Angle selective filter

Abstract

In some implementations, an optical filter assembly includes: a first optical filter disposed on a first side of a substrate, where the first optical filter is a bandpass filter; and a second optical filter disposed on a second side of the substrate, wherein the second optical filter is associated with a threshold angular offset at a threshold angle of incidence.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 510,458, entitled “WAVELENGTH AND ANGLESENSITIVE BANDPASS FILTER,” filed on June 27, 2023. The disclosure of the prior application is considered a part of and incorporated by reference into this patent application. Background Art

[0003] Optical filters are used to select spectral bands or spectral components of incident light. For example, a high-pass filter selects light with wavelengths longer than the edge wavelength of the filter. Conversely, a low-pass filter selects light with wavelengths shorter than the edge wavelength. A bandpass filter is a different type of filter that selects light with wavelengths close to the center wavelength of the filter within the bandwidth of the filter. A tunable bandpass filter is an optical filter whose center wavelength can be adjusted or tuned.

[0004] When the angle of incidence (AOI) of light directed to the optical filter changes from a configured incidence (e.g., 0 degrees, 45 degrees, 90 degrees, etc.) to a threshold angle of incidence (e.g., a deviation from the configured incidence of greater than about 30 degrees), the filter performance of the optical filter may be degraded. In this case, the band edge may experience a blue shift to shorter wavelengths. In addition, when the angle of incidence changes from a configured incidence (e.g., orthogonal incidence, non-orthogonal selective incidence, etc.) to a threshold angle of incidence (e.g., an effect greater than a threshold level), polarization effects become significant for the optical filter. Summary of the invention

[0005] In some implementations, an optical filter assembly includes: a first optical filter disposed on a first side of a substrate, wherein the first optical filter is a bandpass filter; and a second optical filter disposed on a second side of the substrate, wherein the second optical filter is associated with a threshold angular offset at a threshold incident angle.

[0006] In some implementations, an optical filter includes: a bandpass filter having a transmittance of at least a first threshold level at a configured center wavelength, wherein a first side of the bandpass filter is configured to receive a light beam; and an angle-shift filter having an angular shift of at least a second threshold level at a configured center wavelength at an incident angle greater than a configured value, wherein the angle-shift filter is disposed on a second side of the bandpass filter.

[0007] In some implementations, an optical system includes an electro-optical component; a bandpass filter having a transmittance of at least a first threshold level at a configured center wavelength, wherein a first side of the bandpass filter is configured to receive a light beam; and an angular shift filter having an angular shift of at least a second threshold level at the configured center wavelength at an incident angle greater than a configured value, wherein the angular shift filter is disposed on a second side of the bandpass filter, and wherein the bandpass filter and the angular shift filter are aligned with the electro-optical component. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of an example implementation described in this article;

[0009] Figure 2A and Figure 2B is a schematic diagram of an example optical filter assembly; and

[0010] Figure 3A-3H is a schematic diagram of the optical characteristics of an example optical filter. DETAILED DESCRIPTION

[0011] The following detailed description of example implementations refers to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements. The following description takes a spectrometer as an example. However, the techniques, principles, processes, and methods described herein can be used with any sensor, including but not limited to other optical sensors and spectral sensors.

[0012] An optical sensor device may include an array of sensor elements for receiving light emitted from a light source (such as an optical emitter, a light bulb, an ambient light source, etc.). For example, in a spectrometer, the optical sensor device may include an array of sensor elements for receiving light reflected from a target object, thereby enabling identification of the target object. The sensor element may be associated with an optical filter that filters the light to the sensor element so that the sensor element can acquire information about electromagnetic frequencies in a specific spectral range. For example, the sensor element may be aligned with an optical filter having a passband in a near infrared (NIR) spectral range, a visible spectral range, an ultraviolet spectral range, etc.

[0013] The total integrated flux of the bandpass filter can be relatively insensitive to angular offsets (e.g., changes in the configured angle of incidence (AOI) of light directed to the optical filter). For example, the bandpass filter can allow a relatively large proportion of light to pass through the filter even at relatively large angles of incidence (e.g., greater than a threshold value of, for example, 30 degrees from the configured angle of incidence). However, light passing through the bandpass filter at relatively large angles of incidence can include stray light, which increases the noise level detected by a sensor element such as a photodiode. In addition, when multiple light sources are present, allowing light with relatively large angles of incidence to pass through the bandpass filter can result in crosstalk between the multiple light sources. In other words, stray light from an unintended source (e.g., the sun or a light bulb in a room) can pass through the bandpass filter, and light from an intended source (e.g., an optical emitter) but intended to be directed to a different sensor element can also pass through the bandpass filter. In addition, when multiple devices or channels use the same light source wavelength as the wavelength of interest for a particular detector, the presence of multiple devices or channels may result in stray light being directed to a particular detector at a particular angle of incidence (e.g., an angle greater than a threshold). Therefore, it is desirable to limit the light passing through the bandpass filter to within a configured angular range to avoid excessive noise and / or crosstalk between light sources.

[0014] Some implementations described herein provide an optical filter assembly, an optical device, an optical element, an optical module, an optical system, etc., wherein two optical filters are arranged on a common substrate surface position to limit the incident angle of light and provide bandpass interference filtering. For example, a composite optical filter may include a first optical filter as a bandpass optical filter, and a second optical filter as a high angle offset (e.g., greater than or equal to a threshold angle offset) optical filter. The first optical filter and the second optical filter may be implemented on opposite sides of the substrate or on a single side of the substrate (e.g., by using two different optical filters, or a single optical filter combining the functions of the first optical filter and the second optical filter). In this way, the optical filter assembly can transmit light at a configured incident angle, and reflect or block light greater than a threshold incident angle, and reflect or block light outside the configured passband. In this way, the influence of an incident angle greater than a threshold can be avoided for the bandpass filter, such as by avoiding excessive noise or crosstalk in an optical sensor or sensor element array.

[0015] Figure 1 is a schematic diagram of an example implementation 100 described herein. Figure 1As shown, example implementation 100 includes optical system 110. Optical system 110 can be part of an optical system and can provide an electrical output corresponding to a sensor determination. For example, optical system 110 can be part of a LIDAR system, a three-dimensional sensing system, a spectroscopy system, a gesture recognition system, a facial recognition system, an object recognition system, an imaging system, an iris recognition system, a motion tracking system, or a communication system, etc.

[0016] In some implementations, the optical system 110 may include an optical filter assembly 120, which may include a substrate 130 and a set of optical filters 140. In some implementations, the optical filter assembly 120 may include a bandpass filter. For example, the optical filter assembly 120 may include one or more layers forming a bandpass interference filter, which is configured to pass a first portion of light in a first wavelength range and block a second portion of light in a second wavelength range, as described in more detail herein. Additionally or alternatively, the optical filter assembly 120 may include a long wavelength passband (LWP) filter, a short wavelength passband (SWP) filter, a low angle shift (LAS) bandpass filter, a hyper-low angle shift (HLAS) bandpass filter, a wide wavelength passband (BWP) filter, an infrared cutoff (IR Cut) filter, a notch filter, etc. In some implementations, the optical filter assembly 120 can have a bandpass between 200 nanometers (nm) and 14,000 nm and can be used in the visible spectral range, the NIR spectral range, the mid-wave infrared (MWIR) spectral range, the long-wave infrared (LWIR) spectral range, the ultraviolet spectral range, etc.

[0017] In some implementations, the optical filter assembly 120 may include an angle-shifting filter. For example, the optical filter assembly 120 may include one or more layers forming an angle-sensitive filter that is configured to pass a first portion of light at a first range of incident angles (e.g., without shifting the wavelength of the first portion of light) and shift the wavelength of a second portion of light at a second range of incident angles. In this case, by shifting the wavelength of the second portion of light, the optical filter assembly 120 may ensure that stray light entering the cavity of the optical system 110 is not at a wavelength of interest for the optical system 110. In other words, when the optical system 110 is configured to measure characteristics of light at, for example, a wavelength of 980 nm, the angle-sensitive filter ensures that light having an orthogonal incident angle (e.g., 0 degree incident angle, ±10 degrees) is not shifted, but light having a threshold incident angle (e.g., greater than 10 degrees or less than -10 degrees) is shifted to a different wavelength (e.g., to a center wavelength of 900 nm or 1100 nm). Thus, by shifting the wavelength of the second portion of light, the first portion of light may be measured without (or with a reduced amount of) noise or crosstalk from the second portion of light.

[0018] In some implementations, the optical filter assembly 120 may include one or more other filters. For example, the optical filter assembly 120 may include an anti-reflection filter. For example, the optical filter assembly 120 may include an anti-reflection filter that is configured for the same bandpass region as the bandpass filter of the optical filter assembly 120. In this case, the anti-reflection filter may be coated on a surface or included within the bandpass filter.

[0019] Although some implementations described herein may be described in terms of one or more optical filters in a sensor system, some (other) implementations may be for another type of system, optical elements external to the sensor system, optical elements of an optical package, etc. In some implementations, the optical system 110 may include a photodetector system, an avalanche photodetector system, a single photon avalanche diode (SPAD) detector system, or a complementary metal oxide semiconductor (CMOS) detector system.

[0020] In some implementations, the substrate 130 may be a transparent substrate, such as a glass substrate, a silicon substrate, a germanium substrate, etc. In some implementations, the substrate 130 may be a silicon dioxide substrate. In some implementations, the substrate 130 may be disposed on a specific side of the set of optical filters 140. For example, the substrate 130 may have a first optical filter 140 (e.g., an angle sensitive filter) disposed on a surface of the substrate 130, and the second optical filter 140 may be disposed on top of the first optical filter 140 (e.g., such that the first optical filter 140 is sandwiched by the second optical filter 140 and the substrate 130). In other words, both the first optical filter 140 and the second optical filter 140 (in any order) may be disposed on the same side of the substrate 130 (or the optical filter 140 may form a substrate for another optical filter 140). Additionally or alternatively, the substrate 130 may have the optical filter 140 on the opposite side of the substrate 130. For example, the first optical filter 140 can be disposed on a first side of the substrate 130, and the second optical filter 140 can be disposed on a second side of the substrate 130 (e.g., such that the first optical filter 140 and the second optical filter 140 sandwich the substrate 130). In some implementations, the substrate 130 can be omitted. For example, a bandpass filter (in the set of optical filters 140) can be directly disposed on the surface of the angle-sensitive filter (in the set of optical filters 140), without a substrate in between or without a substrate on which the filter is disposed. In this case, the bandpass filter and the angle-sensitive filter are matched to have coherence of light between the bandpass filter and the angle-sensitive filter. In some implementations, another medium can separate the filters in the set of optical filters 140, such as an air gap, a gas gap, or a liquid gap, etc., instead of a substrate separating the filters in the set of optical filters 140.

[0021] In some implementations, the set of optical filters 140 may include a set of alternating high refractive index layers and low refractive index layers (e.g., an alternating arrangement of multiple high refractive index layers and multiple low refractive index layers). For example, the set of optical filters 140 may include a high refractive index material, such as amorphous silicon or niobium titanium oxide, etc. Additionally or alternatively, the set of optical filters 140 may include a silicon layer, a silicon dioxide layer, a hydrogenated silicon layer, a tantalum pentoxide layer, a niobium pentoxide layer, a germanium layer, a silicon germanium layer, a hydrogenated silicon germanium layer, a tantalum niobium oxide layer, a titanium dioxide layer, a silicon nitride layer, or an aluminum nitride layer, etc. Additionally or alternatively, the set of optical filters 140 may include another type of high refractive index material layer having a refractive index greater than 2.0, greater than 2.5, greater than 3.0, greater than 3.5, etc.

[0022] In some implementations, the group of optical filters 140 may include a low refractive index material, such as silicon dioxide. Additionally or alternatively, the group of optical filters 140 may include another type of low refractive index material layer having a refractive index less than 2.5, less than 2.0, less than 1.5, etc. For example, the group of optical filters 140 may include a set of alternating layers of amorphous silicon layers and silicon dioxide layers for a bandpass filter operating at 940nm, and a set of alternating layers of tantalum oxide layers and silicon oxide layers for an angle sensitive filter. In some implementations, the group of optical filters 140 may include three or more different materials. For example, the group of optical filters 140 may have a subset of hydrogenated silicon layers, a subset of tantalum pentoxide layers, and a subset of silicon dioxide layers. In this case, the use of three or more different types of layers may enable the optical filter 140 to achieve higher transmittance and / or reduced angular shift at certain wavelengths compared to using only two different materials.

[0023] like Figure 1 As further shown, as shown at reference numeral 170, the input optical signal is directed at the optical filter assembly 120 at one or more incident angles θ. For example, the input optical signals 150-1 and 150-2 can be directed at the optical filter assembly 120 at incident angles θ0 (e.g., configured incident angles) and θ. As shown at reference numeral 175, a first portion of the input optical signal is reflected by the optical filter assembly 120. For example, based on a portion of the input optical signal being outside of a passband of a bandpass filter in the set of optical filters 140, the set of optical filters 140 can reflect the portion of the input optical signal.

[0024] like Figure 1 As further shown in the figure numeral 180, another portion of the optical signal is transmitted through the optical filter assembly 120. For example, a portion of the input optical signal that is within the passband of the optical filter assembly 120 passes through the optical filter assembly 110, as described in more detail herein. Some of the portions of the input optical signal that are within the passband of the optical filter assembly 120 may be angularly offset and / or blocked. For example, light passing through the optical filter assembly 120 at an incident angle θ0 is offset and / or passed by the angle-sensitive filters in the set of optical filters 140. In contrast, light at an incident angle θ or greater is angularly offset and / or blocked by the angle-sensitive filters in the set of optical filters 140. Therefore, the portion of the input optical signal that passes through the optical filter assembly 120 includes a first sub-portion that is not offset or blocked and a second sub-portion that is offset or blocked.

[0025] Although the terms "unshifted" or "unblocked" and "shifted" or "blocked" are used, all filter spectra can be shifted or blocked by a certain amount (e.g., a configured percentage), and "unshifted" or "unblocked" light can include light in which the filter spectrum is shifted less than or equal to a threshold amount or has a transmission percentage greater than or equal to a threshold, and "shifted" can include light in which the filter spectrum is shifted greater than a threshold amount or is transmitted less than a threshold percentage.

[0026] As shown in reference numeral 185, based on a portion of the input light signal being passed to the optical sensor 160 (e.g., an optical detector or a photodetector), the optical sensor 160 can provide an output electrical signal to the optical system 110. For example, the optical sensor 160 can provide an output electrical signal identifying the intensity of the light, the characteristics of the light (e.g., spectral characteristics), the wavelength of the light, etc. In some implementations, the optical sensor 160 can perform measurements of only a sub-portion of the light. For example, the optical sensor 160 can perform measurements on light that passes through a filter at a low angle, but can not perform measurements on light that is reflected or blocked at the filter at a high angle. Additionally or alternatively, the optical sensor 160 can perform measurements of the light, but the optical sensor 160 can be configured so that the amount of noise or crosstalk in the measurement caused by the offset light is less than a threshold noise or crosstalk amount.

[0027] As mentioned above, Figure 1 Provided as an example only. Other examples may be Figure 1 Different from what is described in .

[0028] Figure 2A and Figure 2B is a schematic diagram of an example optical filter assembly 200 / 200'. Figure 2A As shown, the optical filter assembly 200 includes a substrate 210 on which a first optical filter 220 is disposed on a first side and a second optical filter 230 is disposed on a second side.

[0029] In some implementations, the first optical filter 220 may be a bandpass filter exhibiting a low angular offset. For example, the first optical filter 220 may be a low angular offset bandpass filter manufactured using a silver (Ag) material. In some implementations, the silver material may form a photosensitive coating, a red, green, and blue color filter, or another type of low angular offset filter. Additionally or alternatively, the first optical filter 220 may be a low angular offset bandpass filter manufactured using hydrogenated silicon (Si:H). In some implementations, the first optical filter 220 may be associated with an angular offset less than a threshold when the incident angle is greater than a threshold, as described in more detail herein. For example, within a specific range of incident angles, the first optical filter 220 may be associated with an angular offset less than 20%, an angular offset less than 10%, an angular offset less than 5%, and / or an angular offset less than 1%, etc. In this case, the specific range of incident angles may be a range of about 0 degrees to about 60 degrees, about 0 degrees to about 45 degrees, about 0 degrees to about 30 degrees, etc.

[0030] In some implementations, a low angle offset (LAS) filter (such as a first optical filter) may include a bandpass filter that exhibits, for example, a passband center angle offset of less than about 20nm in an angle range of about 0 degrees to about 30 degrees in, for example, a near infrared (NIR) spectral range. In some implementations, in the NIR spectral range, the LAS filter may include amorphous silicon or hydrogenated silicon as a high refractive index material. In some implementations, an ultra-low angle offset (HLAS) filter may include a bandpass filter that exhibits, for example, a passband center angle offset of less than about 10nm in an angle range of about 0 degrees to about 30 degrees in, for example, a NIR spectral range. In some implementations, in the NIR spectral range, the HLAS filter may include amorphous silicon or hydrogenated silicon as a high refractive index material. Although the LAS and HLAS types of the first optical filter are described with respect to the NIR spectral range, it should be understood that the LAS filter and the HLAS filter may be used for the first optical filter for other spectral ranges. In some implementations, the first optical filter 220 may include multiple layers. For example, multiple layers may be deposited and / or patterned, such as by using a photolithography process, to form the first optical filter 220. In some implementations, the optical filter assembly 200 may be associated with a specific size. For example, the optical filter may be associated with a thickness between approximately 10 nm and 5000 nm.

[0031] In some implementations, the second optical filter 230 may be an angle-sensitive filter that exhibits a high amount of angular offset. For example, the second optical filter 230 may be associated with an angular offset greater than 1%, greater than 5%, greater than 10%, greater than 20%, greater than 30%, etc. at a specific range of incident angles. In some implementations, an angle-sensitive filter or a high-angle offset filter such as the second optical filter 230 may include a filter associated with an angular offset in the range of 10% to 20%. In some implementations, the specific range of incident angles in which the configured angular offset occurs may be between about 0 degrees to about 90 degrees, about 10 degrees to about 60 degrees, about 30 degrees to about 45 degrees, etc. In some implementations, the specific range of incident angles may be greater than about 30 degrees, greater than about 45 degrees, etc. In some implementations, the second optical filter 230 may be made of a material having a refractive index less than a threshold value. For example, the second optical filter 230 may be a filter based on silicon dioxide (SiO2), a filter based on tantalum pentoxide (Ta2O5), etc. In some implementations, the second optical filter 230 may include multiple layers. For example, multiple layers may be deposited and / or patterned, such as by using a photolithography process or the like, to form the second optical filter 230 .

[0032] In some implementations, at angles less than a threshold angle of incidence (or less than a threshold deviation from a configured angle of incidence), greater than a threshold percentage of light may pass through the first optical filter 220 and the second optical filter 230. For example, for light having an angle of incidence less than about 60 degrees, less than about 45 degrees, less than about 30 degrees, etc., the first optical filter 220 and the second optical filter 230 may allow a transmittance greater than about 75%, a transmittance greater than about 90%, a transmittance less than about 95%, a transmittance greater than about 99%, a transmittance greater than about 99.9%, etc.

[0033] Conversely, for light associated with a threshold angle of incidence greater than or equal to a threshold (e.g., light rays 240-5 and 240-6, which deviate from the configured angle of incidence by a threshold amount), the light may be blocked from passing through the first optical filter 220 and / or the second optical filter 230. In this case, the light may be reflected by the first optical filter 220 and / or the second optical filter 230. In some implementations, less than or equal to a threshold percentage of light may be blocked by the first optical filter 220 and the second optical filter 230 at a threshold angle of incidence greater than or equal to a threshold. For example, for light having an angle of incidence greater than or equal to approximately 30 degrees, greater than or equal to approximately 45 degrees, greater than or equal to approximately 60 degrees, etc., the first optical filter 220 and / or the second optical filter 230 may be associated with a transmittance less than or equal to approximately 50%, a transmittance less than or equal to approximately 25%, a transmittance less than or equal to approximately 10%, a transmittance less than or equal to approximately 5%, a transmittance less than or equal to approximately 1%, etc. In this case, the optical filter assembly 200 can block a threshold percentage of light, such as about 75%, about 90%, about 95%, about 99%, about 99.9%, about 99.99%, about 99.999%, etc. In this way, using a composite optical filter including a high angle offset component optical filter and a low angle offset component optical filter can eliminate the need for an aperture, thereby reducing the manufacturing complexity of the optical device, reducing its cost, reducing its packaging size, etc.

[0034] In some implementations, the optical filter assembly 200 can be associated with a specific spectral range for which the optical filter assembly 200 is transmissive within a first incident angle range that satisfies an incident angle threshold, and is not transmissive within a second incident angle range that does not satisfy the incident angle threshold. For example, the optical filter assembly 200 can be associated with a spectral range between about 600 nanometers (nm) to about 1200nm, about 700nm to about 1100nm, about 800nm ​​to about 1000nm, etc. Additionally or alternatively, the optical filter assembly 200 can be associated with a spectral range between about 1200nm to about 2000nm, about 1400nm to about 1800nm, about 1500nm to about 1700nm, etc. Additionally or alternatively, the optical filter assembly 200 can be associated with a spectral range between about 200nm to about 4000nm, about 1000nm to about 3000nm, about 1500nm to about 2500nm, etc. In some implementations, the optical filter assembly 200 can be associated with a spectral range between about 100 nm and about 14,000 nm, or a sub-range thereof. Additionally or alternatively, the optical filter assembly 200 can be associated with a visible spectral range, a near infrared spectral range, an ultraviolet spectral range, a combination thereof, or the like.

[0035] In some implementations, the optical filter assembly 200 may include one or more other filters, such as wave stops, edge filters, bandpass filters, etc. In some implementations, the optical filter assembly 200 may include a protective covering (e.g., to protect the first optical filter 220 and / or the second optical filter 230 from environmental degradation). In some implementations, the optical filter assembly 200 may include one or more layers of other materials. For example, such as for the first optical filter 220 or the second optical filter 230, the optical filter assembly 200 may include silicon (Si)-based materials, hydrogenated silicon (Si:H)-based materials, germanium (Ge)-based materials, hydrogenated germanium (Ge:H)-based materials, silicon germanium (SiGe)-based materials, aluminum (Al)-based materials, silver (Ag)-based materials, silicon dioxide (SiO2) materials, aluminum oxide (Al2O3) materials, titanium dioxide (TiO2) materials, niobium pentoxide (Nb2O5) materials, tantalum pentoxide (Ta2O5) materials, magnesium fluoride (MgF2) materials, niobium titanium oxide (NbTiOx) materials, niobium tantalum pentoxide materials (NbTa2O5), zinc oxide materials (ZnO), platinum (Pt) materials, gold (Au) materials, fluorescent materials, etc. In some implementations, a spacer layer or material may be included in one or more optical filters.

[0036] like Figure 2B As shown, the optical filter assembly 200' can allow light greater than or equal to a threshold incident angle to pass through, and can block light less than a threshold incident angle from passing through or angularly offset it. For example, the optical filter assembly 200' may include a first optical filter 220' and a second optical filter 230' deposited on a substrate 210'. The first optical filter 220' may be a low angle offset filter, and the second optical filter 230' may be a high angle offset filter. In this case, the first optical filter 220' and the second optical filter 230' may be configured so that the wavelength of light directed to the optical filter assembly 200' at a high incident angle (e.g., greater than or equal to a threshold incident angle) is transmitted to the optical filter assembly 200', and is reflected at a low incident angle (e.g., less than a threshold incident angle).

[0037] In some implementations, the optical filter assembly 200 / 200' can be bidirectional. For example, although the optical filter assembly 200 / 200' is shown as having light transmission in a particular direction, the optical filter assembly 200 / 200' can be configured to allow light to pass in another direction.

[0038] As mentioned above, Figure 2A and Figure 2B Provided as an example only. Other examples are possible and may be related to Figure 2A and Figure 2B Different than described.

[0039] Figure 3A-3H is a schematic diagram of the optical characteristics of an example optical filter.

[0040] like Figure 3A As shown, schematic diagram 300 shows the optical characteristics of a first optical filter 350, which can be a low angle offset filter having a passband at 940nm. As shown in schematic diagram 300, the first optical filter 350 is subjected to collimated light, which is unpolarized and directed to the first optical filter at an angle of incidence (AOI) in the range of 0° to 50°. In this case, at an AOI of 0°, the first optical filter 350 exhibits a transmittance of approximately 95% in a wavelength range from approximately 930nm to approximately 960nm (e.g., centered at approximately 940nm). At an AOI of 30°, the first optical filter 350 exhibits a transmittance of approximately 93% in a wavelength range from approximately 925nm to approximately 950nm. At an AOI of 50°, the first optical filter exhibits a transmittance of approximately 90% in a wavelength range from approximately 915nm to approximately 935nm.

[0041] like Figure 3B As shown, schematic diagram 302 shows the optical characteristics of the second optical filter 352, which can be a composite optical filter including a bandpass filter having a passband at 940nm and an angle-shifted filter. As shown in schematic diagram 302, the second optical filter 352 is subjected to collimated light, which is non-polarized and directed to the second optical filter 352 at an AOI in the range of 0° to 50°. In this case, at an AOI of 0°, the second optical filter 352 has a transmittance of approximately 95% in a wavelength range from approximately 930nm to approximately 955nm (e.g., centered at 940nm). At an AOI of 30°, the second optical filter 352 does not exceed a transmittance of 50% at any wavelength (and has a transmittance greater than approximately 10% in a wavelength range from approximately 910nm to approximately 945nm). At an AOI of 50°, the second optical filter 352 has no more than 15% transmittance at any wavelength (and has a peak transmittance of about 13% in the wavelength range of about 898 nm to about 900 nm). Thus, the second optical filter 352 has approximately the same passband as the optical filter 350 at low AOIs (e.g., AOI of 0°), but blocks most of the light at larger AOIs, rather than merely shifting the passband as occurs with the first optical filter 350.

[0042] like Figure 3CAs shown, schematic diagram 304 shows the optical characteristics of a first side of the second optical filter 352 (eg, a first component optical filter, such as a bandpass filter). Figure 3D As shown, schematic diagram 306 shows the optical characteristics of the second side (e.g., a second component optical filter, such as an angle-shifted filter, a high angle-shifted filter, or an angle-sensitive filter) of the second optical filter 352. As shown in schematic diagrams 304 and 306, the second side of the second optical filter 352 provides an angular sensitivity greater than the angular sensitivity provided by the first side of the optical filter 352.

[0043] like Figure 3E As shown, schematic diagram 308 shows the optical characteristics of the third optical filter 354, which can be another composite optical filter including a bandpass filter having a passband at 940nm and an angle-shifted filter. As shown in schematic diagram 308, the third optical filter 354 is subjected to collimated light, which is non-polarized and directed to the third optical filter 354 at an AOI in the range of 0° to 50°. In this case, at an AOI of 0°, the third optical filter 354 has a transmittance of about 90% in a wavelength range from about 930nm to about 955nm (e.g., centered at 940nm). At an AOI of 30°, the third optical filter 354 has a transmittance range of about 60%-70% in a wavelength range from about 910nm to about 950nm. At an AOI of 50°, the third optical filter 354 does not exceed a transmittance of 5% at any wavelength (and has a peak transmittance of about 5% in a wavelength range from about 885nm to about 890nm). Thus, the third optical filter 354 has approximately the same passband as the optical filter 350 at low AOI (eg, an AOI of 0°), but blocks most light at larger AOIs rather than merely shifting the passband as occurs with the first optical filter 350 .

[0044] like Figure 3F As shown, FIG. 310 shows the optical characteristics of the first side (eg, the first component optical filter, such as a bandpass filter) of the third optical filter 354. Figure 3G As shown, Figure 312 shows the optical characteristics of the second side (e.g., a second component optical filter, such as an angle-shifted filter, a high angle-shifted filter, or an angle-sensitive filter) of the third optical filter 354. As shown in Figures 310 and 312, the second side of the second optical filter 354 provides an angular sensitivity greater than the angular sensitivity provided by the first side of the optical filter 354.

[0045] like Figure 3H As shown, Figure 3HA comparison of the integrals of the transmittance of the optical filters 350-354 at incident angles of 0° to 50° is shown. As shown, the first optical filter 350, which does not include an angle-shifting filter, provides a high level of transmittance across the AOI. In contrast, the second optical filter 352 and the third optical filter 354 provide a drop in transmittance at higher AOIs (e.g., AOIs greater than 10°), thereby demonstrating angular sensitivity. Figure 3H In the embodiment, optical filters 352 and 354 transmit greater than a first threshold amount of light within a first configuration angle range and transmit less than a second threshold amount of light within a second configuration angle range. For example, optical filters 352 and / or 354 transmit greater than a threshold percentage (e.g., 50%, 75%, 90%, 95%, or 99%) of light at incident angles in a range of 0° to 10°, 0° to 20°, or 0° to 30°, etc. Conversely, optical filter 352 transmits less than a threshold percentage (e.g., 50%, 25%, 10%, 5%, or 1%) of light at incident angles in a range of 30° to 90°, 40° to 90°, or 50° to 90°, etc.

[0046] As mentioned above, Figure 3A-3H Provided as an example only. Other examples are possible and may be related to Figure 3A-3H Different than described.

[0047] The above disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementation to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementation.

[0048] As used herein, satisfying a threshold may refer to a value being greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc., depending on the context.

[0049] Even if specific feature combinations are listed in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features can be combined in ways that are not specifically listed in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim combined with each other claim in the claim set. As used herein, a phrase referring to "at least one" in a list of items refers to any combination of these items, including single members. For example, "at least one of a, b, or c" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical items.

[0050] Unless explicitly stated, any element, action or instruction used in this article should not be interpreted as key or necessary. In addition, as used in this article, the articles "one" and "an" are intended to include one or more projects, and can be used interchangeably with "one or more". In addition, as used in this article, "the" is intended to include one or more projects related to the article "the", and can be used interchangeably with "one or more", and the term "set" is intended to include one or more projects (for example, related projects, unrelated projects, or a combination of related and unrelated projects), and can be used interchangeably with "one or more". If only one project is intended to be used, the phrase "only one" or similar language is used. In addition, as used in this article, the terms "having", "containing", "including" etc. are intended to be open terms. In addition, unless explicitly stated otherwise, the meaning of the word "based on" is "based at least in part". In addition, as used in this article, the term "or" is inclusive when used in a series, and can be used interchangeably with "and / or", unless explicitly stated otherwise (for example, if used in combination with "either" or "only one").

Claims

1. An optical filter assembly, comprising: a first optical filter disposed on a first side of the substrate, wherein the first optical filter is a bandpass filter; as well as A second optical filter is disposed on a second side of the substrate, wherein the second optical filter is associated with a threshold angular offset at a threshold incident angle. 2 . The optical filter assembly of claim 1 , wherein the second optical filter comprises an anti-reflection filter for a bandpass region of the bandpass filter.

3. The optical filter assembly of claim 1, wherein the second optical filter comprises a long wavelength passband filter.

4. The optical filter assembly of claim 1, wherein the second optical filter comprises a short wavelength passband filter.

5. The optical filter assembly of claim 1, wherein the second optical filter comprises a wide passband filter.

6. The optical filter assembly of claim 1, wherein the first optical filter is a low angle shift (LAS) bandpass filter.

7. The optical filter assembly of claim 1, wherein the first optical filter is a low angle deviation (HLAS) bandpass filter.

8. An optical filter comprising: a bandpass filter having a transmittance of at least a first threshold level at a configured center wavelength, wherein a first side of the bandpass filter is configured to receive a light beam; as well as An angular shift filter having an angular shift of at least a second threshold level at an incident angle greater than a configured value and at a central wavelength of the configuration, wherein the angular shift filter is disposed on a second side of the bandpass filter. 9 . The optical filter according to claim 8 , wherein the bandpass filter comprises one or more high refractive index layers and one or more low refractive index layers arranged alternately.

10. The optical filter of claim 9, wherein the one or more high refractive index layers include at least one of the following: Amorphous silicon layer, or Silicon Hydrogenated Layer.

11. The optical filter according to claim 9, wherein the one or more low refractive index layers include at least one of the following: Silicon oxide layer, Titanium oxide layer, Tantalum oxide layer.

12. The optical filter of claim 8, wherein the angle-shifting filter comprises at least one of the following: Tantalum oxide layer, Titanium oxide layer, Niobium oxide layer, Germanium oxide layer, or Silicon oxide layer.

13. The optical filter of claim 8, wherein the central wavelength of the configuration is in the range of 100 nanometers (nm) to 14,000 nm.

14. The optical filter according to claim 8, wherein the configuration value is in the range of 30 degrees to 90 degrees.

15. An optical system comprising: Electro-optical components; as well as A composite optical filter, comprising: a bandpass filter having a transmittance of at least a first threshold level at a configured center wavelength, wherein a first side of the bandpass filter is configured to receive a light beam; as well as an angular shift filter having an angular shift of at least a second threshold level at an incident angle greater than a configured value and at a central wavelength of the configuration, wherein the angular shift filter is disposed on a second side of the bandpass filter, wherein the composite optical filter is aligned with the electro-optical component, and The composite optical filter is configured to transmit a greater than a first threshold amount of light within a first configuration angle range and to transmit a less than a second threshold amount of light within a second configuration angle range.

16. The optical system of claim 15, wherein the electro-optical component is an optical transmitter configured to transmit at the configured center wavelength.

17. The optical system of claim 15, wherein the electro-optical component is an optical detector configured to detect at the configured center wavelength.

18. The optical system of claim 15, wherein the bandpass filter comprises one or more high refractive index layers and one or more low refractive index layers arranged alternately.

19. The optical system of claim 15, wherein the bandpass filter comprises a substrate, and The angle shift filter is arranged on the substrate.

20. The optical system of claim 19, wherein the substrate is a glass substrate.

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