 145 may be stacked in a specific order, such as a (HOL)m order, a (HOLO)m order, a (HLO)m order, a (HOLP)m order, a (HOL)mH order, a (HOLP)mH order, a (HOLP)nHOL order, a L-(HOL)m order, a LP-(HOLP)m order, a combination thereof, another possible order, etc., where m is the number of units of the layer, and its value is greater than or equal to 1. For example, as Figure 1A As shown, the layers 130, 135 and 140 are positioned in the order of (HOL)m, wherein the L layer 140 is disposed on the surface of the filter 100 and the H layer 130 is disposed on the surface of the substrate 120. Figure 1BIn the example shown, the layers 130, 135, 140, and 145 are positioned in the order of (HOLP)m, wherein the L layer 140 is disposed on the surface of the filter 100', and the H layer 130 is disposed on the surface of the substrate 120. Figure 1C In the example shown, the layers 130 , 135 , and 140 are positioned in the order of (HLO)m, wherein the L layer 140 is disposed on the surface of the filter 100 ″ and the H layer 130 is disposed on the surface of the substrate 120 .

[0091] The number, thickness and / or order of layers can affect the optical quality of the filter coating portion 110 and / or the filter 100, 100', 100", including light transmission and angular shift. In some embodiments, the filter coating portion 110 can be associated with a specific number of layers m. For example, the filter coating portion 110 can include 2 to 200 layers, 10 to 100 layers, or 30 to 60 layers. The filter coating portion 110 can include 10 to 40 H layers 130. In some examples, SiGe:H-based filters can include a range of 2 layers to 200 layers.

[0092] In some embodiments, each layer of filter coating portion 110 can be associated with a particular thickness. For example, layers 130 and 140 can each be associated with a thickness between 1 nm and 1500 nm, 3 nm and 1000 nm, 6 nm and 1000 nm, or 10 nm and 500 nm, and / or filter coating portion 110 can be associated with a thickness between 0.1 μm and 100 μm, between 0.25 μm and 20 μm, etc. In some examples, at least one of layers 130 and 140 can be associated with a thickness of less than 1000 nm, less than 600 nm, less than 100 nm, or less than 20 nm, and / or filter coating portion 110 can be associated with a thickness of less than 100 μm, less than 50 μm, and / or less than 10 μm. In some embodiments, layers 130 and 140 can be associated with multiple thicknesses, such as a first thickness for layer 130 and a second thickness for layer 140, a first thickness for a first subset of layers 130 and a second thickness for a second subset of layers 130, a first thickness for a first subset of layers 140 and a second thickness for a second subset of layers 140, etc. In such cases, the layer thicknesses and / or number of layers can be selected based on a desired set of optical properties, such as a desired passband, a desired reflectivity, etc.

[0093] Layers 135 and 145 may each be associated with a thickness between 1 nm and 20 nm. Depending on the manufacturing method and / or the desired optical quality of the filter coating portion 110 and / or the filter 100, 100', 100", the O layer 135 and the P layer 145 can each be associated with a thickness of less than 10 nm. In some examples, the O layer 135 and the P layer 145 can each be associated with a thickness of 1 nm to 10 nm, or 2 nm to 6 nm, or about 5 nm. In some embodiments, the O layer 135 and the P layer 145 can each be associated with a thickness between 2 nm and 6 nm, or about 5 nm. In some embodiments, the O layer 135 and the P layer 145 can be associated with a plurality of thicknesses, such as a first thickness of the O layer 135 and a second thickness of the P layer 145, a first thickness of a first subset of the O layers 135, a second thickness of a second subset of the O layers 135, a first thickness of a first subset of the P layers 145, and a second thickness of a second subset of the P layers 145, etc. In this case, the layer thickness and / or the number of layers can be selected based on a desired set of optical properties, such as a desired passband, a desired reflectivity, etc.

[0094] In some embodiments, a specific SiGe-based material can be selected for the H layer 130. For example, in some embodiments, the H layer 130 can be selected and / or fabricated (e.g., via a sputtering process, as described in further detail below) to include a specific type of SiGe, such as SiGe-50, SiGe-40, SiGe-60, etc.

[0095] In some embodiments, as described herein, as a result of the sputtering deposition process, the H layer 130 can include another material, such as argon. In another example, the H layer 130 can be manufactured using a hydrogenation process to hydrogenate a silicon or SiGe-based material, a nitridation process to nitridate a silicon or SiGe-based material, one or more annealing processes to anneal a silicon or SiGe-based material, another type of process, a doping process (e.g., phosphorus-based doping, nitrogen-based doping, boron-based doping, etc.) to dope a silicon or SiGe-based material, or a combination of multiple processes (e.g., a combination of hydrogenation, nitridation, annealing, and / or doping), as described herein. For example, the H layer 130 can be selected to include a refractive index greater than the refractive index of the L layer 140, such as within a spectral range of about 800 nm to about 1100 nm, a spectral range of about 820 nm to about 1000 nm, a specific wavelength of about 950 nm, etc. In another example, the H layer 130 may be selected to include a refractive index greater than the refractive index of the L layer 140, for example, within a spectral range of about 1400 nm to about 1700 nm, a spectral range of about 1500 nm to about 1600 nm, a specific wavelength of about 1550 nm, etc. In this case, the H layer 130 may be associated with a refractive index greater than 3, a refractive index greater than 3.5, a refractive index greater than 3.8, or a refractive index greater than 4. For example, the H layer 130 may be associated with a refractive index greater than 4 at about 950 nm, where the H layer 130 includes SiGe:H, the H layer 130 may be associated with a refractive index of about 3.74 at about 950 nm, where the H layer includes Si:H, etc.

[0096] In some embodiments, a specific material may be selected for the L layer 140. For example, the L layer 140 may include a group of SiO 2 Layer, a group of Al 2 O 3 layer, a group of TiO 2 layer, a group of Nb 2 O 5 Layer, a group of Ta 2 O 5 layer, a group of MgF 2 Layer, a group of Si 3 N 4 layer, a group of ZrO 2 Layer, a group of Y 2 O 3 In this case, the L layer 140 may be selected to include a refractive index lower than that of the H layer 130 .

[0097] In some embodiments, the H layer 130 and / or the L layer 140 can be associated with a specific extinction coefficient. For example, for an H layer 130 including silicon and hydrogen, the extinction coefficient can be less than about 0.001 in a specific spectral range. For example, the extinction coefficient can be less than about 0.001 in a spectral range of about 800 nm to about 1100 nm, a spectral range of about 900 nm to about 1000 nm, a wavelength of about 954 nm, etc. For an H layer 130 including germanium, such an extinction coefficient in a specific spectral range can be less than about 0.007 (0.004 for Si:H at 800 nm), less than about 0.003 (0.002 for Si:H at 800 nm), less than about 0.001, etc. For example, the extinction coefficient can be defined at a spectral range of about 800 nm to about 1100 nm, a spectral range of about 900 nm to about 1000 nm, a wavelength of about 954 nm, etc. Additionally or alternatively, the extinction coefficient may be defined at a spectral range of about 1400 nm to about 1700 nm, a spectral range of about 1500 nm to about 1600 nm, a specific wavelength of about 1550 nm, etc. In some embodiments, the specific material used for the L layer 140 may be selected based on the desired width of the out-of-band blocking spectral range, the desired center wavelength shift associated with changes in the angle of incidence (AOI), etc.

[0098] In some embodiments, the optical filter 100, 100', 100" may include a coating 180 on a side of the substrate opposite to the filter coating portion 110. The coating 180 may be a single layer or a multilayer. In some examples, the coating 180 may be an anti-reflective coating, a blocking filter, and / or a bandpass filter. The coating 180 may include at least one of an oxide, including SiO x 、SiO 2 、TiO 2 、 2 O 5 In one example, the coating 180 may be SiO 2 and TiO 2 Additionally or alternatively, coating 180 can have a similar structure to filter coating portion 110 and can include more than two materials. In some embodiments, coating 180 can include H layer 130, L layer 140, O layer 135, and / or P layer 145 of filter coating portion 110.

[0099] The filter coating portion 110 may be manufactured by any method, including but not limited to any coating and / or sputtering process. Figure 1AThe filter coating portion 110 shown can be manufactured by depositing an H layer 130 on a substrate 120 and then depositing an O layer 135 on the H layer 130. An L layer 140 can then be deposited on the O layer 135, and then a second H layer 130 can be deposited on the L layer 140. This can be repeated until the desired number of layers are deposited. Figure 1B The filter coating portion 110 shown can be manufactured by depositing an H layer 130 on a substrate 120 and then depositing an O layer 135 on the H layer 130. An L layer 140 can then be deposited on the O layer 135, and a P layer 145 can be deposited on the L layer 140. A second H layer 130 can then be deposited on the P layer 145. This can be repeated until the desired number of layers are deposited. Similarly, as Figure 1C The filter coating portion 110 shown can be made by depositing an H layer 130 on a substrate 120 and then depositing an L layer 140 on the H layer 130. An O layer 135 can then be deposited on the L layer 140, and then a second H layer 130 can be deposited on the O layer 135. This can be repeated until the desired number of layers are deposited. In some cases, other materials can be present on one or more of the layers 130, 135, 140, 145, etc. For example, during the deposition process, the material used to form the deposited layer can penetrate into the underlying layer.

[0100] In some embodiments, although a particular material may be deposited during the manufacturing process, the final composition of the filter coating portion 110 may be different from the deposited composition. For example, a first H layer 130 of Si:H may be deposited on the substrate 120. SiO 2 The first O layer 135 of Ta may be deposited on the first H layer 130 of Si:H. 2 O 5 The first L layer 140 may be deposited on SiO 2 The second H layer 130 of Si:H can be deposited on the Ta 2 O 5 On the first L layer 140. SiO 2 The second O layer 135 of Ta can be deposited on the second H layer 130 of Si:H. 2 O 5 The second L layer 140 may be deposited on SiO 2 The second O layer 135 is formed on the substrate. Therefore, the final filter coating portion 110 can be shown in the manner in which it is deposited: substrate-Si:H-SiO 2 -Ta 2 O 5 -Si:H-SiO 2 -Ta 2 O 5However, in some embodiments, the O layer 135 can act as a transition layer (e.g., substrate - Si:H - SiO x -Ta 2 O 5 -Si:H - SiOx - Ta 2 O 5 , where 0 < x < 2, such as SiO 1.3 , SiO 1.7 , etc.). In some embodiments, the O layer 135 can be of different materials (e.g., the first O layer 135 can be SiO 2 and the second O layer 135 can be SiO 1.3 ). Additionally or alternatively, one or more of the H layers 130 can include oxygen or oxygen - containing materials (e.g., SiOH, SiGeOH, SiGeO, etc.). Additionally or optionally, the final filter coating portion 110 can include a first Si:H layer deposited on the substrate, a first SiO 2 layer deposited on the first Si:H layer, a first Ta 2 layer deposited on the first SiO 2 O 5 layer, a second Si:H layer deposited on the first Ta 2 O 5 layer, a second SiO 2 layer deposited on the second Si:H layer, a second Ta 2 layer deposited on the second SiO 2 O 5 layer, and a third SiO 2 O 5 layer deposited on the second Ta 2 layer.

[0101] In some embodiments, the filter coating portion 110 can be manufactured using a sputtering process. For example, the filter coating portion 110 can be manufactured using a pulsed magnetron-based sputtering process to sputter layers 130, 135, 140, and / or 145 on a substrate 120, which can be a glass substrate or another type of substrate. In some embodiments, multiple cathodes can be used in the sputtering process, such as a first cathode sputtering silicon and a second cathode sputtering germanium. In this case, the multiple cathodes can be associated with a tilt angle of the first cathode relative to the second cathode, the tilt angle being selected to ensure a specific concentration of germanium relative to silicon, as described above. In some embodiments, a hydrogen flow can be added during the sputtering process to hydrogenate the silicon or silicon-germanium. Similarly, a nitrogen flow can be added to the sputtering process to nitride the silicon or silicon-germanium. In some embodiments, the filter coating portion 110 can be annealed using one or more annealing processes, such as a first annealing process at a temperature between about 280 degrees Celsius or about 200 degrees Celsius to about 400 degrees Celsius, a second annealing process at about 320 degrees Celsius or about 250 degrees Celsius to about 350 degrees Celsius, etc. In some embodiments, the filter coating portion 110 can be manufactured using SiGe:H coated from a target, such as with respect to Figures 1A-1C For example, a SiGe compound target having a selected silicon-germanium ratio may be sputtered to produce the filter coating portion 110 having a specific silicon-germanium ratio.

[0102] In some embodiments, the filter coating portion 110 can be associated with causing a reduced angular shift relative to the angular shift caused by another type of filter. For example, based on the refractive index of the H layer 130 relative to the refractive index of the L layer 140, the filter coating portion 110 can cause a reduced angular shift relative to another type of filter having another type of high refractive index material.

[0103] In some embodiments, the filter coating portion 110 is attached to a substrate, such as substrate 120. For example, the filter coating portion 110 can be attached to a glass substrate or another type of substrate. Additionally or alternatively, the filter coating portion 110 can be applied directly to the detector or to a set of silicon wafers that include a detector array (e.g., using photolithography, a lift-off process, etc.). In some embodiments, the filter coating portion 110 can be associated with an incident medium. For example, the filter coating portion 110 can be associated with an air medium or a glass medium as the incident medium. In some embodiments, the filter 100, 100', 100" can be disposed between a set of prisms. In another example, another incident medium, such as a transparent epoxy resin, can be used, and / or another substrate, such as a polymer substrate (e.g., a polycarbonate substrate, a cyclic olefin copolymer (COP) substrate, etc.) can be used.

[0104] In some embodiments, the filter 100, 100', 100" can be an interference filter having a transmission passband with a transmittance level greater than 90%. For the transmission passband associated with the transmittance level, the transmission passband is defined as a low wavelength boundary with a transmittance greater than 90% at the lowest wavelength and a high wavelength boundary with a transmittance less than 90% at the highest wavelength. In some examples, the transmission passband can have an average transmittance greater than 90%, greater than 94%, or greater than 95%. For example, the average transmittance in the passband can be greater than 94%, and the peak transmittance in the passband can be greater than 97%, which can depend on the wavelength range (for example, the above values ​​can apply to wavelengths greater than about 840nm, the above values ​​can be lower by about 2% at shorter wavelengths, and SiGe:H can also have a lower transmittance).

[0105] In some embodiments, the optical filter 100, 100', 100" can provide blocking outside the passband (e.g., a stopband on one or both sides of the passband) in the wavelength range of 400nm to 1100nm or in the wavelength range of 300nm to 1100nm. In some embodiments, the optical filter 100, 100', 100" can have a blocking level within the stopband greater than optical density 2 (OD2) in the wavelength range of 400nm to 1100nm, a blocking level within the stopband greater than optical density 3 (OD3) in the wavelength range of 300nm to 1100nm, or a blocking level greater than optical density 4 (OD4) in the wavelength range of 300nm to 1100nm. In some examples, the optical filter 100, 100', 100" can provide a blocking level greater than OD2 in the range of 400nm to 800nm ​​or a blocking level greater than OD3 in the range of 400nm to 800nm. For the stopband associated with the blocking level, the stopband at the wavelength below the passband is defined by the high wavelength boundary of the highest wavelength with a blocking level greater than the specified OD level (e.g., OD2 or OD3), and the stopband at the wavelength above the passband is defined by the lowest wavelength with a blocking level greater than the specified OD level (e.g., OD2 or OD3). In some examples, the stopband has an average blocking level greater than OD2 or OD3. In some examples, the optical filter 100, 100', 100" can provide an average blocking level of OD2 in the range of 400nm to 800nm, or greater than OD4, or an average blocking level of OD3 in the range of 400nm to 800nm.

[0106] In some cases, the filter 100, 100', 100" can be a long wavelength pass edge filter, and the passband has an edge wavelength in the wavelength range of 800nm ​​to 1100nm. However, in most cases, the filter 100, 100', 100" is a bandpass filter, such as a narrow bandpass filter. Typically, the center wavelength of the passband is in the wavelength range of 800nm ​​to 1100nm. The full width at half maximum (FWHM) of the passband is less than 60nm. In some examples, the passband can have a FWHM less than 55nm, less than 50nm, or less than 45nm. The entire passband can be in the wavelength range of 800nm ​​to 1100nm. In some examples, the FWHM may depend on various factors, including the application, light source thermal management, design of the filter 100, 100', 100", angular range, etc. For example, at 5nm, the thermal control device can operate within a narrow angular range, and the light source and filter 100, 100', 100" have manufacturing tolerances that meet a threshold (e.g., less than 1nm). In another example, at 120nm, the device can have a light source with a high temperature variation of the light source wavelength, and can operate over a large temperature range (e.g., from negative 40° to 120° Celsius) for a large acceptance angle. In this case, the light source can have a more flexible manufacturing tolerance (e.g., + / -10nm). In some embodiments described herein, the passband can be defined as including wavelengths with transmission levels greater than 90%, greater than 94%, greater than 95%, etc. However, it should be understood that in other examples, there may be another suitable definition of the passband. Additionally, in some embodiments described herein, the stopband can be defined as including wavelengths with transmission levels greater than OD2, greater than OD3, greater than OD4, etc. However, it should be appreciated that in other examples there may be another suitable definition of the stopband.

[0107] In some embodiments, the filter 100, 100', 100" can have a low center wavelength shift as the incident angle changes. As the incident angle changes from 0° to 30°, the CWL of the passband shifts in amplitude by less than 20nm. In some examples, as the incident angle changes from 0° to 30°, the CWL of the passband can shift in amplitude by less than 15nm. As the incident angle changes from 0° to 30°, the CWL of the passband shifts in amplitude between 20nm and 6nm. As the incident angle changes from 0° to 30°, the CWL of the passband shifts in amplitude by less than 12nm. As the incident angle changes from 0° to 30°, the CWL of the passband shifts in amplitude between 12nm and 6nm.

[0108] As mentioned above, Figures 1A-1C Only one or more examples are provided. Other examples may be related to Figures 1A-1C Different than described.

[0109] Figures 2A-2D is a diagram of one or more examples of the optical and / or mechanical properties of a set of materials related to one or more exemplary embodiments described herein.

[0110] As Figure 2A shown, and by graph 200, a filter having the configuration shown and / or described above with reference to Figures 1A-1C wherein the H layer 130 includes Si:H as the high refractive index material and the L layer 140 includes Ta 2 O 5 as the low refractive index material (e.g., having a second order spacer layer) can achieve a lower angular shift compared to a design wherein the H layer 130 includes Si:H as the high refractive index material and the L layer 140 includes SiO 2 as the low refractive index material. For example, Figure 2A shows a diagram depicting the percentage of transmission as a function of wavelength for six different designs. In particular, Figure 2A each of the diagrams shown in 2 includes three designs wherein the L layer 140 includes SiO x as the low refractive index material, having a first order spacer layer, a second order spacer layer, and a third order spacer layer including Si:H; and three designs including wherein the O layer 135 and the P layer 145 include oxides such as silicon oxide (any concentration) (e.g., SiO 2 where 0 < x < 2), silicon dioxide (SiO 2 ) ; also includes three designs wherein the L layer 140 includes Ta 2 O 5 as the low refractive index material, having a first order spacer layer, a second order spacer layer, and a third order spacer layer including Si:H. As shown, all designs have substantially similar performance at an AOI of 0 degrees.

[0111] As Figure 2B shown, and by graph 210, the thickness (in nm) of a filter having the configuration shown and / or described above with reference to Figures 1A-1C can depend on the material of the low refractive index material used in the L layer 140. For example, as described above with reference to Figure 2A SiO 2 and Ta 2 O 5 have bandpasses that provide substantially similar performance at an AOI of 0 degrees. However, as shown in graph 210, using Ta 2 O 5 as the low refractive index material in the L layer 140 (or other reflective layer) and / or including oxides such as silicon oxide (any concentration) (e.g., SiO x where 0 < x < 2) or silicon dioxide (SiO2 ) transition layer, compared with the use of SiO 2 As a low refractive index material, regardless of the order of the spacer layers, the design increases the overall design thickness. 2 O 5 The physical thickness of the design is greater than 3500nm, including SiO 2 The design has a physical thickness of less than 3250nm for the first order spacer layer, including Ta 2 O 5 The physical thickness of the design is greater than 4000nm, including SiO 2 The physical thickness of the second order spacer layer is about 3600nm, including Ta 2 O 5 The physical thickness of the design is close to 4500nm, including SiO 2 The physical thickness of the third order spacer layer is about 4000nm. 2 O 5 The design may increase the overall design thickness because Si:H and Ta 2 O 5 The index ratio between Si:H and SiO is lower than 2 The exponential ratio.

[0112] like Figure 2C As shown, and by graph 220, for low refractive index materials using Ta 2 O 5 The undesirable downward shift of the center wavelength (CWL) can be reduced to increase AOI. For example, graph 220 shows the inclusion of Ta at different bandpass spacing layer sequences. 2 O 5 The design and inclusion of SiO 2 As shown in the figure, compared with the design containing SiO 2 Compared with the design including Ta 2 O 5 The CWL shift down in any bandpass spacing layer sequence is usually small because Ta 2 O 5 The refractive index is higher than that of SiO 2 Therefore, with the above reference Figures 1A-1C In the filter configuration shown and / or described, a material having a relatively high refractive index (e.g., Ta 2 O 5 Instead of SiO 2 ) can usually reduce the bandpass angle deviation.

[0113] like Figure 2DAs shown, and by graph 230, for low refractive index materials using Ta 2 O 5 Undesirable stresses imposed by a coating (e.g., coating 180) on a substrate (e.g., substrate 120) can be reduced. For example, graph 230 shows the reduction in the amount of Ta based on the coating used. 2 O 5 Or SiO 2 Comparison of the total stress (in megapascals (MPa)) exerted by the bandpass coatings of the SiO 2 For any bandpass spacing layer sequence, including Ta 2 O 5 The total applied stress of the design is usually smaller because the magnetron sputtered Ta 2 O 5 The applied stress is significantly lower than that of magnetron sputtered SiO 2 Therefore, with the above reference Figures 1A-1C In the optical filters of the configuration shown and / or described, the use of materials having relatively low stress can reduce the stress applied to the substrate.

[0114] In this way, the material with a higher refractive index (Ta 2 O 5 ) instead of materials with a lower refractive index (e.g. SiO 2 ) can generally reduce the bandpass angle shift, which can allow (thinner) lower order spacer layers to be used. For example, Figure 2B As shown, including Ta 2 O 5 The first order spacer layer may have a 2 The second order spacer layer is of similar thickness and contains Ta 2 O 5 The second sequential spacer layer may have a 2 The third order spacer layer has a similar thickness. In addition, Figure 2C As shown, including Ta 2 O 5 The first order spacer layer may have a 2 The second order spacer layer is similarly offset at an angle and contains Ta 2 O 5 The second sequential spacer layer may have a 2 The third order spacer layer is similarly offset at an angle. Figure 2D As further shown, from the SiO 2 The second sequential spacer layer moves to contain Ta 2 O 5The first order spacer layer resulted in lower stress (while providing similar angular offset and similar thickness), and the 2 The third sequential spacer layer moves to contain Ta 2 O 5 The second order spacer layer also results in lower stress. In this way, by using a material with a higher refractive index, the stress imposed on the substrate by the spacer layer thickness can be reduced while still achieving a similar angular shift. For example, although the previous description mentions using a material such as Ta 2 O 5 The higher refractive index material replaces the material with a lower refractive index (e.g., SiO 2 ) but can be used with a 2 Other materials with higher refractive index (such as Nb 2 O 5 、TiO 2 etc.) to achieve similar benefits.

[0115] In some embodiments, in a system having Si:H and Ta 2 O 5 In the bandpass design, Si:H and Ta 2 O 5 The absorption at the interface leads to a lower transmission percentage. 2 O 5 Add tightly bound oxygen (e.g., SiO 2 、Al 2 O 3 Very thin layers of materials such as Si:H and Ta can prevent interface absorption that reduces the transmission percentage. In addition or alternatively, 2 O 5 Add a very thin layer of non-oxygen-reactive materials (e.g., aluminum nitrite, Si 3 N 4 In this way, the interfacial absorption can be reduced and the transmission percentage can be increased without adding Si:H and Ta. 2 O 5 The thin layers between the low transmission band and the high transmission T band can be tightly controlled because the thin layers are a small percentage of the overall design thickness. In addition, for filters that can benefit from a sharper transition between the low transmission band and the high transmission T band but cannot accommodate thicker coatings due to stress limitations, using the low stress approach can allow the use of more Fabry-Perot cavities, which can sharpen the transition between the low transmission band and the high transmission T band without exceeding the stress limit.

[0116] In this way, specific materials for the L layer 140 can be selected to reduce stress in the bandpass coating, which makes the wafer less prone to warping and therefore easier to handle before singulation. Otherwise, if less warping is desired, an additional stress-balancing coating is required on the back side of the wafer, which increases cost and increases the likelihood of the wafer cracking during handling. In addition, if the stress in the bandpass coating is less, thinner substrates can be used to manufacture the filter, which allows the sensor system to be thinner using thinner filters, and thinner filters have more flexibility during assembly and are less likely to have parts contact, which can cause damage, performance degradation, etc. In addition, without exceeding stress tolerance, more cavities can be used to sharpen the transition, which can result in better signal-to-noise ratio, and lower angular offset in the bandpass coating can achieve narrower bandwidth and better signal-to-noise ratio at the same optical angle.

[0117] As mentioned above, Figures 2A-2D Only one or more examples are provided. Other examples may be related to Figures 2A-2D Different than described.

[0118] Figures 3A-3D is a diagram of one or more examples 300 of a sputter deposition system for making one or more exemplary embodiments described herein.

[0119] like Figure 3A As shown, the example sputtering deposition system may include a vacuum chamber 310, a substrate 320, a cathode 330, a target 331, a cathode power supply 340, an anode 350, a plasma activation source (PAS) 360, and a PAS power supply 370. The target 331 may include a silicon material, a silicon-germanium material of a specific concentration selected based on the optical properties of a specific concentration, and the like. In another example, the angle of the cathode 330 may be configured so that a specific concentration of silicon and / or silicon-germanium is sputtered onto the substrate 320, as described herein. The PAS power supply 370 may be used to power the PAS 360 and may include a radio frequency (RF) power supply. The cathode power supply 340 may be used to power the cathode 330 and may include a pulsed direct current (DC) power supply. In this case, the sputtering deposition system may sputter one or more layers onto the substrate 320 by DC sputtering.

[0120] like Figure 3A As shown, the target 331 can be in a hydrogen atmosphere (H 2) and inert gas (e.g., argon) to deposit hydrogenated silicon (Si:H) material, hydrogenated silicon-germanium (SiGe:H) material, etc. as a layer on substrate 320. The inert gas can be provided to the chamber through anode 350 and / or PAS360. Hydrogen is introduced into vacuum chamber 310 through PAS360 for activating hydrogen. Additionally or alternatively, cathode 330 can cause hydrogen activation, in which case hydrogen can be introduced from another part of vacuum chamber 310, or anode 350 can cause hydrogen activation, in which case anode 350 can introduce hydrogen into vacuum chamber 310. In some embodiments, hydrogen can be in the form of hydrogen, a mixture of hydrogen and a rare gas (e.g., argon), etc. PAS360 can be located near the threshold of cathode 330, allowing plasma from PAS360 and plasma from cathode 330 to overlap. The use of PAS360 can allow Si:H and / or SiGe:H layers to be deposited at a relatively high deposition rate. In some embodiments, the Si:H and / or SiGe:H layer is deposited at a deposition rate of about 0.05 nm / s to about 2.0 nm / s, about 0.5 nm / s to about 1.2 nm / s, about 0.8 nm / s, and the like.

[0121] Although the sputtering process is described herein with respect to a specific geometry and a specific embodiment, other geometries and other embodiments are possible. For example, hydrogen gas can be injected from another direction, from a gas manifold near the threshold of cathode 330, etc.

[0122] like Figure 3B-3C As shown, a similar sputtering deposition system includes a vacuum chamber 310, a substrate 320, a first cathode 380, a second cathode 390, a first target 381, a second target 391, a cathode power supply 340, an anode 350, a PAS 360, and a PAS power supply 370. In this case, the first target 381 may be a silicon target and the second target 391 may be a germanium target. Therefore, as described herein, the first target 381 may be referred to as a silicon target 381, and the second target 391 may be referred to as a germanium target 391. However, it should be understood that the first target 381 and / or the second target 391 may be made of other suitable materials to form a high refractive index material layer.

[0123] like Figure 3B As shown, silicon target 381 is oriented at approximately 0 degrees relative to substrate 320 (e.g., approximately parallel to substrate 320), and germanium target 391 is oriented at approximately 120 degrees relative to substrate 320. In this case, silicon and germanium are sputtered from silicon target 381 and germanium target 391 onto substrate 320 by cathode 380 and cathode 390, respectively.

[0124] like Figure 3CAs shown, in a similar sputtering deposition system, silicon target 381 and germanium target 391 are each oriented at approximately 60 degrees relative to substrate 320, and silicon and germanium are sputtered from silicon target 381 and germanium target 391 onto substrate 320 by cathode 380 and cathode 390, respectively.

[0125] like Figure 3D As shown, in a similar sputtering deposition system, the silicon target 381 is oriented at about 120 degrees relative to the substrate 320, and the germanium target 391 is oriented at about 0 degrees relative to the substrate 320. In this case, silicon and germanium are sputtered from the silicon target 381 and the germanium target 391 onto the substrate 320 by the cathode 380 and the cathode 390, respectively.

[0126] about Figures 3A-3D Each configuration of components in the silicon sputter deposition system can result in different relative concentrations of silicon, silicon and germanium, etc. Although described herein with respect to different configurations of components, different relative concentrations of silicon and germanium can also be achieved using different materials, different manufacturing processes, etc.

[0127] As mentioned above, Figures 3A-3D Only one or more examples are provided. Other examples may be related to Figures 3A-3D Different than described.

[0128] Figures 4A-4B is a graph of one or more examples of optical properties of a set of materials related to one or more example embodiments described herein.

[0129] like Figure 4A As shown, and by graph 410, a set of characteristics are determined, for example, for a SiGe layer (e.g., a SiGe:H layer used in an optical filter). In general, an increase in the cathode angle of the cathode sputtered silicon may correspond to an increase in the germanium content relative to the silicon content in the optical filter, as described with respect to Figure 3B-3D For example, for a high refractive index layer of a filter deposited at 30 degrees, the high refractive index layer can be associated with a germanium content of about 7.5%. Similarly, for a deposition at 35 degrees, the filter can be associated with a germanium content of about 22%, and for a deposition at 50 degrees, the filter can be associated with a germanium content of about 90%.

[0130] like Figure 4AAs further shown in FIG. 4 and by graph 410, a refractive index n at a wavelength of 950 nm is provided for a set of layers of a high refractive index material based on a cathode angle (in degrees) at which sputtering is performed to sputter material to form the set of layers. As shown, for silicon germanium (SiGe) and annealed silicon germanium (SiGe-280C) (e.g., silicon germanium that has been subjected to an annealing process at 280 degrees Celsius (C)), an increase in cathode angle corresponds to an increase in refractive index. In addition, the refractive index of the silicon layer including germanium is greater than the refractive index of the silicon layer without germanium, such as a silicon (Si)-based filter and an annealed silicon (Si-280C)-based filter, thereby improving the performance of the filter including the SiGe layer.

[0131] like Figure 4B As shown, and by graph 420, another set of optical properties is determined for a set of high refractive index material layers. As shown, the absorption at a wavelength of 950nm can be determined based on the material type used for the high refractive index material layer and the cathode angle in the sputtering process used to deposit the high refractive index layer. For example, increased germanium content (e.g., increased cathode angle) is generally associated with increased absorption (or loss). However, relative to unannealed SiGe, annealed SiGe (SiGe-280C) is associated with reduced absorption of filters that are associated with similar cathode angles. For example, annealed SiGe can be associated with loss values ​​that meet the absorption threshold for the filter at a cathode angle corresponding to a refractive index that meets the refractive index threshold for low angle offset of the filter. In this way, annealing SiGe (or SiGe:H) can allow SiGe (or SiGe:H) to be used as a low angle offset coating with a relatively high refractive index that does not excessively absorb NIR light.

[0132] As mentioned above, Figure 4A and 4B Only one or more examples are provided. Other examples may be related to Figure 4A and 4B Different than described.

[0133] Figure 5A-5B is a graph of one or more examples of properties of a set of materials related to one or more embodiments described herein.

[0134] like Figure 5AAs shown, and through chart 510, a set of mechanical properties are determined for a set of high refractive index material layers. As shown, stress values ​​(in megapascals (MPa)) associated with the type of material used for the high refractive index material layer and the cathode angle of the sputtering process used to deposit the high refractive index material layer can be determined. Due to the sputtering process, the stress value can be a compressive stress on the high refractive index material layer. For example, an increased germanium content (e.g., an increased cathode angle) is associated with a reduced SiGe layer stress. As shown, at a similar cathode angle, annealed SiGe is associated with a reduced stress value relative to unannealed SiGe. For example, annealed SiGe can be associated with a stress value that meets the stress threshold for the filter at a cathode angle corresponding to a refractive index that meets the refractive index threshold for the filter. When the manufacturing process includes cutting the wafer into multiple parts for multiple filters, the reduced stress value can reduce the difficulty of manufacturing. In addition, relative to another type of material with a larger stress value, the reduced stress value can allow a substrate with a reduced thickness. In this way, annealing SiGe (or SiGe:H) can enable SiGe (or SiGe:H) to be used as a low angle offset coating with a higher refractive index and without excessive stress values, thereby improving the manufacturability of the filter and reducing the thickness of the filter relative to unannealed filters, especially compared to filters using pure silicon.

[0135] like Figure 5B As shown, and by graph 520, a set of optical characteristics is determined for a set of bandpass filters centered at a wavelength of 950 nm. As shown, the transmittance percentages of the first filter and the second filter are determined based on the utilization of annealing and the wavelength of light. For example, in Figure 5B , reference numeral 522 may correspond to a first filter and reference numeral 524 may correspond to a second filter, each of which may be associated with substantially similar parameters (e.g., a set of 4 cavities, a thickness of 3.1 microns, a set of high refractive index layers including SiGe, a set of high refractive index layers including silicon dioxide (SiO 2 ), no antireflection coating on the second side, and a cathode angle of 47.5 degrees (e.g., for a set of high refractive index layers, this may correspond to approximately 80% germanium). However, in Figure 5B , reference numeral 522 may correspond to a first filter in which annealing is used to form one or more high refractive index layers, and reference numeral 524 may correspond to a second filter in which annealing is not used.

[0136] Therefore, if Figure 5BAs shown, and by reference numerals 522 and 524, the use of annealing improves the transmittance at about 950 nm by about 7% (e.g., greater than 80% or about 85% at about 950 nm) relative to not using annealing for the filter. For example, as shown by reference numeral 524, when annealing is not used, the transmittance at about 950 nm can be less than 80%. In this way, annealing SiGe (or SiGe:H) can allow the SiGe (or SiGe:H) to be used as a low angle shift coating with improved transmittance relative to an unannealed filter. In another example, including an anti-reflective coating (e.g., on the back side of the filter) can improve the transmittance by an additional about 5% relative to a first filter without an anti-reflective coating.

[0137] Although Figure 5B While examples are shown with respect to a particular set of characteristics of the first and second filters, other examples described herein may demonstrate similar improved performance by annealing for other characteristics of the filters.

[0138] Although Figure 5B Examples are shown relating to optical properties of bandpass filters, and similarly improved optical properties may be associated with shortwave pass filters, longwave pass filters, antireflective coatings, non-polarizing beam splitters, polarizing beam splitters, dielectric reflectors, multi-bandpass filters, notch filters, multi-notch filters, neutral density filters, and the like.

[0139] As mentioned above, Figure 5A and 5B Only one or more examples are provided. Other examples may be related to Figure 5A and 5B Different than described.

[0140] Figures 6A-6C is a graph of one or more examples 600 of properties of a set of materials associated with one or more example embodiments described herein.

[0141] like Fig. 6A As shown, and by graph 610, a set of optical characteristics of a set of filters is shown, the set of filters including hydrogenated silicon (Si:H) based filters and hydrogenated silicon-germanium (SiGe:H) based filters. In this case, the set of filters can utilize silicon dioxide (SiO 2) as a low refractive index material. As shown in the figure, the transmittance percentage of the set of filters at a set of wavelengths is determined. In this case, the SiGe:H filter is associated with a refractive index of 3.871 at 950nm, while the Si:H filter is associated with a refractive index of 3.740 at 950nm. Since the SiGe:H filter has a higher refractive index than the Si:H filter, the SiGe:H filter can be associated with a reduced physical thickness. For example, the Si:H filter can be associated with a thickness of 6.3 microns, while the SiGe:H filter can be associated with a thickness of 5.4 microns. In addition, the SiGe:H filter can be associated with a higher blocking efficiency (for example, the SiGe:H filter can absorb more than the Si:H filter at about 700nm, resulting in a reduced quarter-wave stack coating blocking a wavelength range including 700nm).

[0142] like Figure 6B As shown, graph 620 shows a portion of graph 610 over a wavelength range of 950 nm to 1000 nm. As shown in graph 620, the angular shift of the Si:H filter at an angle of incidence (AOI) of 0 to 30 degrees is shown to be 16.5 nm, while the angular shift of the SiGe:H filter at an angle of incidence of 0 to 30 degrees is 13.0 nm. In this case, the SiGe:H filter is shown to have a reduced angular shift relative to the Si:H filter, thereby improving optical performance.

[0143] like Figure 6C As shown, and by graph 630, a Si:H filter and a SiGe:H filter (eg Figures 1A-1C The design and a set of optical properties of a filter) are described. As shown, the set of filters is associated with substrate sizes of 200 mm to 300 mm and substrate thicknesses of 0.15 mm to 0.7 mm. For each wafer size and wafer thickness, the SiGe:H filter is associated with a reduction in substrate deflection relative to the Si:H filter. In this way, the durability and manufacturability of the filter are improved. In addition, based on reducing the stress value, the substrate size can be increased relative to similar substrate thicknesses of other substrate designs based on reducing the possibility of fracture relative to other substrate designs with higher stress values.

[0144] As mentioned above, Figures 6A-6C Only provided as one or more examples. Other examples may vary from the Figures 6A-6C As described.

[0145] Figure 7A-7B is a diagram of one or more exemplary implementations 700 described herein. Fig. 7AAs shown, exemplary embodiment 700 may include sensor system 710. Sensor system 710 may be part of an optical system and may provide an electrical output corresponding to a sensor measurement. Sensor system 710 includes a filter structure 720, which includes a filter 730 and an optical sensor 740. For example, filter structure 720 may include filter 730 that performs a bandpass filtering function or another type of filter. Sensor system 710 includes an optical emitter 750 that emits an optical signal to a target 760 (e.g., a person, an object, etc.).

[0146] Although embodiments may be described herein in terms of an optical filter in a sensor system, embodiments described herein may be used in another type of system, may be used outside of a sensor system, etc. In some embodiments, the optical filter 730 may perform a polarization beam splitting function on the light. For example, the optical filter 730 may reflect a first portion of the light having a first polarization and may pass a second portion of the light having a second polarization when the second polarization is desired to be received by the optical sensor 740, as described herein. Additionally or alternatively, the optical filter 730 may perform a reverse polarization beam splitting function (e.g., beam combining) on ​​the light.

[0147] like Fig. 7AAs further shown, and by reference numeral 770, the input light signal is directed to the filter structure 720. The input light signal may include NIR light emitted by the optical emitter 750 and ambient light from the environment in which the sensor system 710 is used. For example, when the filter 730 is a bandpass filter, the optical emitter 750 may direct near infrared (NIR) light to the user for a gesture recognition system (e.g., a gesture performed by the target 760), and the NIR light may be reflected from the target 760 (e.g., the user) toward the optical sensor 740 to allow the optical sensor 740 to perform a measurement of the NIR light. In this case, the ambient light may be directed to the optical sensor 740 from one or more ambient light sources (e.g., a light bulb or the sun). In another example, multiple light beams may be directed to the target 760, and a subset of the multiple light beams may be reflected toward the filter structure 720, which may be disposed at an inclined angle relative to the optical sensor 740, as shown. In some embodiments, another inclined angle (e.g., a 0 degree inclined angle for a bandpass filter) may be used. In some embodiments, the filter structure 720 can be arranged and / or formed directly on the optical sensor 740, rather than being arranged at a distance from the optical sensor 740. For example, the filter structure 720 can be applied and patterned onto the optical sensor 740 using, for example, photolithography. In some examples, the filter structure 720 can include any of the elements of the above-mentioned filters 100, 100', 100", including the substrate 120, the coating 180, etc. In another example, the optical emitter 750 can direct the NIR light to another type of target 760, such as for detecting objects approaching a vehicle, detecting objects approaching a blind person, detecting approach to an object (e.g., using LIDAR technology), etc., and the NIR light and ambient light can thus be directed to the optical sensor 740.

[0148] like Fig. 7A As further shown, and by reference numeral 780, a portion of the optical signal passes through the filter 730 and the filter structure 720. For example, the filter 730 may include any of the filter coating portions 110 of the above-described filters 100, 100', 100", and may reflect the first polarization of light in a first direction. In this case, the filter 730 blocks visible light of the input optical signal without excessively blocking NIR light, and does not introduce excessive angular shift as the incident angle of the input optical signal increases.

[0149] like Fig. 7AAs further shown, and by reference numeral 790, based on the portion of the optical signal passed to the optical sensor 740, the optical sensor 740 can provide an output electrical signal to the sensor system 710, for example, for identifying a user's gesture or detecting the presence of an object. In some embodiments, another arrangement of the optical filter 730 and the optical sensor 740 can be utilized. For example, instead of passing the second portion of the optical signal in-line with the input optical signal, the optical filter 730 can direct the second portion of the optical signal in another direction to the optical sensor 740 at a different location. In another example, the optical sensor 740 can be an avalanche photodiode, an indium gallium arsenide (InGaAs) detector, an infrared detector, etc.

[0150] like Figure 7B As shown, a similar exemplary embodiment 700 may include a sensor system 710 , an optical filter structure 720 , an optical filter 730 , an optical sensor 740 , an optical emitter 750 , and a target 760 . Figure 7B A specific exemplary embodiment 700 is shown that includes an optical filter 730 as described herein.

[0151] The optical emitter 750 emits light at an emission wavelength in a wavelength range of 800 nm to 1100 nm. The optical emitter 750 emits modulated light (e.g., light pulses). The optical emitter 750 may be a light emitting diode (LED), an LED array, a laser diode, or a laser diode array. The optical emitter 750 emits light to a target 760, which reflects the emitted light back to the sensor system 710. When the sensor system 710 is a gesture recognition system, the target 760 is a user of the gesture recognition system. The sensor system 710 may also be a proximity sensor system, a three-dimensional (3D) imaging system, a distance sensing system, a depth sensor, and / or other suitable sensor systems.

[0152] The optical filter 730 is arranged to receive the emission light after being reflected by the target 760. The optical filter 730 has a passband including the emission wavelength and at least partially overlapping with the wavelength range of 800nm ​​to 1100nm. The optical filter 730 is a bandpass filter, such as a narrow bandpass filter. The optical filter 730 transmits the emission light from the optical emitter 750 while substantially blocking the ambient light.

[0153] The optical sensor 740 is configured to receive the emitted light after being transmitted by the optical filter 730. In some embodiments, the optical filter 730 is formed directly on the optical sensor 740. For example, the optical filter 730 can be coated and patterned (e.g., by photolithography) on a sensor (e.g., a proximity sensor) in wafer level processing (WLP).

[0154] When the sensor system 710 is a proximity sensor system, the optical sensor 740 is a proximity sensor that detects emitted light to sense the proximity of the target 760. When the sensor system 710 is a 3D imaging system or a gesture recognition system, the optical sensor 740 is a 3D image sensor (e.g., a charge coupled device (CCD) chip or a complementary metal oxide semiconductor (CMOS) chip) that detects emitted light to provide a 3D image of the target 760, which is, for example, a user. The 3D image sensor converts optical information into electrical signals, which are processed by a processing system (e.g., an application specific integrated circuit (ASIC) chip or a digital signal processor (DSP) chip). For example, when the sensor system 710 is a gesture recognition system, the processing system processes the 3D image of the user to recognize the user's gesture.

[0155] As mentioned above, Figure 7A-7B Only one or more examples are provided. Other examples may be related to Figure 7A-7B Different than described.

[0156] In this way, a set of hydrogenated silicon (Si:FI) layers, a set of SiGe-based layers, a set of hydrogenated SiGe (SiGe:H) layers, etc. can be used as a high refractive index material for a filter coating of a filter to provide out-of-band blocking of visible light, transmission of NIR light, and / or filtering of light with a reduced angular shift relative to another type of material used for a set of high refractive index layers. In addition, based on the use of Si:H, SiGe, SiGe:H, etc. and / or an annealing process, out-of-band blocking and in-band transmission are improved relative to another type of material.

[0157] Fig. 8A The refractive index at 800nm ​​to 1120nm wavelength is shown relative to the graph of the hydrogen flow rate of the deposited Si:H layer. As shown in the figure, the refractive index is usually reduced with the increase of the hydrogen flow rate. Generally, the refractive index changes approximately linearly with the hydrogen flow rate. In particular, in the wavelength range of 80nm to 1120nm, the refractive index of the Si:H layer produced with a hydrogen flow rate of 80 standard cubic centimeters per minute (sccm) is greater than 3.55. In some embodiments, the refractive index is greater than 3.65, greater than 3.7, greater than 3.75 and about 3.8 at 800nm.

[0158] Figure 8BShows a graph of the extinction coefficient at wavelengths from 800 nm to 880 nm versus the hydrogen gas flow rate of the as-deposited Si:H layer (the absorption coefficient is less than 0.0001 at wavelengths from 920 nm to 1120 nm). The extinction coefficient (such as the absorption coefficient) generally decreases with an increase in the hydrogen gas flow rate. Generally, the extinction coefficient varies approximately exponentially with the hydrogen gas flow rate. In particular, in the wavelength range from 800 nm to 1120 nm, the extinction coefficient of the silicon hydride layer produced at a hydrogen gas flow rate of 80 sccm is less than 0.0004.

[0159] As described above, Figures 8A-8B is provided only as one or more examples. Other examples may be different from those Figures 8A-8B described.

[0160] Fig. 9 is a diagram of Example 900 of the transmission spectrum of the filter described herein. For example, Fig. 9 shows the transmission spectra of various exemplary stacks of three materials compared to the transmission spectrum of a stack of an exemplary two materials of alternating SiO 2 and Si:H, which is shown by reference numeral 910. To fabricate a stack of three materials corresponding to reference numeral 920, these layers can be deposited as Figure 1A shown. For example, the O layer 135 can be deposited as a 3-nm SiO 2 layer, the H layer 130 can be deposited as a Si:H layer, the L layer 140 can be deposited as a Ta 2 O 5 layer, and a SiO 2 layer can be deposited before each Si:H layer. However, as described above, the depth analysis of the exemplary stack corresponding to reference numeral 120 can include filter options that include SiOH and / or SiO x , where 0 < x < 2. These layers may not appear as three distinct layers but rather as a transition from Si:H to Ta 2 O 5 .

[0161] To fabricate a stack of three materials corresponding to reference numeral 930, these layers can be deposited as Figure 1B shown. In this case, the O layer 135 and the P layer 145 can be deposited as 3-nm SiO 2 layers, the H layer 130 can be deposited as a Si:H layer, the L layer can be deposited as a Ta 2 O 5 layer, whereby a SiO 2 layer can be deposited before and after each Si:H layer. However, as described above, the depth analysis of the exemplary stack corresponding to reference numeral 930 can include filter options that include SiOH and / or SiOx , where 0 < x < 2. Examples include substrate - Si:H - SiO 2 - Ta 2 O 5 - SiO 2 - Si:H - SiO 2 - Ta 2 O 5 - SiO 2 ; substrate - Si:H - SiO x - Ta 2 O 5 - SiO x - Si:H - SiO x - Ta 2 O 5 ; substrate - SiOH - SiO x - Ta 2 O 5 - SiO x - SiOH - SiO x - Ta 2 O 5 , or a combination thereof, where for each O layer 135 and / or P layer 145, x can be unequal and 0 < x < 2 (e.g., SiO 1.3 , SiO 1.7 , Si, etc.). These layers may not appear as four distinct layers, but rather as a transition from Si:H to Ta 2 O 5 .

[0162] To fabricate a stack of three materials corresponding to reference numeral 940, these layers can be deposited as shown Figure 1A . For example, the O layer 135 can be deposited as a 6 nm SiO 2 layer, the H layer 130 can be deposited as a Si:H layer, the L layer 140 can be deposited as a Ta 2 O 5 layer, and a SiO 2 layer can be deposited before each Si:H layer. However, as described above, a depth analysis of an exemplary stack corresponding to reference numeral 940 can include filter options that include SiOH and / or SiO x , where 0 < x < 2. These layers may not appear as three distinct layers, but rather as a transition from Si:H to Ta 2 O 5 .

[0163] To fabricate a stack of three materials corresponding to reference numeral 950, these layers can be deposited as shown Figure 1B . In this case, the O layer 135 and the P layer 145 can be deposited as 6 nm SiO2 For the layer, the H layer 130 can be deposited as a Si:H layer, and the L layer 140 can be deposited as a Ta 2 O 5 layer, whereby the SiO 2 layer can be deposited before and after each Si:H layer. However, as described above, the depth analysis of the exemplary stack corresponding to reference numeral 950 can include a filter option that includes SiOH and / or SiO x , where 0 < x < 2. Examples include substrate - Si:H - SiO 2 -Ta 2 O 5 -SiO 2 -Si:H - SiO 2 -Ta 2 O 5 -SiO 2 ; substrate - Si:H - SiO x -Ta 2 O 5 -SiO x -Si:H - SiO x -Ta 2 O 5 ; substrate - SiOH - SiO x -Ta 2 O 5 -SiO x -SiOH - SiO x -Ta 2 O 5 , or combinations thereof, where for each O layer 135 and / or P layer 145, x can be unequal and 0 < x < 2 (e.g., SiO 1.3 , SiO 1.7 , Si, etc.). These layers may not appear as four distinct layers but rather as a transition from Si:H to Ta 2 O 5 .

[0164] To fabricate a stack of three materials corresponding to reference numeral 960, the Si:H and Ta 2 O 5 layers can be deposited alternately (e.g., without any SiO 2 layers). However, as described above, the depth analysis of the exemplary stack corresponding to reference numeral 960 can include a filter option that includes SiOH and / or Ta 2 O Y , where 0 < Y < 5. These layers may not appear as two distinct layers but rather as a transition from Si:H to Ta 2 O 5 .

[0165] To fabricate a stack of three materials corresponding to reference numeral 970, these layers can be deposited as shown Figure 1C . For example, the O layer 135 can be deposited as a 3 nm SiO 2 layer, the H layer 130 can be deposited as a Si:H layer, the L layer 140 can be deposited as a Ta 2 O 5 layer, and the SiO 2 layer can be deposited after each deposition of the Si:H layer. However, as described above, the depth analysis of the exemplary stack corresponding to reference numeral 970 can include a filter option that includes SiOH and / or SiO x , where 0 < x < 2. These layers may not appear as three distinct layers, but rather as a transition from Si:H to Ta 2 O 5 . Examples include substrate - Si:H - Ta 2 O 5 - SiO 2 - Si:H - Ta 2 O 5 - SiO 2 ; substrate - Si:H - Ta 2 O 5 - SiO x - Si:H - Ta 2 O Y ; substrate - SiOH - Ta 2 O 5 - SiO x - SiOH - Ta 2 O Y , or combinations thereof, where for each O layer 435, x may not be equal and 0 < x < 2 (e.g., SiO 1.3 , SiO 1.7 , Si, etc.), for each L layer 140 Y may not be equal, and 0 < Y < 5.

[0166] In the various examples provided above, in cases where the structure includes layers arranged as Si:H - SiO 2 - Ta 2 O 5 - SiO 2 - Si:H, etc., SiO x can be used as a transition material at the interface between the Si:H layer and the SiO 2 layer, e.g., from the Si:H layer to the SiO 2 layer, from the SiO 2 layer to the Si:H layer, etc. Additionally, in cases where the structure includes layers arranged as Si:H - SiO 2 - Ta 2 O5 In the case of layers such as SiO x Can be used as Si:H layer and SiO 2 The transition material at one or more interfaces between the layers, the top SiO x The portion may be less oxidized rather than fully oxidized, and only oxidized enough to prevent the silicon base layer from being oxidized by the Ta 2 O 5 In addition, as described above, the structure includes Si:H-Ta 2 O 5 - In the case of Si:H and other layers, there may be layers from Si:H to Ta 2 O 5 One or more transition materials, from Ta 2 O 5 One or more transition materials to Si:H, etc.

[0167] As mentioned above, Fig. 9 Only one or more examples are provided. Other examples may be related to Fig. 9 Different than described.

[0168] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the embodiments.

[0169] Some embodiments are described herein in conjunction with threshold values. As used herein, satisfying a threshold value may refer to a value greater than a threshold value, more than a threshold value, above a threshold value, greater than or equal to a threshold value, less than a threshold value, less than a threshold value, below a threshold value, less than or equal to a threshold value, equal to a threshold value, etc., depending on the context.

[0170] Although particular combinations of features are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below may be directly dependent on a claim, the disclosure of the various embodiments includes each dependent claim combined with every other claim in the claim set.

[0171] Unless explicitly stated, any element, behavior or instruction used herein should not be interpreted as critical or necessary. In addition, as used herein, the articles "one" and "an" are intended to include one or more items and can be used interchangeably with "one or more". In addition, as used herein, the article "the" is intended to include one or more items related to the article "the", and can be used interchangeably with "one or more". In addition, as used herein, the term "set" is intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.), and can be used interchangeably with "one or more". If only one item is intended to be used, the phrase "only one item" or similar language is used. In addition, as used herein, the term "having" and / or similar terms are intended to be open terms. In addition, unless explicitly stated otherwise, the phrase "based on" is intended to mean "based at least in part". In addition, as used herein, unless explicitly stated otherwise (e.g., if used in combination with "any" or "only one"), the term "or" is intended to be included and can be used interchangeably with "and / or" when used for a series.

Claims

1. A filter, include: A first layer includes a first material, The first material includes at least silicon and hydrogen; a second layer comprising a second material different from the first material, The second material comprises an oxide, and The second layer is adjacent to the first layer; a third layer including a third material different from the first material and the second material, The third material includes at least tantalum, and The third layer is adjacent to the second layer; as well as a fourth layer comprising the second material, The fourth layer is adjacent to the third layer. 2 . The optical filter according to claim 1 , wherein the first material is a hydrogenated silicon (Si:H) based material.

3. The filter according to claim 1, wherein the second material is based on silicon dioxide (SiO 2 ) materials.

4. The filter according to claim 1, wherein the third material is based on tantalum pentoxide (Ta 2 O 5 ) materials.

5. The optical filter according to claim 1, further comprising: include: A substrate is adjacent to the first layer.

6. The optical filter according to claim 1, further comprising: include: The fifth layer is adjacent to the fourth layer. The filter according to claim 6 , wherein the fifth layer comprises the first material.

8. The optical filter according to claim 6, further comprising: include: The sixth layer is adjacent to the fourth layer.

9. The filter of claim 8, wherein the sixth layer comprises the second material.

10. The optical filter according to claim 8, further comprising: include: A seventh layer is adjacent to the sixth layer and includes the third material.

11. A filter, include: A first layer includes a first material, The first material comprises an oxide; a second layer comprising a second material different from the first material, The second material includes at least one of the following: tantalum pentoxide (Ta 2 O 5 ) material, magnesium fluoride (MgF 2 ) material, zirconium oxide (ZrO 2 ) material, or yttrium oxide (Y 2 O 3 ) materials, and The second layer is adjacent to the first layer; and The third layer comprises the first material, The third layer is adjacent to the second layer.

12. The optical filter according to claim 11, wherein the second material is tantalum pentoxide (Ta 2 O 5 )Material.

13. The filter of claim 11, wherein the first material comprises at least silicon.

14. The optical filter according to claim 11, wherein the first material is silicon dioxide (SiO 2 )Material.

15. The optical filter according to claim 11, further comprising: include: The fourth layer is adjacent to the third layer.

16. The filter of claim 15, wherein the fourth layer comprises a third material different from the first material and the second material.

17. The optical filter according to claim 16, wherein the third material is a hydrogenated silicon (Si:H) material.

18. A filter, include: A first layer includes a first material, The first material includes at least silicon and hydrogen; a second layer comprising a second material different from the first material, The second material comprises an oxide, and The second layer is adjacent to the first layer; as well as A third layer includes a third material different from the first material and the second material, and the third layer is adjacent to the second layer.

19. The filter of claim 18, wherein the first material is a hydrogenated silicon (Si:H) based material, and The second material is based on silicon dioxide (SiO 2 ) materials.

20. The optical filter according to claim 18, further comprising: include: A substrate is adjacent to the first layer.

Images