Inductive transmission filter

Abstract

To provide an induced transmission filter (ITF) bandpass filter which offers reduced angle shift and improved transmissivity.SOLUTION: An induced transmission filter provided herein comprises a set of optical filters. The set of optical filters includes a first subset of optical filter layers comprising a first material with a first refractive index, where the first material may comprise at least silicon and hydrogen. The set of optical filters includes a second subset of optical filter layers comprising a second material with 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 include at least silver.SELECTED DRAWING: Figure 2B

Description

Technical Field

[0001] Cross - reference to Related Applications This patent application claims priority to U.S. Provisional Patent Application No. 63 / 016,731, filed Apr. 28, 2020, entitled "Inductive Transmission Filter Comprising Hydrogenated Silicon and Silver". The disclosure of the prior application is considered a part of this patent application and is incorporated herein by reference.

Background Art

[0002] An optical transmitter can emit light towards one or more objects. For example, in a gesture recognition system, an optical transmitter can transmit near - infrared (NIR) light towards a user, and the NIR light may be reflected from the user. In this case, an optical receiver can capture information regarding the NIR light, and the information can be used to recognize the gesture being performed by the user. For example, a device can use the information to generate a three - dimensional representation of the user and, based on the three - dimensional representation, identify the gesture being performed by the user. In other examples, a system can use an optical transmitter and an optical receiver for ranging, object recognition, spectroscopy, health monitoring, and / or the like.

[0003] In some cases, during the transmission of light, a particular pattern of the transmitted light, or a band of the transmitted light, may be desired, and thus, an optical shaping element may be disposed in the optical path between the optical transmitter and the target. Similarly, during the transmission of light towards the target and / or during the reflection from the target, ambient light may interfere with the transmitted light at the optical receiver. In such cases, an optical filter may be disposed in the optical path between the target and the optical receiver. For example, an optical receiver may be optically coupled to an inductive transmission filter, a band - pass filter, and / or the like to filter out light of a certain wavelength (e.g., a wavelength corresponding to ambient light) and allow light of other wavelengths (e.g., a wavelength corresponding to, for example, the transmitted NIR light) to pass towards the optical receiver.

Summary of the Invention

[0004] According to some possible embodiments, the inductive transmitting filter may include a set of optical filter layers. The set of optical filter layers includes a first subset of optical filter layers comprising a first material having a first refractive index, the first material may comprise 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 may be different from the first material, the second material may comprise at least silver.

[0005] In some possible embodiments, the method may include: depositing a first subset of the optical filter layer of an optical filter, wherein the first subset of the optical filter layer comprises a first material having a first refractive index, and the first material comprises at least silicon and hydrogen; depositing a second subset of the optical filter layer of an optical filter, wherein the second subset of the optical filter layer comprises a second material having a second refractive index, wherein the second material differs from the first material, and the second material comprises at least a metal. The metal may be silver.

[0006] According to some possible embodiments, the optical system may include an optical filter for filtering an input optical signal to provide a filtered input optical signal. The optical filter may include a set of optical filter layers. The set of optical filter layers includes a first subset of optical filter layers comprising a first material having a first refractive index, the first material may comprise at least silicon and hydrogen. The set of optical filter layers includes a second subset of optical filter layers comprising a second material having a second refractive index, the second material differing from the first material, the second material may comprise at least silver. The optical system may include an optical receiver for receiving the filtered input optical signal and providing an output electrical signal. [Brief explanation of the drawing]

[0007] [Figure 1] Figures 1A to 1F illustrate exemplary inductive transmission filters in various embodiments described herein. [Figure 2] Figures 2A to 2D illustrate examples related to inductive transmission filters in various embodiments described herein. [Figure 3] Figures 3A to 3D illustrate examples related to inductive transmission filters in various embodiments described herein. [Figure 4] This figure shows an example related to one set of optical filter layers of an inductive transmit filter in various embodiments described herein. [Figure 5] Figures 5A to 5D illustrate examples related to a sputtering system for depositing a set of optical filter layers in various embodiments described herein. [Figure 6] Figures 6A and 6B illustrate examples related to optical systems including inductive transmit filters in various embodiments described herein. [Figure 7] This is a flowchart of exemplary steps related to the manufacture of an inductive transmitting filter in various embodiments described herein. [Modes for carrying out the invention]

[0008] A detailed description of the following exemplary embodiments is provided with reference to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements. The following description uses optical systems, such as gesture recognition systems, spectrometers, or health monitoring systems, among other examples. However, the techniques, principles, procedures, and methods described herein can be used with any sensor, including but not limited to other optical sensors and spectroscopic sensors.

[0009] An optical receiver can receive light from a light source, such as an optical transmitter. For example, an optical receiver may receive near-infrared (NIR) light from an optical transmitter and reflect it off a target. Alternatively, the optical receiver may receive other bands of light without reflecting them off a target, in other examples such as ranging applications or communication applications. The target may include people (e.g., users and non-users), animals, inanimate objects (e.g., cars and other vehicles, trees, obstacles, furniture, walls) and / or similar objects. The optical receiver may receive light from an optical transmitter or ambient light such as visible spectrum light. Ambient light may include light from one or more light sources isolated from the optical transmitter, such as sunlight or light from a light bulb.

[0010] Ambient light can reduce the accuracy of decisions regarding transmitted light. For example, in a gesture recognition system, ambient light can reduce the accuracy of generating a 3D image of a target using NIR light. In several other examples, information about NIR light may be used to recognize user identity, user characteristics (e.g., height or weight), user state (e.g., position of the user's eyelids, whether the user is awake, and / or similar), other types of target characteristics (e.g., distance to an object, size of an object, or shape of an object), and / or similar. In such examples, the presence of ambient light or light of unintended wavelengths can reduce the accuracy of decisions made using information from the optical receiver. Therefore, the optical receiver may optionally be optically coupled to an optical filter, such as a bandpass filter, to filter out ambient light and allow NIR light to pass through to the optical receiver. In some embodiments, this is described as an optical filter coupled to the optical receiver, but in other embodiments, it may be applicable to photoforming and filtering optical elements coupled to the optical receiver.

[0011] Figures 1A to 1F are diagrams illustrating examples of inductive transmission filters.

[0012] As shown in Figure 1A, the inductive transmit 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., titanium niobium oxide (NbTiOx)). The first and second materials may be selected to achieve out-of-band blocking in a specific spectral range. In other words, the first and second materials (as well as the number and thickness of their layers) allow the first band of light to pass through and block the second band of light, thereby enabling sensing of the first band of light without negative performance caused by unintended wavelengths in the second band of light. For some sensing applications, silver may be selected as the first material and an oxide (NbTiOx as shown) as the second refractive material. However, silver can react with oxides, which can negatively impact the optical properties of filters containing silver and oxides. The addition of a buffer layer such as zinc oxide (ZnO) can reduce the reactivity between silver and the oxide. As shown in Figures 1B and 1C, the IFT bandpass filter 100 may have a transmittance of approximately 40-45% 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 1B, there may be leakage (unintended transmittance) at the first harmonic of the center wavelength of the IFT bandpass filter 100 (for example, between approximately 400 nm and 470 nm), which may result in insufficient optical performance.

[0013] As shown in Figures 1D to 1F, further addition of dielectric stacks of high refractive index materials (fourth material) such as amorphous silicon (a-Si) and low refractive index materials (fifth material) such as silicon dioxide (SiO2) may further improve the optical performance of the ITF bandpass filter 150 containing silver and oxides. For example, as shown in Figures 1E and 1F, the ITF bandpass filter 150 may have a transmittance of about 53%, eliminate the leakage (unintended transmittance) at about 450 nm that occurs with respect to the ITF bandpass filter 100, and slightly reduce the angular shift at a 60-degree incident angle to 40 nm.

[0014] As mentioned above, Figures 1A to 1F are provided as examples. Other examples may differ from those described in relation to Figures 1A to 1F.

[0015] However, the use of a third, fourth, and fifth material can make the manufacture of optical filters difficult. For example, some deposition systems limit the number of materials that can be deposited to two or fewer, or three or fewer. Therefore, manufacturing optical filters containing three, four, five, or more materials requires multiple deposition processes, which can be costly and time-consuming. Furthermore, the aforementioned optical filters may have relatively large angular shifts.

[0016] Therefore, some embodiments described herein may utilize, for example, non-oxide materials paired with silver in the ITF bandpass filter. For example, the ITF bandpass filter may include, among other examples, a first set of silver layers and a second set of layers of, for example, silicon hydride (Si;H), silicon germanium hydride (SiGe-H), or germanium hydride (Ge-H). By replacing the oxide layer with, for example, silicon hydride, the need for a protective layer (for example, ZnO) to avoid reactivity between silver and oxide is eliminated. Furthermore, since silicon hydride can be sputtered from a silicon target which silicon dioxide can also be sputtered, an ITF bandpass filter including, for example, amorphous silicon, silver, and silicon dioxide layers may be sputtered using a single sputtering process. Moreover, ITF bandpass filters manufactured using silver, silicon hydride, and silicon dioxide may achieve reduced angular shift and improved transmission rate compared to the ITF bandpass filters 100 and 150 described above.

[0017] Figures 2A to 2D are examples related to ITF bandpass filters.

[0018] As shown in Figure 2A, the ITF bandpass filter 200 may include alternating layers of silver and amorphous silicon, as well as a dielectric stack formed from alternating layers of silicon dioxide and amorphous silicon. In this case, as shown in Figures 2B-2D, the ITF bandpass filter 200 at a central wavelength of approximately 820 nm achieves improved transmission efficiency (e.g., greater than 60% at the central wavelength, between approximately 65-70%) and reduced angular shift (e.g., reduced from 26 nm to 8.1 nm at an incident angle of 40 degrees) compared with the ITF bandpass filters 100 and 150. Furthermore, the ITF bandpass filter 200 suppresses the aforementioned leakage at 450 nm, thereby improving optical performance compared with the IFT bandpass filter 100. In this way, by using amorphous silicon, for example, instead of an oxide layer paired with silver, the number of materials is reduced and optical performance is improved, thereby improving manufacturability, as will be 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 (thickness 1265.6 nm), thereby enabling improved miniaturization of optical systems, cost reduction, and / or similar effects.

[0019] As mentioned above, Figures 2A to 2D are provided as examples. Other examples may differ from those described with respect to Figures 2A to 2D. The number and arrangement of devices shown in Figures 2A to 2D are provided as examples.

[0020] Figures 3A to 3D are examples related to ITF bandpass filters.

[0021] As shown in FIG. 3A, the ITF bandpass filter 300 may be configured to achieve a low angle shift at a central wavelength of 950 nm (and with collimated light). The ITF bandpass filter 300 may include a coating of a filter layer with a thickness of 1.96 micrometers (μm) on the first side of the substrate and a coating of a filter layer with a thickness of 1.1 μm on the second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 300 may be between about 22.3 nm and 22.7 nm, and the angle shift may be about 3.2 nm (-3.2 nm with respect to the central wavelength) at an incident angle of 40 degrees. As shown in FIG. 3B, the ITF bandpass filter 310 may be configured to achieve a low angle shift at a central wavelength of 940 nm (and with collimated light). The ITF bandpass filter 310 may include a coating of a filter layer with a thickness of 2.25 μm on the first side of the substrate and a coating of a filter layer with a thickness of 1.15 μm on the second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 310 may be between about 20.5 nm and 23.3 nm, and the angle shift may be about 10.0 nm (-10.0 nm with respect to the central wavelength) at an incident angle of 40 degrees.

[0022] As shown in FIG. 3C, the ITF bandpass filter 320 may be configured to achieve a low angle shift at a central wavelength of 940 nm (and with collimated light), but with a narrower bandwidth compared to the ITF bandpass filters 300 and 310. The ITF bandpass filter 320 may include a coating of a filter layer with a thickness of 2.25 μm on the first side of the substrate and a coating of a filter layer with a thickness of 1.15 μm on the second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 320 may be between about 16.3 nm and 18.5 nm, and the angle shift may be about 7.95 nm (-7.95 nm with respect to the central wavelength) at an incident angle of 40 degrees. As shown in FIG. 3D, the ITF bandpass filter 330 may be configured to achieve a low angle shift at a central wavelength of 1550 nm (and with collimated light). The ITF bandpass filter 330 may include a coating of a filter layer with a thickness of 4.4 μm on the first side of the substrate and a coating of a filter layer with a thickness of 2.3 μm on the second side of the substrate. In this case, the bandwidth of the ITF bandpass filter 330 may be between about 40.0 nm and 45.5 nm, and the angle shift may be about 7.46 nm (-7.46 nm with respect to the central wavelength) at an incident angle of 40 degrees.

[0023] As described above, FIGS. 3A-3D are provided as examples. Other examples may be different from those described with respect to FIGS. 3A-3D. The number and arrangement of the devices shown in FIGS. 3A-3D are provided as examples.

[0024] FIG. 4 is a diagram of an example of an optical filter 400. As further shown in FIG. 4, the optical filter 400 may include an optical filter coating portion 410 and a substrate 420.

[0025] As shown in Figure 4, the optical filter coating section 410 includes a set of optical filter layers. For example, the optical filter coating section 410 includes a first set of layers 430, a second set of layers 440, and in some embodiments, a third set of layers 450. The first set of layers 430 may include a set of layers of high refractive index material, which is here referred to as the H layer 430. For example, in some embodiments, the H layer 430 may include a material containing hydrogen and silicon (e.g., a silicon hydride (Si:H) layer that may contain silicon (Si) and hydrogen (H), a silicon hydride-germanium (SiGe:H) layer, and / or the like). In some embodiments, the H layer 430 may include a material containing silicon and germanium (e.g., a silicon-germanium (SiGe) layer, and / or the like).

[0026] These high refractive index materials may have refractive indices higher than 3, 3.2, 3.5, 3.6, 4, and / or similar values ​​over a wavelength range of at least 800 nanometers (nm) to 1700 nm. For example, Si:H may have a refractive index greater than 3 over a wavelength range of 800 nm to 1700 nm. In some embodiments, the Si:H material has a refractive index greater than 3.5 over a wavelength range of 800 nm to 1100 nm (for example, a refractive index greater than 3.64). In some embodiments, the Si:H material may have a refractive index of about 3.8 at a wavelength of about 830 nm. In some embodiments, the refractive index may be greater than 3.87 at 800 nm. In some embodiments, the Si:H material has a refractive index of less than 4.3 over a wavelength range of 800 nm to 1700 nm. The high refractive index layer may contain phosphorus, boron, nitrides, argon, oxygen, carbides, and / or similar.

[0027] In some embodiments, the second set of layers 440 may include a set of metal layers, which are hereby referred to as M layers 440. In some embodiments, the M layers 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 (for example, 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, the H layers 430 may be placed between two M layers 440. For example, the first H layer 430 and the second H layer 430 may sandwich the first M layer 440, and the second H layer 430 and the third H layer 430 may sandwich the second M layer 440. Furthermore, or alternatively, one or more intermediate layers may be placed between a first set of H layers 430 flanking the first M layer 440 and a second set of H layers 430 flanking the second M layer 440.

[0028] In some embodiments, a third set of layers 450 may include a low refractive index material layer, such as silicon dioxide or another material. For example, the refractive index of the L layer 450 is generally lower than that of the H layer 430. In this case, one or more alternating H layers 430 and L layers 450 may improve the performance of the optical filter including the H layer 430 and M layer 440, for example, by controlling one or more optical properties of the optical filter.

[0029] The number, thickness, and / or order of the layers may affect the optical quality of the optical filter coating section 410 and / or the optical filter 400, including optical transmission and angular shift. In some embodiments, the optical filter coating section 410 may be associated with a specific number of layers, m. For example, the optical filter coating section 410 may include 2 to 200 layers, 3 to 100 layers, or 5 to 21 layers. The optical filter coating section 410 may include 3 to 40 H layers 430.

[0030] In some embodiments, each layer of the coating portion 410 of the optical filter may be associated with a specific thickness. For example, layers 430, 440 and / or 450 may be associated with thicknesses 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 thicknesses between 0.1 μm and 100 μm, between 0.25 μm and 20 μm, and / or similar. In this case, layer M 440 may have a thickness between approximately 10 nm and 60 nm. In some examples, at least one of layers 430, 440, and 450 may 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 the optical filter coating portion 110 may be associated with a thickness of 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 layer 450 may be associated with multiple thicknesses, such as a first thickness of layer 430 and a second thickness of layer 440, a first thickness of a first subset of layer 430 and a second thickness of a second subset of layer 430, a first thickness of a first subset of layer 440 and a second thickness of a second subset of layer 440, and / or the like. In this case, the thickness of the layers and / or the number of layers may be selected based on a set of intended optical properties, such as an intended passband, intended reflectance, and / or the like.

[0031] In some embodiments, a specific SiGe-based material may be selected for the H layer 430. For example, in some embodiments, the H layer 430 may be selected to include a specific type of SiGe such as SiGe-50, SiGe-40, SiGe-60 and / or similar, and / or may be manufactured (for example, via a sputtering process, as will be described in more detail below). Furthermore, or instead, Si:H, SiGe-H, or Ge-H may be selected for the H layer 430.

[0032] In some embodiments, the H layer 430 may contain other materials, such as argon, as a result of the sputter deposition process as described herein. In other examples, the H layer 430 may be produced using a hydrogenation process for hydrogenating a silicon or SiGe-based material, a nitrogenation process for nitrogenizing a silicon or SiGe-based material, one or more annealing processes for annealing a silicon or SiGe-based material, a doping process for doping a silicon or SiGe-based material (e.g., phosphorus-based doping, nitrogen-based doping, boron-based doping, and / or similar), or a combination of several processes (e.g., a combination of hydrogenation, nitrogenation, annealing, and / or doping as described herein).

[0033] In some embodiments, the optical filter 400 may include a coating 480 on the opposite side of the substrate from 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 is made of SiO x The coating may contain at least one oxide, including SiO2, TiO2, Ta2O5, and / or similar. In one example, the coating 480 may be alternating layers of SiO2 and amorphous silicon. Furthermore, or alternatively, the coating 480 may have a similar structure to the optical filter coating 410 and may contain more than two materials. In some embodiments, the material for the coating 480 may be selected to enable production using a single sputter deposition cycle, such as selecting silicon dioxide for sputtering using the same deposition cycle used to sputter silicon hydride for the optical filter coating 410.

[0034] 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 may be manufactured by depositing an H layer 430 on a substrate 420, then depositing an M layer 440 on top of the H layer 430, and then depositing a second H layer 430 on top of the M layer 440. Subsequently, the same sputtering deposition procedure may be used to deposit one or more L layers 450, as will be described in more detail herein. This may be repeated until the desired number of layers are deposited. In some cases, one or more other materials may be present in the layers 430, 440, 450, and / or similar. For example, during the deposition process, the material used to form the deposited layers may bleed into the underlying layers. In some embodiments, the optical filter coating portion 410 may be manufactured using a sputtering procedure. For example, the optical filter coating portion 410 may be manufactured using a pulsed magnetron-based sputtering procedure on a substrate 420, which may be a glass substrate or another type of substrate.

[0035] In some embodiments, multiple cathodes, such as a first cathode for sputtering silicon and a second cathode for sputtering germanium, may be used for the sputtering procedure. In this case, the multiple cathodes may be associated with an inclination angle of the first cathode to the second cathode, selected to ensure a specific concentration of germanium relative to silicon, as described below. In some embodiments, a hydrogen stream may be added during the sputtering procedure for hydrogenating silicon or silicon-germanium. Similarly, a nitrogen stream may be added during the sputtering procedure for nitrogenating silicon or silicon-germanium.

[0036] In some embodiments, the optical filter coating portion 410 may be annealed using one or more annealing procedures, such as a first annealing procedure at a temperature of approximately 280 degrees Celsius or between approximately 200 and approximately 400 degrees Celsius, a second annealing procedure at approximately 320 degrees Celsius or between approximately 250 and approximately 350 degrees Celsius, and / or similar. In some embodiments, the optical filter coating portion 410 may be manufactured using SiGe:H coated from a target.

[0037] In some embodiments, the optical filter coating portion 410 may be mounted on a substrate such as a substrate 420. For example, the optical filter coating portion 410 may be mounted on a glass substrate or other type of substrate. Furthermore, or alternatively, the optical filter coating portion 410 may be coated directly on the detector or on a set of silicon wafers containing the array of detectors (for example, using photolithography, a lift-off process, and / or similar). 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 one embodiment, the optical filter 400 may be placed between a pair of prisms. In other examples, other incident mediums such as transparent epoxy may be used, and / or other substrates such as polymer substrates (for example, polycarbonate substrates, cyclic olefin copolymer (COP) substrates, and / or similar) may be used.

[0038] In one embodiment, the optical filter 400 may have a low center wavelength shift with respect to the angle of incidence. The center wavelength of the passband shifts by less than 15 nm with respect to the angle of incidence from 0° to 60°. In some examples, the center wavelength of the passband may shift by less than 5 nm with respect to the angle of incidence from 0° to 40°.

[0039] As mentioned above, Figure 4 is provided merely as an example. Other examples may differ from those described in relation to Figure 4.

[0040] Figures 5A to 5D are diagrams of one or more examples of sputter deposition systems for one or more embodiments described herein.

[0041] As shown in Figure 5A, an example of a sputter 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 silicon material, a specific concentration of silicon-germanium material selected based on the optical properties of a particular concentration, and / or the like. In other examples, the angle of the cathode 530 may be configured so 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 can 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 sputter deposition system may sputter one or more layers onto the substrate 520 via DC sputtering.

[0042] As shown in Figure 5A, target 531 may be sputtered in the presence of hydrogen (H2) and an inert gas such as argon to deposit layers of silver material, silicon hydride (Si:H) material, silicon hydride-germanium (SiGe:H) material, silicon dioxide (SiO2) material, and / or similar materials onto substrate 520. For example, target 531 (and other targets as described herein) may deposit alternating layers of silver and silicon hydride on a first side of substrate 520 (for example, to form an ITF bandpass filter) and alternating layers of silicon dioxide and silicon hydride on a second side of substrate 520 (for example, to control the optical performance of an ITF bandpass filter as described herein).

[0043] An inert gas may be supplied into the chamber via the anode 550 and / or PAS 560. Hydrogen is introduced into the vacuum chamber 510 via the PAS 560 which activates the hydrogen. Alternatively, the cathode 530 may activate the hydrogen, in which case the hydrogen may be introduced from another part of the vacuum chamber 510, or the anode 550 may activate the hydrogen, in which case the anode 550 may introduce the hydrogen into the vacuum chamber 510. In some embodiments, the hydrogen may take the form of hydrogen gas, a mixture of hydrogen gas and a noble gas (e.g., argon gas), and / or similar. The PAS 560 may be positioned near the threshold of the cathode 530 so that the plasma from the PAS 560 and the plasma from the cathode 530 overlap. The use of the PAS 560 allows the 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 layers are deposited at deposition rates of approximately 0.05 nm / s to approximately 2.0 nm / s, approximately 0.5 nm / s to approximately 1.2 nm / s, approximately 0.8 nm / s, and / or similar rates.

[0044] In this specification, the sputtering procedure is described in a particular form and implementation, but other forms and implementations are possible. For example, hydrogen may be injected from other directions into the cathode 530 from a gas manifold near the threshold and / or similar.

[0045] 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 may be a silicon target, and the second target 591 may be a silver target. Thus, as described herein, the first target 581 can be a silicon target 581, and the second target 591 can be a silver target 591. However, it will be understood that the first target 581 and / or the second target 591 may be made from other suitable materials for forming the filter layer.

[0046] As shown in Figure 5B, the silicon target 581 is oriented at approximately 0 degrees relative to the substrate 520 (for example, nearly parallel to the substrate 520), and the silver target 591 is oriented at approximately 120 degrees relative to the substrate 520. In this case, silicon and silver are sputtered onto the substrate 520 from the silicon target 581 and the silver target 591, respectively, by cathodes 580 and 590. In this case, using two targets 581 and 591, the manufacture of an ITF bandpass filter such as the ITF bandpass filter 200 can be completed without requiring the release of the vacuum provided by the sputtering deposition system to change the target material, thereby reducing the manufacturing time.

[0047] As shown in Figure 5C, in a similar sputtering deposition system, the silicon target 581 and the silver target 591 are oriented at approximately 60 degrees relative to the substrate 520, and silicon and silver are sputtered onto the substrate 520 from the silicon target 581 and the silver target 591, respectively, by cathodes 580 and 590.

[0048] As shown in Figure 5D, in a similar sputtering deposition system, the silicon target 581 is oriented at approximately 120 degrees relative to the substrate 520, and the silver target 591 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 silicon target 581 and the silver target 591, respectively, by cathodes 580 and 590.

[0049] With respect to Figures 5A to 5D, each component in the silicon sputter deposition system may result in different relative concentrations of silicon, silicon and silver, and / or similar. Although this specification describes different configurations of components, different relative concentrations of silicon and germanium may also be achieved using different materials, different manufacturing processes, and / or similar.

[0050] As shown above, Figures 5A–5D are provided simply as one or more examples. Other examples may differ from those described with respect to Figures 5A–5D.

[0051] Figures 6A–6B illustrate one or more exemplary embodiments 600 described herein. As shown in Figure 6A, an 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 a sensor determination. The sensor system 610 includes an optical filter structure 620 including an optical filter 630, and an optical sensor 640. For example, the optical filter structure 620 may include an optical filter 630 that performs a passband filtering function or other type of optical filtering. The sensor system 610 includes an optical transmitter 650 that transmits an optical signal toward a target 660 (e.g., a person, an object, and / or the like).

[0052] While embodiments described herein relate to optical filters in sensor systems, embodiments may also be used outside and / or similarly in sensor systems.

[0053] As further shown by Figure 6A and reference no. 670, the input optical signal is directed to the optical filter structure 620. The input optical signal may include NIR light emitted by the optical transmitter 650 and ambient light from the environment in which the sensor system 610 is being used. For example, if the optical filter 630 is a bandpass filter, the optical transmitter 650 may direct near-infrared (NIR) light towards the user for a gesture recognition system (for example, a gesture performed by the target 660), and the NIR light is reflected from the target 600 (for example, the user) towards the optical sensor 640, enabling the optical sensor 640 to perform NIR light measurements. In this case, the ambient light may be directed to the optical sensor 640 from one or more ambient light sources (for example, a light bulb or the sun). In other examples, multiple light beams may be directed towards the target 660, and a subset of the multiple light beams may be reflected towards the optical filter structure 620, which may be positioned at an inclined angle to the optical sensor 640, as shown. In some embodiments, other tilt angles may be used (for example, a 0-degree tilt angle for a bandpass filter).

[0054] In some embodiments, the optical filter structure 620 may be positioned and / or formed directly on the optical sensor 640 rather than being positioned at a distance from the optical sensor 640. For example, the optical filter structure 620 may be coated and patterned on the optical sensor 640, for example, using photolithography. In other examples, the light transmitter 650 can direct NIR light toward other types of targets 660, such as detecting objects approaching a vehicle, detecting objects approaching a visually impaired person, detecting proximity to an object (e.g., using LIDAR technology), and / or similar, so that the NIR light and ambient light are directed toward the optical sensor 640.

[0055] As further shown in Figure 6A and reference numeral 680, a portion of the optical signal passes through the optical filter 630 and the optical filter structure 620. For example, the optical filter 630 may include any of the optical filter coating portions 410 of the optical filter 400 described above, and may reflect a portion of the light in a first direction. In this case, the optical filter 630 blocks the visible light of the input optical signal without excessively blocking the NIR light and without introducing an excessive angular shift as the incident angle of the input optical signal increases.

[0056] As further shown by Figure 6A and reference numeral 690, based on a portion of the optical signal passed to the optical sensor 640, the optical sensor 640 can provide an output electrical signal to the sensor system 610 for use, for example, in recognizing user gestures or detecting the presence of an object. In some embodiments, other arrangements of the optical filter 630 and the optical sensor 640 may be used. For example, the optical filter 630 may direct the second portion of the optical signal in a different direction to an optical sensor 640 located at a different position, rather than passing the second portion of the optical signal in the same straight line as the input optical signal. In other examples, the optical sensor 640 may be an avalanche photodiode, an indium-gallium-arsenide (InGaAs) detector, an infrared detector, and / or similar.

[0057] 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 transmitter 650, and a target. Figure 6B shows a particular exemplary embodiment 600 including an optical filter 630, as described herein.

[0058] The optical transmitter 650 emits light at an emission wavelength in the wavelength range of 800 nm to 1100 nm. The optical transmitter 650 emits modulated light (for example, a light pulse). The optical transmitter 650 may be a light-emitting diode (LED), an LED array, a laser diode, or a laser diode array. The optical transmitter 650 emits light toward a target 660 that reflects the light back toward the sensor system 610. If the sensor system 610 is a gesture recognition system, the target 660 is the user of the gesture recognition system. The sensor system 610 may be a proximity sensor system, a three-dimensional (3D) imaging system, a distance sensing system, a depth sensor, and / or other suitable sensor system.

[0059] The optical filter 630 is positioned to receive the emitted light after reflection by the target 660. The optical filter 630 has a passband that includes the emitted wavelength and at least partially overlaps with the wavelength range of 800 nm to 1100 nm. The optical filter 630 is a bandpass filter, such as an ITF bandpass filter. The optical filter 630 transmits the emitted light from the optical transmitter 650 while substantially blocking ambient light.

[0060] The optical sensor 640 is positioned to receive light emitted after transmission by the optical filter 630. In some embodiments, the optical filter 630 is formed directly on the optical sensor 640. For example, the optical filter 630 may be coated and patterned on the sensor (e.g., a proximity sensor) in wafer-level processing (WLP) (e.g., by photolithography).

[0061] If the sensor system 610 is a proximity sensor system, the optical sensor 640 is a proximity sensor that detects light emission to sense the proximity of the target 660. If the sensor system 610 is a 3D imaging system or a gesture recognition system, the optical sensor 40 is a 3D imaging sensor (e.g., a charge-coupled device (CCD) chip or a complementary metal-oxide-semiconductor (CMOS) chip) that detects light emission and provides a 3D image of, for example, the user, the target 660. The 3D imaging sensor is converted into electrical signals for processing by a processing system (e.g., an application-specific integrated circuit (ASIC) chip or a digital signal processing (DSP) chip). If the sensor system 610 is a gesture recognition system, the processing system processes the user's 3D image to recognize the user's gestures. Other types of sensor systems 610 may be possible.

[0062] As previously stated, Figures 6A–6B are provided simply as one or more examples. Other examples may differ from those described with respect to Figures 6A–6B.

[0063] Figure 7 is a flowchart of an exemplary process 700 related to the manufacture of an ITF bandpass filter having silicon hydride and silver. In some embodiments, one or more process blocks in Figure 7 may be performed by a manufacturing device (for example, the sputter deposition system in Figures 5A-5D).

[0064] As shown in Figure 7, process 700 deposits a first subset of the optical filter layer of an optical filter, the first subset of the optical filter layer comprising a first material having a first refractive index, the first material comprising at least silicon and hydrogen (block 710). For example, a manufacturing device deposits a first subset of the optical filter layer of an optical filter, the first subset of the optical filter layer comprising a first material having a first refractive index, and as mentioned above, the first material may comprise at least silicon and hydrogen.

[0065] As further shown in Figure 7, the process 700 includes depositing a second subset of the optical filter layer of the optical filter, the second subset of the optical filter comprising a second material having a second refractive index, the second material being different from the first material, the second refractive index being less than the first refractive index, and the second material may contain at least silver (block 720). For example, the manufacturing apparatus deposits a second subset of the optical filter layer of the optical filter, the second subset of the optical filter layer comprising a second material having a second refractive index, the second material being different from the first material, and the second material may contain at least silver as described above.

[0066] Process 700 may include any single implementation described below, or several embodiments such as any combination of implementations, and / or association with one or more other processes described herein.

[0067] In the first embodiment, the deposition of a first subset of the optical filter layer includes sputtering of the first subset of the optical filter layer using a first target.

[0068] In the second embodiment, either alone or in combination with the first embodiment, the deposition of a second subset of the optical filter layer includes sputtering of the second subset of the optical filter layer using a second target.

[0069] In the third embodiment, either alone or in combination with one or more of the first and second embodiments, the process 700 includes the deposition of a third subset of the optical filter layer of an optical filter, the third subset of the optical filter layer including a third material having a third refractive index.

[0070] In the fourth embodiment, either alone or in combination with one or more of the first to third embodiments, the first material is silicon hydride (SiH), the second material is silver (Ag), and the third material is silicon dioxide (SiO2).

[0071] In the fifth embodiment, either alone or in combination with one or more of the first to fourth embodiments, a third subset of the optical filter layer is deposited using at least one of the first target used for depositing the first subset of the optical filter layer, or a second target used for depositing the second subset of the optical filter layer.

[0072] In the sixth embodiment, the optical filter is manufactured using a single vacuum chamber, either alone or in combination with one or more of the first to fifth embodiments.

[0073] Figure 7 shows an exemplary block of process 700, but in some embodiments, process 700 may include additional blocks, fewer blocks, different blocks, or blocks in different arrangements than those shown in Figure 7. Furthermore, or instead, two or more blocks of process 700 may be performed in parallel.

[0074] The foregoing disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit practices to the nature of those disclosed. Modifications and variations may be made in light of the foregoing disclosure or derived from the practice of the embodiments.

[0075] As used herein, satisfying a threshold can refer to a value greater than the threshold, greater than or equal to the threshold, less than or equal to the threshold, less than or equal to the threshold, or equal to the threshold, depending on the context.

[0076] Even if specific combinations of features are described in the claims 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 claims and / or disclosed in the specification. Each of the dependent claims listed below may directly depend on only one claim, however the disclosure of various embodiments may include each dependent claim combined with all other claims in the set of claims.

[0077] No element, action, or instruction used herein shall be construed as important or essential unless expressly stated otherwise. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items and may be interchangeable with “one or more.” Additionally, as used herein, the article “the” is intended to include one or more items referred to in relation to the article “the” and may be interchangeable with “one or more.” Furthermore, as used herein, the term “pair” is intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items) and may be interchangeable with “one or more.” If only one item is intended, the phrase “only one” or similar language shall be used. Furthermore, as used herein, terms such as “has,” “have,” and “having” are intended to be unrestricted terms. Furthermore, the phrase “based on” is intended to mean “at least partially based” unless otherwise specified. Furthermore, as used herein, the term "or" is intended to be inclusive when used in conjunction with "and / or" unless otherwise specified (for example, when used in combination with "either" or "only one of").

Claims

1. A first subset of an optical filter layer comprising a first material having a first refractive index, wherein the first material comprises at least silicon and hydrogen, amorphous silicon (a-Si), or silicon-germanium (SiGe), A second subset of an optical filter layer comprising a second material having a second refractive index, wherein the second material differs from the first material and the second material contains at least silver, A third subset of an optical filter layer comprising a third material having a third refractive index, wherein the third material differs from the first and second materials, and the third material comprises at least silicon dioxide, An inductive transmitting filter comprising a set of optical filter layers composed of three materials, each comprising alternating layers of the first subset and the second subset, and alternating layers of the first subset and the third subset.

2. The inductive transmitting filter according to claim 1, wherein the first material is at least one of a silicon hydride (Si:H) material or an amorphous silicon (a-Si) material.

3. The inductive transmitting filter according to claim 1, wherein the first material is at least one of a silicon-germanium (SiGe) material or a silicon hydride-germanium (SiGe:H) material.

4. The inductive transmitting filter according to claim 1, further comprising a substrate, wherein the set of optical filter layers is disposed on the substrate.

5. The inductive transmitting filter according to claim 4, wherein the set of optical filter layers is disposed on a first side of the substrate, and further comprises a coating disposed on a second side of the substrate.

6. The inductive transmission filter according to claim 1, wherein the first refractive index is greater than 3.3 in the spectral range from 800 nanometers (nm) to 1700 nm.

7. Depositing a first subset of the optical filter layer of an optical filter, A first subset of the optical filter layer comprises a first material having a first refractive index, wherein the first material comprises at least silicon and hydrogen, amorphous silicon (a-Si), or silicon-germanium (SiGe). Depositing a second subset of the optical filter layer of the aforementioned optical filter, A second subset of the optical filter layer comprises a second material having a second refractive index, wherein the second material differs from the first material, and the second material contains at least silver, and Depositing a third subset of the optical filter layer of the aforementioned optical filter, A third subset of the optical filter layer comprises a third material having a third refractive index, wherein the third material differs from the first and second materials, and the third material comprises at least silicon dioxide. A method for manufacturing an optical filter composed of three materials, comprising forming alternating layers of the first subset and the second subset, and forming alternating layers of the first subset and the third subset.

8. The method according to claim 7, wherein depositing a first subset of the optical filter layer includes sputtering the first subset of the optical filter layer using a first target.

9. The method according to claim 7, wherein depositing a second subset of the optical filter layer includes sputtering the second subset of the optical filter layer using a second target.

10. The method according to claim 7, wherein the first material is silicon hydride (Si:H), the second material is silver (Ag), and the third material is silicon dioxide (SiO2).

11. The method according to claim 7, wherein the third subset of the optical filter layer is deposited using at least one of a first target used to deposit the first subset of the optical filter layer, or a second target used to deposit the second subset of the optical filter layer.

12. The method according to claim 7, wherein the optical filter is manufactured using a single vacuum chamber.

13. Includes an optical filter that filters the input optical signal and provides a filtered input optical signal, The optical filter includes a set of optical filter layers, The set of optical filter layers, A first subset of optical filter layers comprising a first material having a first refractive index, wherein the first material comprises at least silicon and hydrogen, amorphous silicon (a-Si), or silicon-germanium (SiGe), A second subset of optical filter layers comprising a second material having a second refractive index, wherein the second material differs from the first material and the second material contains at least silver, A third subset of optical filter layers comprising a third material having a third refractive index, wherein the third material differs from the first and second materials, and the third material comprises at least silicon dioxide, The first subset and the second subset are arranged in alternating layers, and the first subset and the third subset are arranged in alternating layers, An optical receiver composed of three materials receives the filtered input optical signal and provides an output electrical signal, Optical systems, including

14. The optical system according to claim 13, further comprising an optical transmitter for transmitting an output optical signal, wherein the input optical signal comprises at least the output optical signal and an ambient light signal.

15. The optical system according to claim 13, wherein the optical filter is associated with a transmission rate greater than 50% at 950 nanometers.

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