Optical system, induced transmission filter and method of making optical filter

Abstract

An induced transmission filter may include an assembly of optical filter layers. This assembly of optical filter layers may include a first subset of optical filter layers comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen. The assembly of optical filter layers may also include a second subset of optical filter layers comprising a second material having a second refractive index. The second material may be different from the first material, and the second refractive index may be less than the first refractive index. The second material may comprise at least silver.

Description

Technical Field

[0001] This invention relates to induced transmission filters having silicon hydride and silver. [Cross-references to related applications]

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 016,731, filed April 28, 2020, entitled “INDUCED TRANSMISSION FILTER WITH HYDROGENATED SILICON AND SILVER”. The disclosure of the earlier application is considered part of this patent application, and is incorporated herein by reference. Prior Technology

[0003] An optical transmitter can emit light directed at one or more objects. For example, in a gesture recognition system, an optical transmitter can emit near-infrared (NIR) light toward a user and reflect the NIR light from the user toward an optical receiver. In this case, the optical receiver can capture information about the NIR light, and this information can be used to identify the gesture the user is performing. For example, the device can use this information to generate a three-dimensional representation of the user and identify the gesture based on that representation. In other examples, systems can use optical transmitters and receivers for ranging, object recognition, spectroscopy, health monitoring, etc.

[0004] In some cases, a specific pattern or band of emitted light may be required during light transmission. Therefore, light-shaping optics can be placed in the optical path between the optical transmitter and the target. Similarly, ambient light may interfere with the emitted light during transmission toward the target and / or reflection from the target to the optical receiver. In such cases, optical filters can be placed in the optical path between the target and the optical receiver. For example, the optical receiver can be optically coupled to an induced transmission filter, a bandpass filter, etc., to filter some wavelengths of light (e.g., corresponding to the wavelength of ambient light) and allow other wavelengths of light (e.g., corresponding to the wavelength of emitted NIR light) to pass through toward the optical receiver. Summary of the Invention

[0005] According to some possible implementations, an induced transmission filter may comprise a set of optical filter layers. This set of optical filter layers may include a first subset of optical filter layers comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen. The set of optical filter layers may also include a second subset of optical filter layers comprising a second material having a second refractive index. The second material may be different from the first material. The second material may comprise at least silver.

[0006] According to some possible implementations, a method may include depositing a first subset of optical filter layers of an optical filter, the first subset of the optical filter layers comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen; and depositing a second subset of the optical filter layers of the optical filter, the second subset of the optical filter layers comprising a second material having a second refractive index, and the second material being different from the first material, the second material comprising at least a metal. The metal may be silver.

[0007] According to some possible implementations, the optical system may include optical filters to filter input optical signals and provide filtered input optical signals. The optical filters may include a set of optical filter layers. The set of optical filter layers may include a first subset of optical filter layers comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen. The set of optical filter layers may include a second subset of optical filter layers comprising a second material having a second refractive index, the second material being different from the first material, the second material comprising at least silver. The optical system may include an optical receiver for receiving the filtered input optical signal and providing an output electrical signal. Simple Explanation of the Diagram

[0008] [Figure 1A]-[Figure 1F] are illustrations of exemplary transmission filters induced according to the various embodiments described herein.

[0009] Figures 2A-2D are illustrations of examples associated with induced transmission filters according to various embodiments described herein.

[0010] Figures 3A-3D are illustrations of examples associated with induced transmission filters according to various embodiments described herein.

[0011] [Figure 4] is a diagram illustrating an example of an assembly of optical filter layers associated with an induced transmission filter according to various embodiments described herein.

[0012] Figures 5A-5D are illustrations of examples associated with sputtering systems for depositing an array of optical filter layers according to various embodiments described herein.

[0013] Figures 6A-6B are illustrations of examples of optical systems including induced transmission filters according to various embodiments described herein.

[0014] [Figure 7] is a flowchart of an exemplary process related to the manufacture of an induced transmission filter according to the various embodiments described herein. Implementation

[0015] The following detailed description of exemplary embodiments is taken with reference to the accompanying drawings. The same element symbols in different drawings may identify the same or similar elements. The following description uses optical systems (e.g., gesture recognition systems, spectrometers, or health monitoring systems, and other examples) as examples. However, the techniques, principles, procedures, and methods described herein can be used with any sensor (including, but not limited to, other optical and spectral sensors).

[0016] An optical receiver can receive light from a light source such as an optical emitter. For example, an optical receiver can receive near-infrared (NIR) light reflected from an optical emitter and from a target. Additionally or alternatively, an optical receiver can receive light from another frequency band that is not reflected from the target (e.g., in ranging or communication applications, and other paradigms). Targets can include people (e.g., users and non-users), animals, inanimate objects (e.g., cars or other vehicles, trees, obstacles, furniture, walls), etc. An optical receiver can receive light from an optical emitter as well as ambient light (e.g., visible spectrum light). Ambient light can include light from one or more light sources separate from the optical emitter (e.g., sunlight, light from a light bulb, etc.).

[0017] Ambient light can reduce the accuracy of determinations related to emitted light. For example, in a gesture recognition system, ambient light may reduce the accuracy of generating a 3D image of a target using NIR light. In some other paradigms, information about NIR light can be used to identify a user, user characteristics (e.g., height or weight), user status (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. In such paradigms, the presence of ambient light or light with unexpected wavelengths may reduce the accuracy of decisions performed using information from an optical receiver. Therefore, the optical receiver can be optically coupled to an optical filter (e.g., a bandpass filter) to filter ambient light and allow NIR light to pass through toward the optical receiver. While some embodiments are described with respect to an optical filter coupled to an optical receiver, other embodiments can be applied to light-shaping and filtering optics coupled to an optical emitter.

[0018] Figures 1A-1F are illustrations of examples of induced transmission filters.

[0019] As shown in Figure 1A, an induced transmission filter (ITF) bandpass filter 100 may include a first set of filter layers having a first material (e.g., silver (Ag)) and a second set of filter layers having a second material (e.g., niobium titanium oxide (NbTiOx)). The first and second materials can be selected to achieve out-of-band blocking for a specific spectral range. In other words, the first and second materials (and the number and thickness of their layers) are selected so that light in the first frequency band can pass through and light in the second frequency band is blocked, thereby enabling the sensing of light in the first frequency band without negative performance caused by light of unintended wavelengths in the second frequency band. For some sensing applications, silver may be selected as the first material, and an oxide (such as NbTiOx shown) may be selected as the second refractive material. However, silver may react with oxides, which may negatively affect the optical properties of the filter comprising silver and oxides. Adding a third material (e.g., zinc oxide (ZnO) shown) as a buffer layer can reduce the reaction between silver and oxides. As shown in Figures 1B and 1C, the ITF bandpass filter 100 exhibits approximately 40%-45% transmittance at a center wavelength of 820 nanometers (nm) and an angular shift of approximately 46 nm at incident angles up to 60 degrees. Furthermore, as shown in Figure 1B, leakage (unintended transmittance) may occur at the first harmonic of the center wavelength of the ITF bandpass filter 100 (e.g., between approximately 400 nm and approximately 470 nm), which could lead to poor optical performance.

[0020] As shown in Figures 1D-1F, further adding a dielectric stack of a high-refractive-index material such as amorphous silicon (a-Si) (the fourth material) and a low-refractive-index material such as silicon dioxide (SiO2) (the fifth material) can further improve the optical performance of the ITF bandpass filter 150, which includes silver and oxides. For example, as shown in Figures 1E and 1F, the ITF bandpass filter 150 can have a transmittance of approximately 53%, which can eliminate light leakage (unintended transmittance) that occurs at approximately 450 nm for the ITF bandpass filter 100, and can slightly reduce the angular displacement at a 60-degree incident angle to 40 nm.

[0021] As indicated above, Figures 1A-1F are provided as examples. Other examples may differ from those described with respect to Figures 1A-1F.

[0022] However, adding a third, fourth, or fifth material can lead to difficulties in manufacturing optical filters. For example, some deposition systems limit the number of materials that can be deposited to no more than two or three. Therefore, manufacturing optical filters that include three, four, five, or even more materials may require multiple deposition operations, which can be expensive and potentially time-consuming. Furthermore, the aforementioned optical filters may have relatively large angular displacements.

[0023] Therefore, some embodiments described herein can utilize non-oxide materials to pair with, for example, silver in an ITF bandpass filter. For example, an ITF bandpass filter may include a first set of silver layers and a second set of layers (e.g., silicon hydride (Si:H), silicon-germanium hydride (SiGe-H), germanium hydride (Ge-H), and other examples). Replacing oxide layers with, for example, silicon hydride eliminates the need for a protective layer (e.g., ZnO) to prevent reactions between silver and oxides. Furthermore, because silicon hydride can be sputtered from a silicon target, which can also sputter silicon dioxide, an ITF bandpass filter comprising, for example, amorphous silicon, silver, and silicon dioxide layers can be sputtered using a single sputtering process. Moreover, compared to the aforementioned ITF bandpass filters 100 and 150, ITF bandpass filters made using silver, silicon hydride, and silicon dioxide can achieve reduced angular displacement and improved transmittance.

[0024] Figures 2A-2D are illustrations of examples associated with ITF bandpass filters.

[0025] As shown in Figure 2A, the ITF bandpass filter 200 may include alternating layers of silver and amorphous silicon, and a dielectric stack formed by alternating layers of silicon dioxide and amorphous silicon. In this case, as shown in Figures 2B-2D, compared to ITF bandpass filters 100 and 150, at a center wavelength of approximately 820 nm, the ITF bandpass filter 200 achieves improved transmittance (e.g., greater than 60% and between approximately 65% ​​and 70% at the center wavelength) and reduced angular displacement (e.g., reduced from 26 nm to 8.1 nm at a 40-degree incident angle). Furthermore, the ITF bandpass filter 200 suppresses light leakage at the aforementioned 450 nm, thereby improving optical performance compared to the ITF bandpass filter 100. In this way, using, for example, amorphous silicon instead of oxide layers to pair with silver results in improved optical performance with a reduced amount of material, thereby improving manufacturability, as described in more detail herein. Furthermore, the ITF bandpass filter 200 has a thickness of 626.8 nm, which is about half the thickness of, for example, the ITF bandpass filter 150 (1265.6 nm), thereby enabling improvements in the miniaturization of optical systems, reduction in costs, and so on.

[0026] As indicated above, Figures 2A-2D are provided as examples. Other examples may differ from those described with respect to Figures 2A-2D. As examples, the number and arrangement of the equipment shown in Figures 2A-2D are provided.

[0027] Figures 3A-3D are illustrations of examples associated with ITF bandpass filters.

[0028] As shown in Figure 3A, the ITF bandpass filter 300 can be configured to achieve a low angular shift at a center wavelength of 950 nm (and using collimated light). The ITF bandpass filter 300 may include a filter layer coating with a thickness of 1.96 μm on a first side of the substrate and a filter layer coating with a thickness of 1.1 μm on a second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 300 can be between approximately 22.3 nm and approximately 22.7 nm, and the angular shift can be approximately 3.2 nm (relative to a center wavelength of -3.2 nm) at an incident angle of 40 degrees. As shown in Figure 3B, the ITF bandpass filter 310 can be configured to achieve a low angular shift at a center wavelength of 940 nm (and using collimated light). The ITF bandpass filter 310 may include a filter layer coating with a thickness of 2.25 μm on a first side of the substrate and a filter layer coating with a thickness of 1.15 μm on a second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 310 can be between approximately 20.5 nm and approximately 23.3 nm, and the angular displacement can be approximately 10.0 nm (relative to the center wavelength of -10.0 nm) when the incident angle is 40 degrees.

[0029] As shown in Figure 3C, the ITF bandpass filter 320 can be configured to achieve a low angular shift at a center wavelength of 940 nm (and with collimated light), but with a narrower bandwidth compared to ITF bandpass filters 300 and 310. The ITF bandpass filter 320 may include a 2.25 μm thick filter layer coating on a first side of the substrate and a 1.15 μm thick filter layer coating on a second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 320 can be between approximately 16.3 nm and approximately 18.5 nm, and the angular shift can be approximately 7.95 nm (relative to a center wavelength of -7.95 nm) at an incident angle of 40 degrees. As shown in Figure 3D, the ITF bandpass filter 330 can be configured to achieve a low angular shift at a center wavelength of 1550 nm (and with collimated light). The ITF bandpass filter 330 may include a filter layer coating with a thickness of 4.4 μm on a first side of the substrate and a filter layer coating with a thickness of 2.3 μm on a second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 330 may be between approximately 40.0 nm and approximately 45.5 nm, and the angular displacement may be approximately 7.46 nm (relative to a center wavelength of -7.46 nm) when the incident angle is 40 degrees.

[0030] As indicated above, Figures 3A-3D are provided as examples. Other examples may differ from those described with respect to Figures 3A-3D. The number and arrangement of equipment shown in Figures 3A-3D are provided as examples.

[0031] Figure 4 is a schematic diagram of an exemplary optical filter 400. As further shown in Figure 4, the optical filter 400 may include an optical filter coating portion 410 and a substrate 420.

[0032] As shown in Figure 4, the optical filter coating portion 410 includes an assembly of optical filter layers. For example, the optical filter coating portion 410 includes a first assembly of layers 430, a second assembly of layers 440, and in some embodiments a third assembly of layers 450. The first assembly of layers 430 may include an assembly of high refractive index material layers, and may be referred to herein as H layer 430. For example, in some embodiments, H layer 430 may include a material comprising hydrogen and silicon (e.g., a silicon-silicon (Si:H) layer, a silicon-germanium (SiGe:H) layer, etc., comprising silicon (Si) and hydrogen (H). In some embodiments, H layer 430 may include a material comprising silicon and germanium (e.g., a silicon-germanium (SiGe) layer, etc.).

[0033] These high-refractive-index materials can have refractive indices greater than 3, 3.2, 3.5, 3.6, 4, etc., in the range of at least 800 nanometers (nm) to 1700 nm. For example, Si:H can have a refractive index greater than 3 in the wavelength range of 800 nm to 1700 nm. In some embodiments, the Si:H material has a refractive index greater than 3.5 (e.g., greater than 3.64) in the wavelength range of 800 nm to 1100 nm. In some embodiments, the Si:H material can have a refractive index of approximately 3.8 at a wavelength of approximately 830 nm. In some embodiments, the refractive index at 800 nm can be greater than 3.87. In some embodiments, the Si:H material has a refractive index less than 4.3 in the wavelength range of 800 nm to 1700 nm. The high-refractive-index layer may include phosphorus, boron, nitrides, argon, oxygen, carbides, etc.

[0034] In some embodiments, the second set of layers 440 may include a set of metal layers, and may be referred to herein as M layer 440. In some embodiments, M layer 440 may include silver. In some embodiments, each M layer 440 may be sandwiched between sets of H layers 430. In some embodiments, the optical filter coating portion 410 may include multiple sets of M layers 440 (e.g., a first M layer 440 sandwiched between a first pair of H layers 430 and a second M layer 440 sandwiched between a second pair of H layers 430). In some embodiments, H layers 430 may be disposed between two M layers 440. For example, a first H layer 430 and a second H layer 430 may sandwich a first M layer 440, while a second H layer 430 and a third H layer 430 may sandwich a second M layer 440. Additionally or alternatively, one or more intermediate layers may be disposed between a first set of H layers 430 sandwiching a first M layer 440 and a second set of H layers 430 sandwiching a second M layer 440.

[0035] In some embodiments, the third set of layers 450 may include a set of layers of low-refractive-index material (e.g., silicon dioxide or another material). For example, the refractive index of layer L 450 is typically lower than that of layer H 430. In this case, one or more alternating layers H 430 and L 450 can improve the performance of an optical filter comprising layers H 430 and M 440 by, for example, controlling one or more optical features of the optical filter.

[0036] The number, thickness, and / or order of layers can affect the optical quality (including optical transmission and angular displacement) of the optical filter coating portion 410 and / or the optical filter 400. In some embodiments, the optical filter coating portion 410 may be associated with a specific number (m) of layers. For example, the optical filter coating portion 410 may include 2 to 200 layers, 3 to 100 layers, or 5 to 21 layers. The optical filter coating portion 410 may include 3 H layers 430 to 40 H layers 430.

[0037] In some embodiments, each layer of the optical filter coating portion 410 may be associated with a specific thickness. For example, layers 430, 440, and / or 450 may each be associated with a thickness between 1 nm and 1500 nm, between 3 nm and 1000 nm, between 6 nm and 1000 nm, or between 10 nm and 500 nm, and / or the optical filter coating portion 410 may be associated with a thickness between 0.1 µm and 100 µm, between 0.25 µm and 20 µm, etc. In this case, layer M 440 may have a thickness between approximately 10 nm and approximately 60 nm. In some examples, at least one of layers 430, 440, and 450 may be associated with a thickness less than 1000 nm, less than 600 nm, less than 100 nm, or less than 20 nm, and / or the optical filter coating portion 410 may be associated with a thickness less than 100 µm, less than 50 µm, less than 10 µm, and / or less than 3 µm. In some embodiments, layers 430, 440, and / or 450 may be associated with multiple thicknesses (e.g., a first thickness of layer 430 and a second thickness of layer 440, a first thickness of a first subset of layers 430 and a second thickness of a second subset of layers 430, a first thickness of a first subset of layers 440 and a second thickness of a second subset of layers 440, etc.). In this case, the layer thickness and / or the number of layers may be selected based on a desired set of optical characteristics (e.g., a desired passband, a desired reflectivity, etc.).

[0038] In some embodiments, a specific SiGe-based material can be selected for the H layer 430. For example, in some embodiments, the H layer 430 can be selected and / or manufactured (e.g., via a sputtering process, as described further in detail below) to include a specific type of SiGe (e.g., SiGe-50, SiGe-40, SiGe-60, etc.). Additionally or alternatively, Si:H, SiGe-H, or Ge-H can be selected as the H layer 430.

[0039] In some embodiments, as described herein, the H layer 430 may include another material (e.g., argon) as a result of a sputtering deposition process. In another example, the H layer 430 may be fabricated using processes such as: hydrogenating a silicon- or SiGe-based material using a hydrogenation process; nitriding a silicon- or SiGe-based material using a nitriding process; annealing a silicon- or SiGe-based material using one or more annealing processes; using another type of process; doping a silicon- or SiGe-based material using a doping process (e.g., phosphorus-based doping, nitrogen-based doping, boron-based doping, etc.); or using a combination of processes (e.g., a combination of hydrogenation, nitriding, annealing, and / or doping), as described herein.

[0040] In some embodiments, the optical filter 400 may include a coating 480 on the side of the substrate opposite to the optical filter coating portion 410. The coating 480 may be a single layer or multiple layers. In some examples, the coating 480 may be an anti-reflective coating, a blocking filter, and / or a bandpass filter. The coating 480 may include at least one oxide (including SiOx, SiO2, TiO2, Ta2O5, etc.). In one example, the coating 480 may be an alternating layer of SiO2 and amorphous silicon. Additionally or alternatively, the coating 480 may have a structure similar to that of the optical filter coating portion 410 and may include two or more materials. In some embodiments, the material of the coating 480 may be selected to enable fabrication using a single sputtering deposition cycle (e.g., selecting silicon dioxide for sputtering using the same deposition cycle as that used for sputtering silicon hydride for the optical filter coating portion 410).

[0041] The optical filter coating portion 410 can be manufactured by any method (including, but not limited to, any coating and / or sputtering process). For example, the optical filter coating portion 410 shown can be manufactured by depositing an H layer 430 on a substrate 420, then depositing an M layer 440 on the H layer 430, and then depositing a second H layer 430 on the M layer 440. Subsequently, the same sputtering deposition process can be used to deposit one or more L layers 450, as described in more detail herein. This can be repeated until the desired number of layers are deposited. In some cases, other materials may be present in one or more of the layers 430, 440, 450, etc. For example, during the deposition process, the material used to form the deposited layer may diffuse into the underlying layer. In some embodiments, the optical filter coating portion 410 can be manufactured using a sputtering process. For example, the optical filter coating portion 410 can be manufactured on a substrate 420 using a pulsed magnetron-based sputtering process, which can be a glass substrate or another type of substrate.

[0042] In some embodiments, multiple cathodes (e.g., a first cathode for sputtering silicon and a second cathode for sputtering germanium) may be used in the sputtering process. In this case, the multiple cathodes may be associated with an angle of inclination of the first cathode relative to the second cathode, which is selected to ensure a specific concentration of germanium relative to silicon, as described below. In some embodiments, a hydrogen gas flow may be added during the sputtering process to hydrogenate the silicon or silicon-germanium. Similarly, a nitrogen gas flow may be added during the sputtering process to nitrid the silicon or silicon-germanium.

[0043] In some embodiments, the optical filter coating portion 410 may be annealed using one or more annealing processes (e.g., a first annealing process at approximately 280 degrees Celsius or at a temperature between approximately 200 degrees Celsius and approximately 400 degrees Celsius, a second annealing process at approximately 320 degrees Celsius or at a temperature between approximately 250 degrees Celsius and approximately 350 degrees Celsius, etc.). In some embodiments, the optical filter coating portion 410 may be fabricated using SiGe:H coated from a target material.

[0044] In some embodiments, the optical filter coating portion 410 is attached to a substrate, such as substrate 420. For example, the optical filter coating portion 410 may be attached to a glass substrate or another type of substrate. Additionally or alternatively, the optical filter coating portion 410 may be directly coated onto a detector or a set of silicon wafers including a detector array (e.g., using optical lithography, a lift-off process, etc.). In some embodiments, the optical filter coating portion 410 may be associated with an incident medium. For example, the optical filter coating portion 410 may be associated with an air medium or a glass medium as the incident medium. In some embodiments, the optical filter 400 may be disposed between a set of prisms. In another example, another incident medium (e.g., a transparent epoxy resin) and / or another substrate, such as a polymer substrate (e.g., a polycarbonate substrate, a cyclic olefin copolymer (COP) substrate, etc.), may be used.

[0045] In some embodiments, the optical filter 400 can have a low center wavelength shift with changes in the incident angle. As the incident angle changes from 0° to 60°, the center wavelength of the passband shifts in amplitude by less than 15 nm. In some examples, as the incident angle changes from 0° to 40°, the center wavelength of the passband can shift in amplitude by less than 5 nm.

[0046] As indicated above, Figure 4 is provided as an example only. Other examples may differ from those described with respect to Figure 4.

[0047] Figures 5A-5D are illustrations of one or more examples 500 of a sputtering deposition system for manufacturing one or more exemplary embodiments described herein.

[0048] As shown in Figure 5A, an exemplary sputtering deposition system may include a vacuum chamber 510, a substrate 520, a cathode 530, a target 531, a cathode power supply 540, an anode 550, a plasma activation source (PAS) 560, and a PAS power supply 570. The target 531 may include a specific concentration of silicon, silicon-germanium, etc., selected based on specific optical characteristics. In another example, the angle of the cathode 530 may be configured such that a specific concentration of silver, silicon, and / or silicon-germanium is sputtered onto the substrate 520, as described herein. The PAS power supply 570 may be used to power the PAS 560 and may include a radio frequency (RF) power supply. The cathode power supply 540 may be used to power the cathode 530 and may include a pulsed direct current (DC) power supply. In this case, the sputtering deposition system may allow one or more layers to be sputtered onto the substrate 520 via DC sputtering.

[0049] As shown in Figure 5A, the target 531 can be sputtered in the presence of hydrogen (H2) and an inert gas (e.g., argon) to deposit silver, silicon hydride (Si:H), silicon germanium hydride (SiGe:H), silicon dioxide (SiO2), or other materials as layers on the substrate 520. For example, the target 531 (and another target as described herein) can deposit alternating layers of silver and silicon hydride on a first side of the substrate 520 (e.g., to form an ITF bandpass filter), and alternating layers of silicon dioxide and silicon hydride on a second side of the substrate 520 (e.g., to control the optical properties of the ITF bandpass filter, as described above).

[0050] An inert gas can be supplied to the chamber via the anode 550 and / or PAS 560. Hydrogen is introduced into the vacuum chamber 510 via PAS 560 for hydrogen activation. Additionally or alternatively, the cathode 530 can induce hydrogen activation, in which case hydrogen can be introduced from another portion of the vacuum chamber 510, or the anode 550 can induce hydrogen activation, in which case the anode 550 can introduce hydrogen into the vacuum chamber 510. In some embodiments, hydrogen can be in the form of hydrogen gas, a mixture of hydrogen gas and an inert gas (e.g., argon), etc. PAS 560 can be located within a threshold close to the cathode 530, which allows plasma from PAS 560 and plasma from cathode 530 to overlap. The use of PAS 560 can allow for the deposition of Si:H layers and / or SiGe:H layers at relatively high deposition rates. In some embodiments, Si:H layers and / or SiGe:H layers are deposited at deposition rates 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 so on.

[0051] Although this paper describes the sputtering process with respect to a specific geometry and implementation, other geometries and other implementations are possible. For example, hydrogen can be injected from another direction, from a gas manifold near the threshold of cathode 530, etc.

[0052] As shown in Figures 5B-5C, a similar sputtering deposition system includes a vacuum chamber 510, a substrate 520, a first cathode 580, a second cathode 590, a first target 581, a second target 591, a cathode power supply 540, an anode 550, a PAS 560, and a PAS power supply 570. In this case, the first target 581 can be a silicon target, and the second target 591 can be a silver target. Therefore, as described herein, the first target 581 can be referred to as a silicon target, and the second target 591 can be referred to as a silver target. However, it should be understood that the first target 581 and / or the second target 591 can be made of other suitable materials to form a filter layer.

[0053] As shown in Figure 5B, the first target 581 (i.e., the silicon target) is oriented at approximately 0 degrees relative to the substrate 520 (e.g., approximately parallel to the substrate 520), while the second target 591 (i.e., the silver target) is oriented at approximately 120 degrees relative to the substrate 520. In this configuration, silicon and silver are sputtered onto the substrate 520 from the first target 581 (i.e., the silicon target) and the second target 591 (i.e., the silver target), respectively, by the first cathode 580 and the second cathode 590. In this configuration, using two targets, namely the first target 581 and the second target 591, allows for the fabrication of an ITF bandpass filter, such as the ITF bandpass filter 200, without requiring the vacuum provided by the sputtering deposition system to alter the target material, thus reducing manufacturing time.

[0054] As shown in Figure 5C, in a similar sputtering deposition system, the first target 581 (i.e., silicon target) and the second target 591 (i.e., silver target) are each oriented at approximately 60 degrees relative to the substrate 520, and silicon and silver are sputtered onto the substrate 520 from the first target 581 (i.e., silicon target) and the second target 591 (i.e., silver target) by the first cathode 580 and the second cathode 590, respectively.

[0055] As shown in Figure 5D, in a similar sputtering deposition system, the first target 581 (i.e., the silicon target) is oriented at approximately 120 degrees relative to the substrate 520, while the second target 591 (i.e., the silver target) is oriented at approximately 0 degrees relative to the substrate 520. In this case, silicon and germanium are sputtered onto the substrate 520 from the first target 581 (i.e., the silicon target) and the second target 591 (i.e., the silver target) by the first cathode 580 and the second cathode 590, respectively.

[0056] Regarding Figures 5A-5D, each configuration of the components in the silicon sputtering deposition system can result in different relative concentrations of silicon, silicon, and silver, etc. Although this article describes different component configurations, different relative concentrations of silicon and germanium can also be achieved using different materials, different manufacturing processes, etc.

[0057] As shown above, Figures 5A-5D are provided only as one or more examples. Other examples may differ from what is described regarding Figures 5A-5D.

[0058] Figures 6A-6B are illustrations of one or more exemplary embodiments 600 described herein. As shown in Figure 6A, exemplary embodiment 600 may include a sensor system 610. The sensor system 610 may be part of an optical system and may provide an electrical output corresponding to sensor determination. The sensor system 610 includes an optical filter structure 620 and an optical sensor 640, the optical filter structure 620 including an optical filter 630. For example, the optical filter structure 620 may include an optical filter 630 performing a passband filtering function or another type of optical filter. The sensor system 610 includes an optical transmitter 650 that emits optical signals to a target 660 (e.g., a person, object, etc.).

[0059] Although the embodiments described herein can be based on optical filters in a sensor system, the embodiments described herein can be used in another type of system, can be used outside the sensor system, etc.

[0060] As further shown in Figure 6A, and marked by symbols, the input optical signal 670 is directed to the optical filter structure 620. The input optical signal may include NIR light emitted by the optical emitter 650 and ambient light from the environment in which the sensor system 610 is used. For example, when the optical filter 630 is a bandpass filter, the optical emitter 650 may direct near-infrared (NIR) light toward the user of a gesture recognition system (e.g., a gesture performed by the target object 660), and the NIR light may be reflected from the target object 660 (e.g., the user) toward the optical sensor 640 to allow the optical sensor 640 to perform NIR light measurements. In this case, ambient light may be directed toward the optical sensor 640 from one or more ambient light sources (e.g., a light bulb or the sun). In another example, multiple beams may be directed toward the target object 660, and a subset of the multiple beams may be reflected toward the optical filter structure 620, which may be positioned at an angle relative to the optical sensor 640, as shown. In some implementations, another tilt angle may be used (e.g., a 0-degree tilt angle for a bandpass filter).

[0061] In some embodiments, the optical filter structure 620 may be directly disposed and / or formed on the optical sensor 640, rather than being disposed at a distance from the optical sensor 640. For example, the optical filter structure 620 may be coated and patterned onto the optical sensor 640 using, for example, optical lithography. In another example, the optical emitter 650 may direct NIR light toward another type of target 660 (e.g., for detecting objects near vehicles, detecting objects near blind people, detecting object proximity (e.g., using LiDAR technology), etc.), and as a result, may direct both NIR light and ambient light toward the optical sensor 640.

[0062] As further shown in Figure 6A, and marked by symbols, a portion of the optical signal 680 passes through the optical filter 630 and the optical filter structure 620. For example, the optical filter 630 may include any optical filter coating portion 410 of the aforementioned optical filter 400, and may cause a portion of the light to be reflected in the first direction. In this case, the optical filter 630 blocks the visible light of the input optical signal without excessively blocking NIR light, and does not introduce excessive angular displacement as the incident angle of the input optical signal increases.

[0063] As further shown in Figure 6A, and marked by symbols, based on the portion of the optical signal transmitted to the optical sensor 640, the optical sensor 640 can provide an output electrical signal 690 to the sensor system 610 (e.g., for recognizing a user's gesture or detecting the presence of an object). In some embodiments, alternative arrangements of the optical filter 630 and the optical sensor 640 may be used. For example, the optical filter 630 may direct a second portion of the optical signal in a different direction to the optical sensor 640 at a different location, rather than allowing the second portion of the optical signal to pass through collinearly with the input optical signal. In another example, the optical sensor 640 may be an avalanche photodiode, an indium gallium arsenide (InGaAs) detector, an infrared light detector, etc.

[0064] As shown in Figure 6B, a similar exemplary embodiment 600 may include a sensor system 610, an optical filter structure 620, an optical filter 630, an optical sensor 640, an optical emitter 650, and a target 660. Figure 6B illustrates a specific exemplary embodiment 600 including the optical filter 630 as described herein.

[0065] Optical emitter 650 emits light with a wavelength range of 800 nm to 1100 nm. Optical emitter 650 emits modulated light (e.g., light pulses). Optical emitter 650 can be a light-emitting diode (LED), an LED array, a laser diode, or a laser diode array. Optical emitter 650 emits light toward a target object 660, which reflects the emitted light back to sensor system 610. When sensor system 610 is a gesture recognition system, target object 660 is a user of the gesture recognition system. Sensor system 610 can also be a proximity sensor system, a three-dimensional (3D) imaging system, a distance sensor system, a depth sensor, and / or another suitable sensor system.

[0066] Optical filter 630 is configured to receive light emitted after reflection from target 660. Optical filter 630 has a passband that includes the emitted wavelength and at least partially overlaps with a wavelength range of 800 nm to 1100 nm. Optical filter 630 is a bandpass filter (e.g., an ITF bandpass filter). Optical filter 630 transmits light emitted from optical emitter 650 while substantially blocking ambient light.

[0067] Optical sensor 640 is configured to receive emitted light transmitted by optical filter 630. In some embodiments, optical filter 630 is formed directly on optical sensor 640. For example, optical filter 630 can be coated and patterned (e.g., by optical lithography) on a sensor (e.g., a proximity sensor) in wafer-level processing (WLP).

[0068] When the sensing system 610 is a proximity sensing system, the optical sensor 640 is a proximity sensor that detects emitted light to sense the approach of the target 660. When the sensing system 610 is a 3D imaging system or a gesture recognition system, the optical sensor 640 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 660, such as a user. The 3D image sensor converts optical information into electrical signals for processing by a processing system (e.g., an application-specific integrated circuit (ASIC) chip or a digital signal processor (DSP) chip). When the sensing system 610 is a gesture recognition system, the processing system processes a 3D image of the user to recognize the user's gestures. Other types of sensing systems 610 may be possible.

[0069] As shown above, Figures 6A-6B are provided merely as one or more examples. Other examples may differ from what is described regarding Figures 6A-6B.

[0070] Figure 7 is a flowchart of an exemplary process 700 associated with the fabrication of an ITF bandpass filter using silicon hydride and silver. In some embodiments, one or more process blocks of Figure 7 may be performed by a fabrication apparatus (e.g., the sputtering deposition system of Figures 5A-5D).

[0071] As shown in Figure 7, process 700 may include depositing a first subset of optical filter layers of an optical filter, the first subset of which includes a first material having a first refractive index, the first material including at least silicon and hydrogen (block 710). For example, as described above, the manufacturing apparatus may deposit a first subset of optical filter layers of an optical filter, the first subset of which includes a first material having a first refractive index, the first material including at least silicon and hydrogen.

[0072] As further shown in Figure 7, process 700 may include depositing a second subset of an optical filter layer of an optical filter, the second subset of the optical filter layer including a second material having a second refractive index, the second material being different from the first material and having a second refractive index less than the first refractive index, the second material including at least silver (block 720). For example, as described above, the manufacturing apparatus may deposit a second subset of an optical filter layer of an optical filter, the second subset of the optical filter layer including a second material having a second refractive index, the second material being different from the first material, and the second material including at least silver.

[0073] Process 700 may include additional implementations (such as any single implementation or any combination of implementations of one or more other processes described below and / or described elsewhere herein).

[0074] In a first embodiment, the first subset of deposited optical filter layers includes the first subset of optical filter layers sputtered using a first target.

[0075] In the second embodiment, either alone or in combination with the first embodiment, the second subset of deposited optical filter layers includes a second subset of optical filter layers sputtered using a second target.

[0076] In the third embodiment, either alone or in combination with one or more of the first and second embodiments, process 700 includes depositing a third subset of optical filter layers of optical filters, the third subset of optical filter layers including a third material having a third refractive index.

[0077] In the fourth embodiment, the material is silicon hydride (SiH), silver (Ag), and silicon dioxide (SiO2), either alone or in combination with one or more of the materials in the first to third embodiments.

[0078] In the fifth embodiment, a third subset of the optical filter layer is deposited, either alone or in combination with one or more of the first to fourth embodiments. At least one of a first target for depositing a first subset of the optical filter layer or a second target for depositing a second subset of the optical filter layer is used.

[0079] In the sixth embodiment, an optical filter is manufactured using a single vacuum chamber, either alone or in combination with one or more of the first to fifth embodiments.

[0080] Although Figure 7 shows an example block for process 700, in some implementations, process 700 may include additional blocks, fewer blocks, different blocks, or blocks arranged differently compared to those depicted in Figure 7. Additionally or alternatively, two or more blocks of process 700 may be executed in parallel.

[0081] The foregoing disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations can be made based on the foregoing disclosure, or can be obtained from practice of the embodiments.

[0082] As used in this article, depending on the context, satisfying the threshold can mean that the value is greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, etc., which depends on the context.

[0083] Even though specific combinations of features are described in the request and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various embodiments. In fact, many of these features can be combined in ways not specifically described in the request and / or disclosed in the specification. Although each dependent request listed below may directly depend on only one request, the disclosure of various embodiments includes combinations of each dependent request with every other request in the set of requests.

[0084] Unless explicitly stated otherwise, no element, action, or instruction used herein should be construed as essential or necessary. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items and may be used interchangeably with “one or more.” Furthermore, as used herein, the article “the” is intended to include one or more items mentioned in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.) and may be used interchangeably with “one or more.” Where the intent is for only one item, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “has,” “have,” “having,” or similar terms are intended to be open-ended terms. Furthermore, the phrase “based on” is intended to mean “at least partially based on,” unless explicitly stated otherwise. Furthermore, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and / or” unless otherwise expressly stated (e.g., if used in combination with “any” or “only one of…”).

[0085] 100: ITF bandpass filter 150: ITF bandpass filter 200: ITF bandpass filter 300: ITF bandpass filter 310: ITF bandpass filter 320: ITF bandpass filter 330: ITF bandpass filter 400: Optical filter 410: Optical filter coating section 420:Substrate 430: Layer / H layer 440: Layer / M layer 450: layers / L layers 480: Coating 500: Example 510: Vacuum Chamber 520:Substrate 530: Cathode 531: Target Material 540: Cathode Power Supply 550: Anode 560: Plasma Activator (PAS) 570: PAS Power Supply 580: First cathode 581: First target material 590: Second cathode 591: Second target material 600: Implementation Method 610: Sensor System 620: Optical filter structure 630: Optical Filter 640: Optical Sensor 650: Optical transmitter 660: Target 670: Input optical signal 680: Partial optical signal 690: Output electrical signal 700: Process 710: Square 720: Square

Claims

1. An induced transmission filter, the induced transmission filter comprising: An assembly of optical filter layers, the assembly of optical filter layers comprising: a first subset of optical filter layers, the first subset of optical filter layers comprising at least one of the following materials: silicon hydride (Si:H) material, amorphous silicon (a-Si) material, silicon germanium (SiGe) material, or silicon germanium hydride (SiGe:H) material; a second subset of optical filter layers, the second subset of optical filter layers comprising silver, wherein a layer of the first subset of optical filter layers is sandwiched between a pair of layers of the second subset of optical filter layers without an interlayer; and a third subset of optical filter layers, the third subset of optical filter layers comprising silicon dioxide (SiO2).

2. The induced transmission filter according to claim 1, wherein, Another layer of the first subset of the optical filter layers is sandwiched between a pair of layers of the third subset of the optical filter layers without an intermediary layer.

3. The induced transmission filter according to claim 1, wherein, The first subset of the optical filter layer has a refractive index greater than 3 in the wavelength range from 800 nm to 1700 nm.

4. The induced transmission filter according to claim 1, wherein, The first subset of the optical filter layer has a refractive index greater than 3.5 in the wavelength range from 800 nm to 1100 nm.

5. The induced transmission filter according to claim 1, wherein, At a wavelength of approximately 830 nanometers, the refractive index of the first subset of the optical filter layer is greater than 3.

8.

6. The induced transmission filter according to claim 1, wherein, At a wavelength of approximately 800 nanometers, the refractive index of the first subset of the optical filter layer is greater than 3.

87.

7. The induced transmission filter according to claim 1, wherein, The refractive index of the first subset of the optical filter layer is greater than the refractive index of the third subset of the optical filter layer.

8. A method for manufacturing an optical filter, the method comprising: The optical filter layer of the optical filter is deposited in a first subset, the first subset comprising at least one of the following: silicon hydride (Si:H) material, amorphous silicon (a-Si) material, silicon germanium (SiGe) material, or silicon germanium hydride (SiGe:H) material; a second subset comprising silver (Ag) is deposited, wherein one layer of the first subset is sandwiched between a pair of layers of the second subset without an interlayer; and a third subset comprising silicon dioxide (SiO2) is deposited.

9. The method according to claim 8, wherein, Another layer of the first subset of the optical filter layers is sandwiched between a pair of layers of the third subset of the optical filter layers without an intermediary layer.

10. The method according to claim 8, wherein, The first subset of the optical filter layer has a refractive index greater than 3 in the wavelength range from 800 nm to 1700 nm.

11. The method according to claim 8, wherein, The first subset of the optical filter layer has a refractive index greater than 3.5 in the wavelength range from 800 nm to 1100 nm.

12. The method according to claim 8, wherein, At a wavelength of approximately 830 nanometers, the refractive index of the first subset of the optical filter layer is greater than 3.

8.

13. The method according to claim 8, wherein, At a wavelength of approximately 800 nanometers, the refractive index of the first subset of the optical filter layer is greater than 3.

87.

14. The method according to claim 8, wherein, The refractive index of the first subset of the optical filter layer is greater than the refractive index of the third subset of the optical filter layer.

15. An optical system comprising: An optical filter for filtering an input optical signal and providing a filtered input optical signal, the optical filter comprising: a set of optical filter layers, including: a first subset of optical filter layers comprising a first material, the first material comprising at least one of: silicon hydride (Si:H) material, amorphous silicon (a-Si) material, silicon germanium (SiGe) material, or silicon germanium hydride (SiGe:H) material; and a second subset of optical filter layers comprising a second material, wherein one layer of the first subset of optical filter layers is directly deposited on the first layer of the second subset of optical filter layers. The second layer of the second subset of the optical filter layer is deposited directly on the layer of the first subset of the optical filter layer, and the first material includes at least silver; and the third subset of the optical filter layer includes a third material, the third material including silicon dioxide (SiO2); and the optical receiver is used to receive the filtered input optical signal and provide an output electrical signal.

16. The optical system according to claim 15, wherein, Another layer of the first subset of the optical filter layers is deposited directly on the first layer of the third subset of the optical filter layers, and the second layer of the third subset of the optical filter layers is deposited directly on the other layer of the first subset of the optical filter layers.

17. The optical system according to claim 15, wherein, The optical filter includes: a substrate; and another set of optical filter layers, wherein the set of optical filter layers is disposed on a first side of the substrate and the other set of optical filter layers is disposed on a second side of the substrate.

18. The optical system according to claim 15, wherein, The optical filter includes: a substrate; and a coating, wherein an assembly of optical filter layers is disposed on a first side of the substrate and the coating is disposed on a second side of the substrate.

19. The optical system according to claim 15, wherein, With a center wavelength of approximately 820 nanometers, the optical filter has an angular displacement of 8.1 nanometers at an incident angle of 40 degrees.

20. The optical system according to claim 15, wherein, With a center wavelength of approximately 820 nanometers, the optical filter has a transmittance of 65%-70% at the center wavelength.

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