CN111736249B - Infrared bandpass filter and sensor system - Google Patents

Infrared bandpass filter and sensor system Download PDF

Info

Publication number
CN111736249B
CN111736249B CN202010825667.0A CN202010825667A CN111736249B CN 111736249 B CN111736249 B CN 111736249B CN 202010825667 A CN202010825667 A CN 202010825667A CN 111736249 B CN111736249 B CN 111736249B
Authority
CN
China
Prior art keywords
filter
infrared
band
refractive index
bandpass filter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202010825667.0A
Other languages
Chinese (zh)
Other versions
CN111736249A (en
Inventor
纪登鑫
沈健
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Goodix Technology Co Ltd
Original Assignee
Shenzhen Goodix Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Goodix Technology Co Ltd filed Critical Shenzhen Goodix Technology Co Ltd
Priority to CN202010825667.0A priority Critical patent/CN111736249B/en
Publication of CN111736249A publication Critical patent/CN111736249A/en
Application granted granted Critical
Publication of CN111736249B publication Critical patent/CN111736249B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/201—Filters in the form of arrays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G01S17/894—3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/208—Filters for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Optical Filters (AREA)

Abstract

The present application provides an optical filter, comprising: a substrate; and a filter stack disposed on at least one side of the substrate, wherein the filter stack includes a plurality of MoS2A layer and a plurality of low refractive index layers, the plurality of MoS2A layer and the plurality of low refractive index layers are alternately stacked, the low refractive index layer having a refractive index less than the MoS2The refractive index of the layer.

Description

Infrared bandpass filter and sensor system
Technical Field
Embodiments of the present application relate to the field of optics, and more particularly, to infrared bandpass filters and sensor systems.
Background
Infrared bandpass filters are important optical devices and are widely used in a variety of applications. For example, in Time of Flight (TOF) based three-dimensional detection, a near-infrared band-pass filter is usually used to block ambient light, so as to reduce the influence of light in non-target wavelength bands on the signal-to-noise ratio of the sensor as much as possible while ensuring the transmittance of light in the target wavelength band. For another example, in the field of optical communications, it is also necessary to use a near-infrared band-pass filter including an optical communication wavelength in a pass band. With the wide application of the infrared band-pass filter, the performance of the infrared band-pass filter needs to be improved urgently at present.
Disclosure of Invention
The embodiment of the application provides an infrared band-pass filter and a sensor system, wherein the infrared band-pass filter has better performance.
In a first aspect, an infrared bandpass filter is provided, the filter comprising:
a substrate; and the number of the first and second groups,
a filter stack disposed on at least one side of the substrate, wherein the filter stack includes a plurality of molybdenum sulfide MoS alternately stacked2A layer and a plurality of low refractive index layers having a refractive index less than the MoS2The refractive index of the layer.
In one possible implementation manner, the transmittance of the pass band of the infrared band-pass filter is greater than 90%, the optical density OD of the visible light band of the stop band of the infrared band-pass filter is greater than 3, and the OD of the infrared band of the stop band of the infrared band-pass filter is greater than 2.
In one possible implementation, the passband of the infrared bandpass filter at least partially overlaps with a wavelength range of 800nm to 2000 nm.
In one possible implementation, the MoS2The refractive index of the layer is between 3.5 and 5.
In one possible implementation, the MoS2Extinction coefficient of the layer being less than 5 x 10-3。
In one possible implementation, the MoS2The layers are formed by evaporation.
In one possible implementation, the low refractive index layer is composed of one or more of the following materials: silicon dioxide SiO2Magnesium fluoride MgF, aluminum fluoride AlF, titanium dioxide TiO2Aluminum oxide Al2O3Niobium pentoxide Nb2O5Ta, tantalum pentoxide2O5。
In one possible implementation, the low refractive index layer has a refractive index of less than 2.5.
In one possible implementation, the filter stack is disposed on either the upper surface side or the lower surface side of the substrate.
In one possible implementation, the plurality of MoSs2The total number of layers and the plurality of low refractive index layers is 47 layers and the total thickness is 7.2 um.
In one possible implementation, the wavelength of the passband of the infrared bandpass filter comprises 1550 nm.
In one possible implementation, the infrared band-pass filter has a passband whose center wavelength shifts by less than 30nm when the angle of incidence of the light varies between 0 ° and 30 °.
In one possible implementation manner, the OD of the visible light band of the stop band of the infrared band-pass filter is greater than 39, and the OD of the infrared band of the stop band of the infrared band-pass filter is greater than 2.2.
In one possible implementation, the infrared band-pass filter has a passband with a transmittance greater than 99%.
In one possible implementation, the infrared band pass filter further includes: and the light absorption coating is arranged on the other side of the substrate and used for blocking light rays in a waveband of a stop band of the infrared band-pass filter.
In one possible implementation, the filter stack is disposed on two sides of the substrate, the filter stack forms a high-pass filter portion and a low-pass filter portion in portions located on two sides of the substrate, respectively, and a pass band of the filter is an overlapping portion of a pass band of the high-pass filter portion and a pass band of the low-pass filter portion.
In one possible implementation, the high-pass filter portion includes the plurality of MoS2The total number of layers and the plurality of low refractive index layers is 47 and the total thickness is 4.5 um; the plurality of MoSs included in the low-pass filter section2The total number of layers and the plurality of low refractive index layers is 23 layers and the total thickness is 4.9 um.
In one possible implementation, the wavelength of the passband of the infrared bandpass filter comprises 940 nm.
In one possible implementation, the infrared band-pass filter has a passband whose center wavelength shifts by less than 10nm when the angle of incidence of the light varies between 0 ° and 30 °.
In one possible implementation, the infrared band-pass filter has a passband with a transmittance greater than 99%.
In one possible implementation, the optical filter is applied in three-dimensional detection based on TOF or structured-light (structured-light), or in optical communication.
In a second aspect, there is provided a sensor system comprising:
a light source for emitting light;
the infrared band-pass filter in the first aspect or any possible implementation manner of the first aspect, the infrared band-pass filter being configured to transmit a portion of the light emitted by the light source, the portion being located within a pass band of the infrared band-pass filter; and the number of the first and second groups,
and the sensor is used for detecting the light transmitted by the infrared band-pass filter.
In a possible implementation, the sensor system is applied in three-dimensional detection based on TOF or structured light, or in optical communication.
Based on the technical scheme, the semiconductor material MoS is prepared2Application in the optical field, in particular to MoS2As a material for the high refractive index layer in the infrared band pass filter, a high refractive index material layer and a low refractive index layer are alternately stacked to form a filter stack, so as to realize a high-performance infrared band pass filter. The infrared band-pass filter has small central wavelength deviation when the incident angle of light changes, and has high transmittance in a pass band.
Drawings
Fig. 1 is a schematic structural diagram of a possible infrared band-pass filter according to an embodiment of the present disclosure.
Fig. 2 is a schematic structural diagram of another possible infrared band-pass filter according to an embodiment of the present disclosure.
Fig. 3 is a schematic structural diagram of yet another possible infrared band-pass filter according to an embodiment of the present application.
FIG. 4 is a MoS2Refractive index and extinction coefficient of (a).
Fig. 5 is a schematic diagram of an infrared bandpass filter according to an embodiment of the present application.
FIG. 6 is based on Si-H/SiO shown in FIG. 22Schematic diagram of transmittance curve of the filter.
FIG. 7 is based on the MoS shown in FIG. 22/SiO2Schematic diagram of transmittance curve of the filter.
FIG. 8 is a graph based on Si in H/SiO shown in FIG. 12Schematic diagram of transmittance curve of the filter.
FIG. 9 is based on the MoS shown in FIG. 12/SiO2Schematic diagram of transmittance curve of the filter.
Fig. 10 is an enlarged view of the filter shown in fig. 9 at the pass band.
Fig. 11 is an enlarged view of the filter shown in fig. 9 at the stop band.
FIG. 12 is a schematic diagram of a sensor system of an embodiment of the present application.
Detailed Description
The technical solution of the present application will be described below with reference to the accompanying drawings.
Fig. 1 to 3 show schematic structural diagrams of several possible types of infrared bandpass filters according to embodiments of the present application. In general, an infrared bandpass filter includes at least a substrate and a filter stack, hereinafter also referred to simply as a filter stack, disposed on the substrate, such as shown in fig. 1. The filter stack is typically formed of alternating layers of high and low refractive index, i.e., alternating layers of high and low refractive index are formed on a substrate in sequence. Among them, the layer (innermost layer) directly contacting the substrate may be a high refractive index layer or a low refractive index layer; the layer furthest from the substrate (the outermost layer) is typically a low refractive index layer and incident light may be incident on the infrared band pass filter, for example, from the outermost low refractive index layer, thereby filtering light in non-target bands and transmitting light in target bands. It should be understood that the high refractive index and the low refractive index in the embodiments of the present application are relative cases, and the refractive index n of the material of the high refractive index layer is satisfiedhGreater than the refractive index n of the material of the low-refractive-index layerlI.e. nh＞nlAnd (4) finishing. The high and low index layers are typically formed using different dielectric materials, for example, the infrared bandpass filter may include Si: H/SiO2A filter stack in which the high refractive index layer is composed of silicon hydride (Si: H) and the low refractive index layer is composed of SiO2And (4) forming. In addition, it is to be understood that, for the high refractive index layer and the low refractive index layer alternately disposed, a single material layer formed using a process such as evaporation; it may also refer to a plurality of material layers formed of the same material, i.e., a high refractive index layer or a low refractive index layer having a multi-layer structure, thereby realizing a functional "single" layer of the high refractive index layer or a "single" layer of the low refractive index layer.
In the infrared bandpass filter shown in fig. 1, the filter stack is disposed on only one side of the substrate, but the filter stack may also be disposed on both sides of the substrate, depending on the application and performance requirements, as shown, for example, in fig. 2. In fig. 2, the infrared band pass filter includes filter stacks coated on the upper and lower surfaces of a substrate, respectively. Generally, the infrared band-pass filter of this design includes a high-pass filter and a low-pass filter, and the band of the overlap between the pass band of the high-pass filter and the pass band of the low-pass filter is the band-pass band of the infrared band-pass filter.
In other applications, the infrared bandpass filter may further include a filter stack applied to one side of the substrate, and a light-absorbing coating, such as a visible light-absorbing coating, on the other side of the substrate, such as shown in fig. 3. The light absorption coating can effectively improve the Optical Density (OD) value of the band-stop band, reduce the light transmittance of the band-stop band and improve the signal-to-noise ratio.
The basic requirement of the infrared band-pass filter is to have high transmittance in the pass band and high light-blocking rate outside the pass band, i.e. in the stop band, wherein the OD value can be used to represent the light-blocking rate of the stop band, and the larger the OD value, the higher the light-blocking rate, the better the light-blocking capability.
In addition, in the case of the infrared band pass filter, when the incident angle of the light is changed, the central wavelength of the passband of the infrared band pass filter is shifted accordingly. To reduce the shift in center wavelength, the width of the passband can be increased so that light of the target wavelength within the desired range of incident angles is within the passband of the filter. However, such designs tend to transmit increased ambient light, thereby reducing the signal-to-noise ratio, and increasing the width of the passband typically requires an increase in the number of filter stacks, for example typically about 120-225 layers. The increased number of filter stacks affects the cost and fabrication time of the filter, and the greater total stack thickness also makes it difficult to pattern the filter.
To this end, the present application provides an infrared band pass filter having superior performance, in particular, a small shift of the center wavelength of the pass band when the incident angle of light is changed, and a large transmittance in the pass band without increasing the thickness of the filter stack of the infrared band pass filter.
The infrared band pass filter of the embodiment of the present application may be applied in various scenarios, for example, in distance detection, Time of Flight (TOF) or structured light based three-dimensional detection, or optical communication.
Fig. 4 is a schematic block diagram of the structure of an infrared band-pass filter of an embodiment of the present application. As shown in fig. 4, the infrared bandpass filter 400 includes a substrate 410 and a filter stack 420.
The passband of the infrared bandpass filter 400 may at least partially overlap with the wavelength range of 800nm to 2000 nm. For example, the wavelength of the pass band of the infrared band-pass filter 400 may include 940nm, or the center wavelength of the infrared band-pass filter 400 is around 940nm, such as it is applied in three-dimensional detection based on TOF; alternatively, the wavelength of the passband of the infrared bandpass filter 400 may comprise 1550nm, or the center wavelength of the infrared bandpass filter 400 is around 1550nm, such as for use in optical communications.
Wherein the filter stack 420 is disposed on at least one side of the substrate 410.
The filter stack 420 includes a plurality of MoS's alternately stacked2A layer and a plurality of low refractive index layers.
Wherein the low refractive index layer has a refractive index less than that of the MoS2The refractive index of the layer. In other words, the material of each high refractive index layer in the filter stack 420 is MoS2The material of each low refractive index layer in the filter stack 420 is a low refractive index material, the MoS2Is higher than the refractive index of the low refractive material.
MoS2Referred to as molybdenum sulphide or disulfide, MoS2The material is a semiconductor material which has good lubricity and is resistant to pressure and abrasion, so that the material is generally used as a solid lubricant for equipment operated under working conditions such as high speed, heavy load, high temperature, high vacuum and chemical corrosion. Furthermore, MoS2Also has diamagnetic properties, and can be used as linear photoconductors and semiconductors exhibiting P-type or N-type conductivityAnd the conductor has the functions of rectification and transduction. MoS2It can also be used as a catalyst for the dehydrogenation of complex hydrocarbons. However, for MoS2Has very few applications in the optical field, and also only utilizes single-layer or ultra-thin MoS2As a two-dimensional optical material, a filter stack of an infrared band-pass filter has never been produced by utilizing its high refractive index characteristic.
MoS2The material has a high refractive index, for example, in the wavelength range of 800nm to 2000nm, which lies between 3.5 and 5, and even up to 4 and 5. MoS2The extinction coefficient of the material is also low, e.g. less than 5X 10 in the wavelength range of 800nm to 2000nm-3。
First table is MoS2The comparison of Si to H shows that MoS is present at different wavelengths2The refractive index of the material is obviously higher than that of Si and H materials. FIG. 5 shows MoS2The refractive index and extinction coefficient of the material vary with wavelength, as can be seen, MoS2The material has a high refractive index (n) and a small extinction coefficient (k) in the wavelength range of 800nm to 2000 nm.
Watch 1
Figure 446157DEST_PATH_IMAGE001
The material of the low refractive index layer typically has a small refractive index, for example, typically a refractive index of less than 2.5.
The material of the low refractive index layer is not limited in the embodiments of the present application, as long as the refractive index of the material is less than MoS2The refractive index of (2) is sufficient. For example, the material of the low refractive index layer may consist of one or more of the following materials: silicon dioxide SiO2Magnesium fluoride MgF, aluminum fluoride AlF, titanium dioxide TiO2Aluminum oxide Al2O3Niobium pentoxide Nb2O5Ta, tantalum pentoxide2O5. To optimize the performance of infrared bandpass filter 400, for exampleThe refractive index and MoS can be selected2The low index material is much different. Preferably, the material of the low refractive index layer may be SiO2。
In this example, a semiconductor material MoS was used2The material is applied to the optical field, and particularly used as a material of a high-refractive-index layer in an infrared band-pass filter, so that the material and the low-refractive-index layer are alternately stacked to form a filtering stack, and the high-performance infrared band-pass filter can be realized. The infrared band-pass filter has small central wavelength deviation when the incident angle of light changes, and has high transmittance in a pass band.
The use of MoS is described in detail below2As a principle of the material of the high refractive index layer in the filter stack. See the following equation (1), wherein RAVEIs the lowest average reflectivity within the passband of the infrared bandpass filter; b = λmax/λmin，λmaxAnd λminRespectively the maximum wavelength and the minimum wavelength corresponding to the pass band; t is the total thickness of the high and low refractive index layers, L is the refractive index of the outermost layer of the filter stack, which is typically a low refractive index layer, thereby reducing RAVE；D=nh-nlThe difference between high and low refractive index.
Figure 575787DEST_PATH_IMAGE002
As can be seen from equation (1), at a fixed bandwidth B and low index of refraction material nlIn the case of (2), in order to reduce the reflectance in the pass band of the infrared band-pass filter, it is necessary to increase the total thickness L of the high-refractive-index layer and the low-refractive-index layer, or to increase the refractive-index difference D between the high-refractive-index layer and the low-refractive-index layer. Increasing L results in cost and manufacturing time for the infrared bandpass filter, so finding a higher index material is the best choice. Therefore, the higher refractive index MoS is used in this application2Instead of the material of the conventional high refractive index layer.
Based on formula (1), the present application employs MoS2As a material of the high refractive index layer, red may be madeThe reflectivity in the pass band of the outer band pass filter decreases, i.e. the transmittance increases. Moreover, simulation experiments prove that MoS is adopted in the application2As a material of the high refractive index layer, the shift amount of the center wavelength of the infrared band pass filter with respect to the angle can also be reduced. Thus, MoS2The material as the high refractive index layer is effective in improving the performance of the infrared band pass filter.
In addition, due to MoS2The layer can be formed by a thermal evaporation process, and thus, MoS is used2The material used as the material of the high-refractive-index layer in the filter stack of the infrared band-pass filter can lower the manufacturing complexity of the filter stack and lower the cost of the infrared band-pass filter. And, when SiO is used2When the material is used as the material with low refractive index, the material is formed by SiO2The high refractive index layer and the low refractive index layer can be formed by the same process, so that the manufacturing time is saved, the cost is reduced, and the mass production is easier. While for other materials used as high index layers, such as Si: H, it can only be formed by a sputtering process, i.e. in hydrogen (H)2) The deposition is carried out in the atmosphere by a sputtering mode, the refractive index and extinction coefficient of Si: H are related to the flow rate of hydrogen gas flow during sputtering, and the process mode has higher cost.
As can be seen from equation (1), increasing the difference between the refractive indices of the high refractive index layer and the low refractive index layer of the filter stack can improve the performance of the filter, and then in addition to increasing the refractive index of the high refractive index layer, the refractive index of the low refractive index layer can be decreased. Another benefit of reducing the refractive index of the low index layer is that the value of L in equation (1), i.e., the refractive index of the outermost film, can be reduced simultaneously, further reducing the thickness of the filter stack, thereby reducing RAVE. But is typically SiO due to the low refractive index materials used in current filter solutions2Refractive index n oflApproximately 1.46, while the refractive indices of the usual low-refractive-index layers are also all greater than 1.2, SiO2And the refractive index difference between the lowest refractive index material, and MoS2Small in comparison with the difference in refractive index between Si and H (about 0.7)Many are available. Thus replacing the material of the low index layer does not improve the filter performance as well as using MoS2Replacing the material of the high refractive index layer.
Another consideration is to replace the materials of both the high index layer and the low index layer to achieve a larger index difference. In this case, it is important to consider whether the deposition methods of the two materials with high refractive index and low refractive index are compatible, the bonding force is sufficient, and the Thermal Expansion Coefficients (CTE) are matched, so that the realization difficulty is high.
In view of this, in the embodiments of the present application, it is hard to find a material capable of being used as a high refractive index layer, and thus to find a high refractive index material MoS2As a material for the high refractive index layer. MoS2Layer with conventional SiO2Between the layers with low refractive indexes, the large refractive index difference is met, the compatibility of deposition modes is guaranteed, and the high-performance high-temperature-resistant optical film has good binding force and stability.
In the infrared bandpass filter 400 according to the embodiment of the present application, when the incident light angle changes, the shift of the center wavelength of the passband is small. For example, for a filter of the type shown in FIG. 2, MoS is used when the angle of incidence varies between 0 and 302The shift of the center wavelength of the pass band of the infrared band-pass filter 400 in which the layer is a high refractive index layer can be less than 10 nm; as another example, for a filter of the type shown in FIG. 1, MoS is used when the angle of incidence varies between 0 and 302The infrared band-pass filter 400 in which the layer is a high refractive index layer can have a shift of the center wavelength of the pass band of less than 30 nm.
The infrared band-pass filter 400 in the embodiment of the application has a high transmittance in the pass band, and the transmittance can reach more than 90%, so that the use requirement of a common infrared band-pass filter is met. In particular, under some designs, MoS is employed2The infrared band pass filter 400 having a high refractive index layer can have a transmission band of 99% or more.
The infrared band-pass filter 400 of the embodiment of the application has a large OD value in the stop band, wherein the OD value of the visible light band in the stop band can reach the OD valueAnd the OD value of the infrared band of the stop band can reach more than 2 when the OD value is more than 3 or more than 4, so that the use requirement of a common infrared band-pass filter is met. In particular, under some designs, MoS is employed2The OD value of the visible light band of the stop band of the infrared band-pass filter 400, in which the layer is a high refractive index layer, may be up to 39 or more, and the OD value of the infrared band of the stop band may be up to 2.2 or more.
The following describes in detail the filter stack 420 of the infrared band pass filter 400 of the embodiment of the present application as MoS with reference to fig. 6 to 112/SiO2Two possible structures of the same and the existing structure comprising Si: H/SiO2The performance of the infrared bandpass filters of the filter stacks were compared.
In one implementation manner, an embodiment of the present application provides a method based on MoS2/SiO2The infrared band-pass filter 400 of (1), the filter stacks 420 of the infrared band-pass filter 400 being disposed on both sides of a substrate 410, the filter stacks 420 forming a high-pass filter portion and a low-pass filter portion, respectively, in portions located on both sides of the substrate 410, the pass band of the infrared band-pass filter 400 being an overlapping portion of the pass band of the high-pass filter portion and the pass band of the low-pass filter portion.
For example, as shown in FIGS. 6 and 7, wherein FIG. 6 is based on Si: H/SiO2The filter stack of the filter is Si, H and SiO2As materials for the high refractive index layer and the low refractive index layer, respectively; FIG. 7 shows a MoS-based2/SiO2The filter stack of the filter is MoS2And SiO2As the material of the high refractive index layer and the low refractive index layer, respectively. FIG. 6 shows the Si-based H/SiO at incidence angles of 0 and 302Fig. 7 shows MoS-based transmittance curves at incident angles of 0 ° and 30 °2/SiO2The transmittance curve of the filter of (1).
The filters shown in fig. 6 and 7 include a substrate and filter stacks formed on both sides of the substrate, and both filters have passbands with center wavelengths of about 940 nm. The MoS-based device shown in FIG. 7 designed in the embodiment of the application2/SiO2The high pass filter portion of the filter of (a) comprises a plurality of MoS2The total number of layers and the plurality of low refractive index layers is 47 layers and the total thickness is 4.5um, and the low pass filter section includes a plurality of MoS2The total number of layers and the plurality of low refractive index layers was 23 layers and the total thickness was 4.9 um.
As can be seen from FIGS. 6 and 7, based on MoS2/SiO2The transmittance of the filter in the target wavelength band is higher and both the rising and falling edges are steeper than those of the Si: H based filter, so that the filter is less affected by ambient light. The second table shows the results based on Si: H/SiO2And based on MoS2/SiO2Table two shows the incidence Angle (included Angle) and the minimum wavelength (λ) in this orderminOr λL) Maximum wavelength (λ)maxOr λH) The passband filter includes, but is not limited to, a Center wavelength (Center λ), a Center wavelength Shift (Center Shift), a Full Width at Half Maximum (FWHM), a Maximum transmittance of the passband (Max Trans.), an average transmittance of the passband (avg. Trans.), and a slope amount of rising and falling edges of the passband (slope).
Based on Si H/SiO2The amount of shift of the center frequency wavelength of the filter of (1) at incident angles of 0 ° and 30 ° is 14 nm; based on MoS2/SiO2The amount of shift of the center wavelength of the optical filter of (1) is less than 10nm at the incidence angles of 0 ° and 30 °, wherein the amount of shift of the center wavelength of the optical filter designed when a shift of 10nm is targeted is only 8.8nm, and the amount of shift of the center wavelength of the optical filter designed when a shift of 5nm is targeted is only 7.2 nm. At the same time, based on MoS2/SiO2Based on the average transmittance ratio of Si to H/SiO in the FWHM pass band2The filter of (1) has an average transmission in the FWHM passband of about 6% higher and is based on MoS2/SiO2The maximum transmittance in the pass band of the filter is more than 99 percent compared with that based on Si: H/SiO2The transmittance of the optical filter is obviously improved. And is based on MoS2/SiO2The thickness of the filter stack of the filter is 1uBetween m and 10um, without a significant increase in the thickness of the filter stack.
Watch two
Figure 124580DEST_PATH_IMAGE003
As can be seen, the optical filter in this embodiment employs MoS2The layer is used as a high-refractive-index layer, and the performance of the layer is remarkably improved, particularly the offset of the central wavelength and the transmittance of a passband are remarkably improved.
In another implementation manner, an embodiment of the present application provides a method for implementing a MoS-based device2/SiO2The filter stack 420 of the infrared band pass filter 400 is disposed on one side of the substrate 410.
Further, optionally, the infrared band pass filter 400 may further include a light absorbing coating 430, and the light absorbing coating 430 is disposed on the other side of the substrate 410 for blocking light within a band of a stop band of the infrared band pass filter 400.
For example, FIG. 8 shows the results of the measurement of Si-based H/SiO at incidence angles of 0 and 30, respectively2The filter stack of the filter is Si, H and SiO2As materials for the high refractive index layer and the low refractive index layer, respectively; FIG. 9 shows MoS-based images at incidence angles of 0 and 302/SiO2The filter stack of the filter is MoS2And SiO2As materials for the high refractive index layer and the low refractive index layer, respectively; FIG. 10 is an enlarged view of the filter of FIG. 9 at the pass band; fig. 11 is an enlarged view of the filter of fig. 9 at the stop band.
The optical filters shown in fig. 8 to 11 include a substrate and a filter stack formed on one side of the upper surface or the lower surface of the substrate, and the central wavelengths of the pass bands of both the optical filters shown in fig. 8 and 9 are about 1550 nm. In the embodiment of the present application, the MoS-based devices shown in fig. 9 to 11 are designed2/SiO2Of the optical filterA MoS2The total number of layers and the plurality of low refractive index layers was 47 layers and the total thickness was 7.2 um.
As can be seen from FIGS. 8 and 9, based on Si: H/SiO2The filter has a stop band transmission of less than 0.5% in the visible and less than 2% in the infrared, based on MoS2/SiO2The transmittance of the stop band of the filter is close to 0% in the visible band and less than 0.7% in the infrared band. The third table shows that the catalyst is based on Si: H/SiO2And based on MoS2/SiO2Table three shows the incidence Angle (incorporated Angle), the minimum wavelength (λ) in that orderminOr λL) Maximum wavelength (λ)maxOr λH) Center wavelength (Center λ), Center wavelength Shift (Center Shift), FWHM, OD value (VIS OD) of the visible light band of the stop band, and OD value (IR OD) of the infrared light band of the stop band.
Based on MoS2/SiO2The amount of shift of the center frequency wavelength of the filter of (1) at incident angles of 0 ° and 30 ° is 35 nm; based on MoS2/SiO2The amount of shift of the center wavelength of the filter of (1) is less than 30nm at the incidence angles of 0 ° and 30 °, and the amount of shift of the center wavelength of the filter designed to target a shift of 25nm is only 27 nm. Meanwhile, as can be seen from table three, based on MoS2/SiO2The OD value of the stop band of the filter is obviously larger than that of the filter based on Si, H/SiO2The OD value of the stop band of the filter is based on MoS2/SiO2The OD value of the infrared band of the stop band of the filter is obviously larger than that based on Si, H/SiO2OD value of the stop band of the filter of (1). It can be seen that the MoS is based on2/SiO2The filter has better blocking (absorption and/or reflection) effect on light in the stop band, and the transmission of light in non-target wave bands is blocked to the maximum extent. Meanwhile, as can be seen from fig. 10, MoS-based2/SiO2The transmittance of the passband of the optical filter is more than 99 percent, and the optical filter has better transmittance for the light of a target wave band; as can be seen from FIG. 11, based on MoS2/SiO2The transmittance of the visible light wave band of the stop band of the filter is close to 0, and the transmittance of the infrared light wave band of the stop band is less than 0.7%, so that the filter can better block the light of the non-target wave band. And, based on MoS2/SiO2The thickness of the filter stack of the filter of (1) is less than 10um without a significant increase in the thickness of the filter stack.
Watch III
Figure 947042DEST_PATH_IMAGE004
As can be seen, MoS is used in this example2The layer is used as a filter of the high-refractive-index layer, and the performance of the layer is remarkably improved, particularly the offset of the central wavelength and the OD value of a stop band.
The two types of infrared bandpass filter designs described above are merely examples, and all use MoS2The layer as a filter for the high refractive index layer should fall within the scope of the present application.
In summary, the design of the infrared band pass filter of the present application reduces the shift of the center wavelength caused by the incident angle, and does not increase the thickness of the filter stack of the infrared band pass filter. In some implementations, the infrared bandpass filter has a reduced width of the leading and trailing edges of the passband and an increased transmittance for the target band. In other implementations, the infrared band-pass filter also increases the OD of the visible and infrared bands within the stop band.
The present application further provides a sensor system including the sensor system 1100 shown in fig. 12. The sensor system 1100 may be applied in distance detection, three-dimensional detection based on TOF, or optical communication.
As shown in fig. 12, the sensor system 1100 includes:
a light source 1110 for emitting light;
the infrared band-pass filter 400 of any of the above embodiments, configured to transmit a portion of the light emitted by the light source, which is located within a pass band of the infrared band-pass filter 400; and the number of the first and second groups,
sensor 1120 is used to detect the light transmitted by infrared band pass filter 400.
The sensor system 1100 may be, for example, a distance sensor system for acquiring a distance to a target; also for example, may be a TOF or structured light based three-dimensional imaging system for acquiring three-dimensional images of the target; for another example, in optical communication, light of a target wavelength band for optical communication may be selected, and light of a non-target wavelength band may be blocked.
It should be noted that, without conflict, the embodiments and/or technical features in the embodiments described in the present application may be arbitrarily combined with each other, and the technical solutions obtained after the combination also fall within the protection scope of the present application.
The system, apparatus and method disclosed in the embodiments of the present application can be implemented in other ways. For example, some features of the method embodiments described above may be omitted or not performed. The above-described device embodiments are merely illustrative, the division of the unit is only one logical functional division, and there may be other divisions when the actual implementation is performed, and a plurality of units or components may be combined or may be integrated into another system. In addition, the coupling between the units or the coupling between the components may be direct coupling or indirect coupling, and the coupling includes electrical, mechanical or other connections.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes and the generated technical effects of the above-described apparatuses and devices may refer to the corresponding processes and technical effects in the foregoing method embodiments, and are not described herein again.
It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application, and that various modifications and variations can be made by those skilled in the art based on the above embodiments and fall within the scope of the present application.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (22)

1. An infrared bandpass filter, comprising:
a substrate; and the number of the first and second groups,
a filter stack disposed on at least one side of the substrate, wherein the filter stack includes a plurality of MoS alternately stacked2A layer and a plurality of low refractive index layers having a refractive index less than the MoS2The refractive index of the layer;
the transmittance of the passband of the infrared band-pass filter is greater than 90%, the optical density OD of the visible light band of the stopband of the infrared band-pass filter is greater than 3, and the OD of the infrared band of the stopband of the infrared band-pass filter is greater than 2.
2. The infrared bandpass filter of claim 1 wherein the passband of the infrared bandpass filter at least partially overlaps with a wavelength range of 800nm to 2000 nm.
3. The infrared bandpass filter of claim 1 or 2, wherein the MoS is a filter with a band gap between the filter and the substrate2The refractive index of the layer is between 3.5 and 5.
4. The infrared bandpass filter of claim 1 or 2, wherein the MoS is a filter with a band gap between the filter and the substrate2Extinction coefficient of the layer being less than 5 x 10-3。
5. The infrared bandpass filter of claim 1 or 2, wherein the MoS is a filter with a band gap between the filter and the substrate2The layers are formed by evaporation.
6. The infrared bandpass filter of claim 1 or 2, wherein the low refractive index layer is composed of one or more of the following materials:
silicon dioxide SiO2Magnesium fluoride MgF, aluminum fluoride AlF, titanium dioxide TiO2Aluminum oxide Al2O3Niobium pentoxide Nb2O5Ta, tantalum pentoxide2O5。
7. The infrared bandpass filter of claim 1 or 2 wherein the low refractive index layer has a refractive index of less than 2.5.
8. The infrared bandpass filter according to claim 1 or 2, characterized in that the filter stack is provided on the upper surface side or the lower surface side of the substrate.
9. The infrared bandpass filter of claim 8, wherein the plurality of MoS' s2The total number of layers and the plurality of low refractive index layers is 47 layers and the total thickness is 7.2 um.
10. The infrared bandpass filter of claim 9 wherein the wavelength of the passband of the infrared bandpass filter comprises 1550 nm.
11. The infrared bandpass filter of claim 9 wherein the central wavelength of the passband of the infrared bandpass filter shifts by less than 30nm when the angle of incidence of the light rays varies between 0 ° and 30 °.
12. The infrared band-pass filter according to claim 9, characterized in that the optical density OD of the stopband of the infrared band-pass filter is greater than 39 and the optical density OD of the stopband of the infrared band-pass filter is greater than 2.2.
13. The infrared bandpass filter of claim 9 wherein the infrared bandpass filter has a passband with a transmittance greater than 99%.
14. The infrared bandpass filter of claim 8, wherein the infrared bandpass filter further comprises:
and the light absorption coating is arranged on the other side of the substrate and used for blocking light rays in a waveband of a stop band of the infrared band-pass filter.
15. The infrared band-pass filter according to claim 1 or 2, characterized in that said filter stacks are arranged on both sides of said substrate, said filter stacks forming a high-pass filter portion and a low-pass filter portion, respectively, in portions located on both sides of said substrate, the pass-band of said filter being the overlapping portion of the pass-band of said high-pass filter portion and the pass-band of said low-pass filter portion.
16. The infrared bandpass filter of claim 15,
the plurality of MoSs included in the high-pass filter section2The total number of layers and the plurality of low refractive index layers is 47 and the total thickness is 4.5 um;
the plurality of MoSs included in the low-pass filter section2The total number of layers and the plurality of low refractive index layers is 23 layers and the total thickness is 4.9 um.
17. The infrared bandpass filter of claim 16 wherein the wavelength of the passband of the infrared bandpass filter comprises 940 nm.
18. The infrared bandpass filter of claim 16 wherein the central wavelength of the passband of the infrared bandpass filter shifts by less than 10nm when the angle of incidence of the light rays varies between 0 ° and 30 °.
19. The infrared bandpass filter of claim 16 wherein the infrared bandpass filter has a passband with a transmittance greater than 99%.
20. The infrared band-pass filter according to claim 1 or 2, characterized in that it is applied in three-dimensional detection based on time-of-flight TOF or structured light, or in optical communication.
21. A sensor system, comprising:
a light source for emitting light;
the infrared bandpass filter of any one of claims 1 to 20, for transmitting a portion of the light rays emitted by the light source that is within the passband of the infrared bandpass filter; and the number of the first and second groups,
and the sensor is used for detecting the light transmitted by the infrared band-pass filter.
22. Sensor system according to claim 21, characterized in that the sensor system is applied in three-dimensional detection based on time-of-flight TOF or structured light, or in optical communication.
CN202010825667.0A 2020-08-17 2020-08-17 Infrared bandpass filter and sensor system Active CN111736249B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010825667.0A CN111736249B (en) 2020-08-17 2020-08-17 Infrared bandpass filter and sensor system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010825667.0A CN111736249B (en) 2020-08-17 2020-08-17 Infrared bandpass filter and sensor system

Publications (2)

Publication Number Publication Date
CN111736249A CN111736249A (en) 2020-10-02
CN111736249B true CN111736249B (en) 2020-11-17

Family

ID=72658479

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010825667.0A Active CN111736249B (en) 2020-08-17 2020-08-17 Infrared bandpass filter and sensor system

Country Status (1)

Country Link
CN (1) CN111736249B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220206201A1 (en) * 2020-12-25 2022-06-30 AGC Inc. Optical filter
CN115184956B (en) * 2022-09-09 2023-01-13 荣耀终端有限公司 TOF sensor system and electronic device

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7554736B2 (en) * 2004-04-02 2009-06-30 Konica Minolta Opto, Inc. Objective lens and optical pickup apparatus
JP2006153976A (en) * 2004-11-25 2006-06-15 Nippon Shinku Kogaku Kk Infra-red light transmission filter
US20110310472A1 (en) * 2009-02-13 2011-12-22 Takahiko Hirai Infrared optical filter and manufacturing method of the infrared optical filter
DE102011077983A1 (en) * 2011-06-22 2012-12-27 Carl Zeiss Smt Gmbh Method for producing a reflective optical element for EUV lithography
US10353124B1 (en) * 2015-10-16 2019-07-16 Board Of Trustees Of The University Of Alabama, For And On Behalf Of The University Of Alabama In Huntsville Omni-directional ultra-thin reflection optical filters and methods of fabrication
JP7326993B2 (en) * 2018-08-30 2023-08-16 Jsr株式会社 OPTICAL FILTER, MANUFACTURING METHOD THEREOF AND USE THEREOF

Also Published As

Publication number Publication date
CN111736249A (en) 2020-10-02

Similar Documents

Publication Publication Date Title
CN111736249B (en) Infrared bandpass filter and sensor system
JP7150464B2 (en) Mixed Metal/Dielectric Optical Filter
CN115586597A (en) Optical filter and sensor system
WO2020253535A1 (en) Optical filter with temperature compensation effect and sensor system
KR20220002320A (en) Near-infrared band-pass optical filter and optical sensing system
CN112444898B (en) Optical filter for wide-angle application
WO2019189039A1 (en) Optical filter
KR19980025055A (en) Light absorber and optical device using the same
TW201940450A (en) Optical device including stack of optical layers with functional treatment
WO2022036511A1 (en) Infrared bandpass optical filter and sensor system
CN115903112B (en) Optical filter
CA3031650C (en) Optical device having optical and mechanical properties
US20060018022A1 (en) CWDM filter with four channels
TWI549811B (en) Infrared filter
JP3917261B2 (en) Optical absorber and optical apparatus using the same
WO2020103206A1 (en) Polarization-independent filter
US20230296817A1 (en) Multi-transmission optical filter
JP2001100024A (en) Multilayered optical filter
KR102147373B1 (en) Infrared anti-reflection coating layer nd manufacturing method thereof
JP6228435B2 (en) Optical filter and manufacturing method thereof
CN103245999B (en) A kind of broad spectrum out-of-band rejection optical filter
CN113075758B (en) Infrared band-pass filter and sensor system
JP2017009704A (en) Optical element using multi-layer film, optical system and optical device
JP3894107B2 (en) Infrared antireflection film
CN115280194A (en) Interference filter, optical device and method for manufacturing interference filter

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant