Optical filter and method for manufacturing optical filter

Abstract

The invention relates to an optical filter and a method for manufacturing the optical filter. An optical filter may include an interference filter having a first material layer and a second material layer stacked on a first side of a substrate. In some examples, the first material layer may include silicon oxide and have a first refractive index, and the second material layer may include a hydrogenated silicon carbide (SiC: H) material having a second refractive index. The SiC: H material layer is defined by a refractive index greater than the silicon oxide material layer in a range of about 1.65 to 4.80. During formation of the SiC: H material layer, a specific refractive index may be adjusted by adjusting the introduction of a gas, such as methane (CH4).

Description

Technical Field

[0001] The present disclosure relates to optical filters and methods of making optical filters. Background Art

[0002] Optical interference filters are typically used in the near-infrared spectrum. Such filters can utilize replicated stacks of layers of different materials having different refractive indices. By employing layers having a relatively high contrast in relative refractive index, angular shifts of the passband center wavelength in such filters can be reduced. However, in order to achieve desired characteristics, the filter may require a large number of layers, thereby increasing the package envelope, cost, and complexity of such filters.

[0003] The subject matter of the present disclosure is directed to overcoming or at least reducing the effects of one or more of the problems set forth above. Summary of the Invention

[0004] According to the present disclosure, an interference filter includes a first material layer stacked on a second material layer. The first material has a first refractive index. The second material includes silicon carbide hydride (SiC:H), and the second material has a second refractive index different from the first refractive index. In some examples, the second refractive index is greater than the first refractive index.

[0005] In some examples, in the spectral range of about 800 nm to 1800 nm, the second refractive index (e.g., of the silicon carbide hydride layer) is in the range of about 1.65 to 4.80.

[0006] According to the disclosed examples, an optical filter includes a substrate (e.g., glass, sapphire, etc.), and alternating layers of a first material layer and a second material layer are stacked on the substrate. The layers alternate between a first refractive index and a second refractive index (e.g., a low refractive index and a high refractive index). In the spectral range of about 800 nm to 1800 nm, the second material layer having the second refractive index can be SiC:H in the range of about 1.65 to 4.80. The first refractive index layer can include one or more of the following (as a non-limiting list of examples): TiO2, Nb2O5, Ta2O5, SiO2, Si x N y , SiH and SiO x H y, where x and y are numerical values. The disclosed optical filter is configured to have a passband in the spectral range of approximately 800 nm to 1800 nm and a blocking level with an optical density (OD) greater than 2 in the spectral range of approximately 300 nm to 600 nm. As used herein, optical density is a measure of the absorbance of light passing through a material and is defined as the ratio of the intensity of light incident on the material to the intensity of the light transmitted through the material.

[0007] According to the disclosed examples, a method of forming a hydrogenated silicon carbide (SiC:H) layer is provided. For example, SiC:H is deposited by sputtering using a silicon sputtering target (or other suitable techniques). An optical filter can be formed using the SiC:H layer, resulting in a smaller angular shift and a lower stack thickness compared to other stacked filters. The SiC:H layer stacked optical filter can also operate at a lower wavelength compared to other interference filters employing Si and SiO2 layers. In some examples, during the formation process, various optical properties of the SiC:H layer can be introduced by fine-tuning the flow rate of methane (CH4).

[0008] These and other features of the present disclosure will become more fully apparent from the following description and the appended claims, as set forth hereinafter.

[0009] The foregoing summary is not intended to outline every potential embodiment or every aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] To further clarify the above and other features of the present disclosure, a more specific description of the subject matter will be presented by reference to specific examples of the subject matter shown in the accompanying drawings. It should be understood that these drawings only depict some examples of the subject matter and should not be considered to limit its scope.

[0011] Figure 1 A schematic diagram of an example optical filter based on hydrogenated silicon carbide according to the present disclosure is shown.

[0012] Figure 2 A schematic diagram of an example sputtering deposition system for fabricating an optical filter based on hydrogenated silicon carbide according to the present disclosure is shown.

[0013] Figure 3A A schematic diagram showing the characterization relationship between the flow rate of methane (CH4) and the transmission spectrum according to the present disclosure, where the x-axis is the wavelength (nm) and the y-axis is the transmittance (%).

[0014] Figure 3B A schematic diagram showing the characterization relationship between the flow rate of methane (CH4) and the absorption threshold wavelength at a 50% transmittance level according to the present disclosure.

[0015] Figure 3C A schematic diagram showing the characterization relationship between the flow rate of methane (CH4) and the refractive index at wavelengths from 500 nm to 1800 nm according to the present disclosure.

[0016] Figure 3D A schematic diagram showing the characterization relationship between the flow rate of methane (CH4) and the refractive index at wavelengths of 750 nm, 905 nm, and 1500 nm according to the present disclosure.

[0017] Figure 3E A schematic diagram showing the characterization relationship between the flow rate of methane (CH4) and the extinction coefficient at wavelengths from 500 nm to 1800 nm according to the present disclosure.

[0018] Figure 4 A schematic diagram showing the transmission spectrum of an optical filter using SiC:H as a high refractive index material at incident angles of 0° and 30° according to the present disclosure, where the x-axis is the wavelength (nm) and the y-axis is the transmittance (%).

[0019] Figure 5 Is a flowchart of a process for fabricating an optical filter according to the present disclosure.

[0020] The accompanying drawings more fully describe the present invention. These drawings may be merely schematic representations of current filters, components, facilities, or methods to enhance understanding of the disclosed concepts. Detailed Description

[0021] Optical filters exhibiting low angular offset, high passband transmittance, and a wide operable wavelength range are disclosed herein. Such optical filters are desirable in various applications, such as three-dimensional sensing technologies that benefit from wide-angle devices. In some exemplary Fabry - Perot type optical filters, the difference in the high and low refractive indices of the alternating layers in the stack can determine the angular offset. Additionally, the extinction coefficient and the absorption threshold wavelength are configured to control the passband transmittance and the lowest operable wavelength of the optical filter, respectively.

[0022] Some exemplary optical filters employ one or more Ta2O5 / SiO2 layers, which are designed to operate in both the visible and near-infrared (IR) spectra. Such devices allow the passband transmittance to reach a high level, but due to the not-too-large difference in refractive indices between the layers, the angular offset of the passband center wavelength is quite large. In the case of Si / SiO2 pairs with a large refractive index silicon layer, the large extinction coefficient of silicon and the long absorption threshold wavelength caused by the small optical bandgap limit the passband transmittance and even applications at lower wavelengths.

[0023] Some solutions seek to prepare silicon hydride by hydrosilylation. One of the disadvantages is that the extinction coefficient of silicon hydride below 900 nm can increase sharply as the wavelength decreases. To some extent, the transmittance of a filter with a passband below 900 nm will be affected. The absorption threshold wavelength of SiC:H near 650 nm exhibits a transmittance level of approximately 50%. Therefore, in the passband below 900 nm, the transmittance level will decrease, and the operating wavelength range will thus be limited.

[0024] Another solution is to use the addition of nitrogen to prepare silicon hydride. One of the disadvantages of this method is that the refractive index of silicon hydride with added nitrogen is in a limited range of 1.9 to 2.7, which is less than that of silicon hydride with a refractive index greater than 3. Therefore, the angular shift of the central wavelength is not small enough for many desired applications.

[0025] Therefore, there is great interest in preparing a material with a refractive index greater than that of silicon, a smaller extinction coefficient, and a higher absorption threshold wavelength for the optical filters mentioned above.

[0026] The disclosed optical filters benefit from the properties of SiC:H, and layers of SiC:H can be prepared by the disclosed methods and systems. The resulting layers of SiC:H produce refractive indices in a wide range of approximately 1.65 to 4.80 in a broad spectral range of approximately 800 nm to 1800 nm.

[0027] Using alternating layers of silicon and silicon dioxide, the disclosed optical filters offer many advantages, including that the number of alternating layers in the stack is greatly reduced (e.g., almost halved) compared to optical filters including stacks of alternating Ta2O5 and silicon dioxide layers.

[0028] In some examples, a method of fabricating an optical filter uses a sputtering system to deposit a layer of SiC:H on a clean substrate. In such a method, a high-refractive-index layer of SiC:H is deposited by sputtering using a silicon sputtering target, where the flow rate of methane (CH4) can be adjusted to customize one or more optical properties of the SiC:H material layer.

[0029] The SiC:H material layer exhibits a high refractive index and is often paired with another material layer (e.g., SiO2) in the stack in an alternating layer pattern. The optical filter can have a smaller angular shift and a lower stack thickness than traditional filters. Compared to interference filters using only Si and SiO2 layers, it can also extend the application to smaller wavelengths. The present disclosure provides various methods for diversifying the optical properties of the technologically required silicon carbide hydride (SiC:H) layer by fine-tuning the flow rate of methane (CH4).

[0030] In some examples, the first side of the band - pass filter is a filter stack composed of alternating layers of a high - refractive - index material and a low - refractive - index material. The high - refractive - index material is hydrogenated silicon carbide (SiC:H), and has a refractive index of 3.46 near 905 nm. An example of the low - refractive - index material is SiO2, which has a refractive index of 1.46 near 905 nm. The total number of layers of the filter stack can be 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 or more. For a stack with 22 layers, the total physical thickness can be approximately 3.7 microns. The steepness of the transition band and the blocking depth of the filter stack are determined by the first side.

[0031] The disclosed band - pass filter is configured to have a pass - band in the spectral range of approximately 800 nm to approximately 1800 nm. In the band - pass filter, the angular shift of the center wavelength is approximately 13 nm at an incident angle changing from about 0° to 30°. The band - pass filter can be associated with a band - pass centered at approximately 950 nm, and can be associated with a full - width at half - maximum (FWHM) of the band - pass of approximately 50 nm at an incident angle of 0°.

[0032] As used herein, a band - pass filter is an optical filter configured to selectively transmit a portion of the incident spectrum while suppressing all other wavelengths. The transmitted portion can be referred to as the pass - band frequency.

[0033] As used herein, the transmittance of a material corresponds to the effectiveness of the material in transmitting radiant energy and is typically defined as a percentage of the incident spectrum.

[0034] In the examples described below, the optical filter is provided with hydrogenated silicon carbide (SiC:H) as the high - refractive - index material, resulting in a smaller angular shift, a lower absorption threshold wavelength, and a smaller stack thickness compared to other solutions (e.g., optical filters using Ta2O5).

[0035] Turning to the drawings, Figure 1 An example optical filter 100 (such as an interference filter) is shown, including alternating layers of hydrogenated silicon carbide (SiC:H) and silicon dioxide (SiO2). Here, the SiO2 layer has a first refractive index smaller than that of the SiC:H layer. As Figure 1 provided, the optical filter 100 includes a substrate 110 (e.g., a clean substrate) and an optical filter stack 120. The optical filter stack 120 includes a plurality of high - refractive - index layers 121 - 1 to 121 - n (where n>2) and a plurality of low - refractive - index layers 122 - 1 to 122 - n (where n>2).

[0036] In some examples, layer 121 may include SiC:H material. In the spectral range of approximately 800 nm to 1800 nm, the refractive index of layer 121 ranges from approximately 1.65 to 4.80. Layer 122 may include SiO2 material. Additionally or alternatively, layer 122 may include one or more of the following materials (as a non-limiting list of examples), including TiO2, Nb2O5, Ta2O5, SiO2, Si x N y and SiO x H y . Figure 1 The number of layers and the stacking order of the optical filters provided in Figure 1 are for illustrative purposes only and may be designed to include more or fewer alternating pairs of layered materials depending on the requirements of a particular application.

[0037] In the disclosed examples, the optical filter stack 120 may be deposited on a surface by vacuum sputter deposition. As shown in the example of Figure 2 , a medium frequency (MF) magnetron sputtering system 200 may be used to deposit one or more material layers to form the optical filter stack 120. The sputtering system 200 includes a chamber 201 connected to a vacuum pumping system 202, which may be or include (as a non-limiting list of examples) one or more mechanical pumps, diffusion pumps, cryopumps, and / or turbomolecular pumps. In some examples, the vacuum pumping system 202 is a combination of a mechanical pump and a turbomolecular pump. The MF power supply 203 may include one or more lines to the sputtering target 206. The power supply 203 may generate an output power in the kW range or close to the kW range, with a frequency of approximately 5 to 100 kHz. In some examples, the output power of the power supply 203 is between approximately 8 kW and 10 kW, and the operating frequency is approximately 40 kHz.

[0038] Figure 2 The sputtering unit 200 in Figure 1The substrate 110) in is oriented towards the target 205 for the deposition of the material layer. One or more gases such as O2, Ar2, and / or methane (CH4) can be used, corresponding to gas 207, gas 208, and gas 209 respectively. These gases enter the vicinity of the sputtering unit 200 in the chamber 201 through pipes connecting the gas sources to the chamber. The pipes are equipped with one or more flow meters to regulate and monitor the gas flow entering the chamber 201. In some examples, the system 200 is equipped with an auxiliary plasma source 211. The gas can enter the chamber partially or entirely through the auxiliary plasma source 211 to increase plasma activation and improve film formation quality.

[0039] Through this system and process, a stacked optical filter with alternating material layers can be achieved. When generating the SiC:H layer, the silicon absorption threshold blueshifts with the increase in hydrogen concentration, and a passband of an optical filter with a spectral range of approximately 800 nm to 1200 nm can be achieved. The SiC:H layer has strong absorption at wavelengths below 600 nm, which results in a high blocking level below 600 nm.

[0040] Although magnetron sputtering deposition is described herein, other deposition methods such as ion beam sputtering are also contemplated. Different materials with different properties may also be used for specific applications.

[0041] Figures 3A to 3E A diagram showing the characteristics of the SiC:H single layer film is provided. Figure 3A The graph 300 shown in shows the relationship between the flow rate of methane (CH4) during the deposition process and the transmission spectrum of the single layer SiC:H film in the spectral range of approximately 300 nm to 1800 nm. Here, the x-axis represents the wavelength (nm) and the y-axis is the transmittance (T%).

[0042] The example films 301 to 305 are single layer films with an optical thickness of approximately 3.5 quarter wavelengths at a wavelength of approximately 950 nm. The flow rate of the gas (e.g., from the CH4 gas source 209) continuously increases in the films 301 to 307, corresponding to 5 sccm, 15 sccm, 25 sccm, 30 sccm, and 50 sccm respectively. As shown in the graph 300, in the spectral range of approximately 600 nm to 750 nm, the spectral peaks of the films 301 to 305 are approximately 30.0%, 61.7%, 83.6%, 87.2%, and 92.1% respectively. In addition, in the spectral range of approximately 600 - 750 nm, the transmittance of the films 301 to 305 increases with the increase in the CH4 flow rate. In other words, below 750 nm, the transmittance is positively correlated with the introduction of CH4.

[0043] Figure 3BThe graph 308 shown in [the figure] shows the relationship between the flow rate of CH4 and the absorption threshold wavelength at a transmittance level of approximately 50%, where the x-axis is the wavelength (nm) and the y-axis is the flow rate of methane (sccm). Additionally, at a transmittance level of approximately 50%, by increasing the CH4 flow rate, the absorption threshold wavelength decreases from approximately 800 nm to approximately 530 nm. Compared with SiC:H (where the absorption threshold is approximately 650 nm at a transmittance level of 50%), SiC:H has a further reduced absorption threshold wavelength.

[0044] Figure 3C The graph 310 shown in [the figure] shows the relationship between the flow rate of CH4 and the refractive indices of several materials at wavelengths from approximately 500 nm to approximately 1800 nm. The flow rate of CH4 (e.g., gas 209) continuously increases during the formation of films 311 to 315, corresponding to 5 sccm, 15 sccm, 25 sccm, 30 sccm, and 50 sccm, respectively. In the spectral range from approximately 800 nm to approximately 1800 nm, the refractive indices of films 311 to 315 are greater than approximately 3.58, 3.29, 3.02, 2.88, and 2.43, respectively.

[0045] Figure 3D The graph 318 shown in [the figure] shows the relationship between the flow rate of CH4 and the refractive indices at wavelengths of approximately 750 nm, 905 nm, and 1500 nm. In other words, the refractive index of SiC:H shows a downward trend as the CH4 flow rate increases.

[0046] Figure 3E The graph 320 shown in [the figure] shows the relationship between the flow rate of CH4 and the extinction coefficients at wavelengths from approximately 500 nm to 1800 nm. The flow rate of CH4 (e.g., gas 209) continuously increases in films 321 to 325, corresponding to 5 sccm, 15 sccm, 25 sccm, 30 sccm, and 50 sccm, respectively. Additionally, in the spectral range from approximately 750 nm to approximately 1800 nm, the extinction coefficients of films 321 to 327 are less than approximately 0.04691, 0.01420, 0.00280, 0.00203, and 0.00002, respectively, and in the spectral range from approximately 800 nm to approximately 1800 nm, they are less than approximately 0.02628, 0.00666, 0.00112, 0.00118, and 0.00001, respectively. As Figure 3E shown, the extinction coefficient decreases as the CH4 flow rate increases.

[0047] According to the disclosed examples, one or more optical properties of SiC:H can be customized by adjusting the flow rate of CH4. For example, the refractive index n and extinction coefficient k of SiC:H can be decreased by increasing the flow rate of CH4 during deposition. The refractive index n and extinction coefficient k of the SiC:H material can be increased by decreasing the flow rate of CH4 during deposition. High transmittance uses a relatively large amount of CH4 to achieve a low extinction coefficient, while small angular shift uses a relatively small amount of CH4 to obtain a high refractive index. In other words, applying a small amount of CH4 during deposition may result in a decrease in the transmittance through the filter passband but with a small angular shift, while a large amount of CH4 exhibits the opposite results (e.g., an increase in transmittance and a larger angular shift). Therefore, there is a trade-off between the refractive index and extinction coefficient of the material.

[0048] In some examples, it may be difficult to customize the refractive index of the SiC:H material at around a wavelength of 905 nm in the range of 1.65 to 3.9 solely by adjusting the CH4 flow rate. Empirically, the limit of the refractive index adjustment range near about 905 nm is approximately between 2.3 and 3.8. Additionally, the choice of the CH4 flow rate is affected by the vacuum pumping speed of the sputtering system 200, the sputtering power of the target, and the flow rate of the working gas. When adjusting the refractive index of the material by changing parameters such as the sputtering power (e.g., sputtering efficiency) and the working gas (e.g., the flow rate of Ar2 from gas 208), the basic principle is similar to that described for the adjustment of the CH4 flow rate.

[0049] Based on the above monolayer data, an interference filter composed of the SiC:H material has good performance in the working wavelength range of approximately 800 nm to approximately 1800 nm, and can even extend the working wavelength range to approximately 750 nm or less.

[0050] Figure 4 Chart 401 showing characteristics related to an optical filter using SiC:H as a high refractive index material is presented. Chart 401 shows the transmission spectra of an optical filter using SiC:H as the high refractive index at incident angles of approximately 0° and 30°, where the x-axis is the wavelength (nm) and the y-axis is the transmittance (T%). The bandpass filter 401 includes a stack having one or more pairs of layers, each layer having a SiC:H layer and a SiO2 layer. In some examples, one or more pairs of layers may include an antireflection layer or be arranged near the antireflection layer.

[0051] In some examples, the bandpass filter 401 is a filter stack having a first side composed of alternating layers of a high refractive index material and a low refractive index material (e.g., similar to Figure 1 the layers 121 and 122 shown in the optical filter 100 in Figure 4In an example, the high refractive index material (SiC:H) has a refractive index of approximately 3.46 near 905 nm. The low refractive index material (SiO2) has a refractive index of approximately 1.46 near 905 nm. In some examples, the filter stack has a total of 22 layers, and the total physical thickness is approximately 3.7 microns.

[0052] The sharpness (e.g., steepness) of the rise of the transition band and the blocking depth of the filter stack are determined by a first side composed of alternating material layers. The design of the filter stack is defined by 5 cavities. For a steeper slope, the number of cavities can be increased. In other words, the number of layers within the filter stack increases, which may increase the manufacturing difficulty.

[0053] On the second side of the band - pass filter 401, an antireflection (AR) coating stack is deposited to achieve improved transmission of the pass - band around 950 nm and reduce the reflection of the back surface. In some examples, the AR coating stack is alternately stacked with one or more of Ta2O5 layers and SiO2 layers. In an example, the AR coating stack includes 5 layers.

[0054] The disclosed band - pass filter 401 is configured to have a pass - band in the spectral range of approximately 800 nm to approximately 1800 nm. In the band - pass filter 401, at an incident angle changing from about 0° to 30°, the angular shift of the center wavelength is approximately 13 nm. The band - pass filter 401 can be associated with a band - pass centered at approximately 950 nm and can be associated with a full - width at half - maximum (FWHM) of the band - pass of approximately 50 nm at an incident angle of 0°.

[0055] Compared with traditional filters using SiO2 and Ta2O5 as layer materials, the disclosed band - pass filter 401 using a high refractive index (such as SiC:H) has significant advantages. For example, the number of layers of the band - pass coating is significantly reduced (e.g., by more than half), and the resulting filter produces a smaller angular drift. This means that the manufacturing of the band - pass filter 401 is relatively simple, resulting in a filter with high production efficiency, large production volume, and good filtering performance.

[0056] Figure 5 is a flowchart of a process for fabricating an optical filter according to an example embodiment of the present disclosure. The process, as shown in the flowchart in Figure 5 starts from step 501, where a substrate (e.g., a clean substrate) is arranged in the chamber of a sputtering system. In step 502, one or more gases are introduced into the chamber.

[0057] In step 503, one or more silicon sputtering targets are oriented towards the substrate. In step 504, the sputtering system is activated to deposit one or more silicon carbide (SiC:H) material layers onto the substrate. In step 505, the sputtering system is activated to deposit one or more layers of silicon material (e.g., TiO2, Nb2O5, Ta2O5, SiO2, Si x N y or SiO x H y ) onto the substrate. For example, the SiC:H and silicon material layers may be alternated to form a stack, which may include 22 layers, or more, or less.

[0058] In step 506, the flow rate of one or more gases is adjusted to customize one or more optical properties of the SiC:H material layer (and / or one or more optical properties of the silicon material layer). In some examples, one or more gases include methane (CH4). The resulting optical filter includes multiple SiC:H layers that exhibit the desired optical properties (including a refractive index in the range of approximately 1.65 to 4.80).

[0059] In the disclosed examples, the optical filter includes a substrate and an interference filter, the interference filter including a first material layer and a second material layer stacked on a first side of the substrate, wherein the first material layer includes silicon oxide and has a first refractive index, and the second material layer includes a silicon carbide (SiC:H) material having a second refractive index.

[0060] In some examples, the first refractive index of the first material layer is less than the second refractive index of the second material layer.

[0061] In some examples, in a broad spectral range of approximately 800 nm to 1800 nm, the second refractive index of the SiC:H material is in the range of approximately 1.65 to 4.80.

[0062] In some examples, the first material layer includes one or more of TiO2, Nb2O5, Ta2O5, SiO2, Si x N y and SiO x H y .

[0063] In some examples, the optical filter includes one or more antireflection layers.

[0064] In some examples, the interference filter includes multiple alternating pairs of the first material layer and the second material layer arranged as a stack on the substrate.

[0065] In some examples, the substrate includes a transparent glass material.

[0066] In some examples, the interference filter is configured to produce a passband in the range between 800 nm and 1800 nm.

[0067] In some examples, the optical filter is configured to produce a blocking level with an optical density greater than 2 in a given spectral range.

[0068] In an example, the given spectral range is between 300 nm and 600 nm.

[0069] In some disclosed examples, a method of fabricating an optical filter includes: disposing a substrate within a chamber of a sputtering system; introducing one or more gases into the chamber; orienting one or more silicon sputtering targets towards the substrate; and activating the sputtering system to deposit one or more layers of silicon carbide hydrogen (SiC:H) material onto the substrate.

[0070] In some examples, the method further includes: adjusting the flow rate of one or more gases to customize the optical properties of one or more SiC:H material layers.

[0071] In some examples, one or more gases include methane (CH4).

[0072] In some examples, the optical properties of the SiC:H material layer include a refractive index in the range of approximately 1.65 to 4.80.

[0073] In some examples, the sputtering system is a magnetron sputtering deposition system.

[0074] In some examples, the sputtering system is a sputtering deposition system.

[0075] In some examples, the optical filter includes a first layer of a first material deposited on a substrate, and a second layer of a second material stacked on the first layer opposite the substrate, wherein the second material is a silicon carbide hydrogen (SiC:H) material.

[0076] In some examples, the first material layer has a first refractive index, and the second material layer has a second refractive index greater than the first refractive index.

[0077] In some examples, in a broad spectral range of approximately 800 nm to 1800 nm, the second refractive index of the SiC:H material is in the range of approximately 1.65 to 4.80.

[0078] In some examples, the first material layer includes one or more of TiO2, Nb2O5, Ta2O5, SiO2, Si x N y and SiO x H y among others.

[0079] In the drawings, like features are always denoted by the same reference numerals.

[0080] The foregoing description of the preferred embodiments and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concept conceived by the applicant. With respect to the rights of the present disclosure, it will be understood that in any other embodiment or aspect of the disclosed subject matter, the features described above in accordance with any embodiment or aspect of the disclosed subject matter may be used alone or in combination with any other described feature.

Claims

1. An optical filter, comprising: a substrate; and an interference filter including a first material layer and a second material layer stacked on a first side of the substrate, wherein the first material layer comprises silicon oxide and has a first refractive index, and the second material layer comprises a hydrogenated silicon carbide material having a second refractive index.

2. The optical filter according to claim 1, wherein, The first refractive index of the first material layer is less than the second refractive index of the second material layer.

3. The optical filter according to claim 2, wherein In a wide spectral range from 800 nm to 1800 nm, the second refractive index of the hydrogenated silicon carbide material is in the range of 1.65 to 4.

80.

4. The optical filter according to claim 1, wherein The first material layer includes one or more of TiO2, Nb2O5, Ta2O5, SiO2, Si x N y and SiO x H y among others.

5. The optical filter according to claim 1, further comprising one or more anti-reflection layers.

6. The optical filter according to claim 1, wherein, The interference filter includes a plurality of alternating pairs of the first material layer and the second material layer arranged as a stack on the substrate.

7. The optical filter according to claim 1, wherein, The substrate comprises a transparent glass material.

8. The optical filter according to claim 1, wherein, The interference filter is configured to produce a passband in the range between 800 nm and 1800 nm.

9. The optical filter according to claim 1, wherein, The optical filter is configured to produce a blocking level with an optical density greater than 2 in a given spectral range.

10. The optical filter according to claim 9, wherein, The given spectral range is between 300 nm and 600 nm.

11. A method of fabricating an optical filter, comprising: placing a substrate in a chamber of a sputtering system; introducing one or more gases into the chamber; orienting one or more silicon sputtering targets towards the substrate; and activating the sputtering system to deposit one or more hydrogenated silicon carbide material layers on the substrate.

12. The method according to claim 11 further comprises: Adjusting the flow rate of the one or more gases to customize the optical properties of the one or more hydrogenated silicon carbide material layers.

13. The method according to claim 12, wherein, The one or more gases include methane (CH4).

14. The method according to claim 12, wherein, The optical properties of the hydrogenated silicon carbide material layer include a refractive index in the range of 1.65 to 4.

80.

15. The method according to claim 11, wherein, The sputtering system is a magnetron sputtering deposition system.

16. The method according to claim 11, wherein, The sputtering system is a sputtering deposition system.

17. An optical filter, comprising: a first layer of a first material deposited on a substrate; and a second layer of a second material stacked on the first layer opposite to the substrate, wherein the second material is a hydrogenated silicon carbide material.

18. The optical filter according to claim 17, wherein, The first material layer has a first refractive index, and the second material layer has a second refractive index greater than the first refractive index.

19. The optical filter according to claim 17, wherein, In a wide spectral range from 800 nm to 1800 nm, the second refractive index of the hydrogenated silicon carbide material is in the range of 1.65 to 4.

80.

20. The optical filter according to claim 17, wherein, The first material layer includes one or more of TiO2, Nb2O5, Ta2O5, SiO2, Si x N y and SiO x H y in it.

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