Photoelectric sensor, optical device containing same, and light modulation method

Abstract

The present disclosure provides a photoelectric sensor, an optical device containing the same, and a light modulation method. The photoelectric sensor includes a super lens array and a sensing device, wherein the super lens array includes a plurality of super lenses, and each super lens includes a plurality of super pixel units. The sensing device includes a plurality of receiving units corresponding to the plurality of super pixel units, and each receiving unit includes a plurality of pixels. Each pixel is configured to convert a light signal of a specific band into an electrical signal. Each super pixel unit is configured to perform phase modulation on the incident light so that light of different bands is respectively transmitted to pixels matching the band in the receiving unit corresponding to the super pixel unit; the plurality of super pixel units include at least two super pixel units, and the at least two super pixel units have different phase distributions from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap. The present disclosure realizes color image sensing based on super lenses, which can improve energy utilization.

Description

Technical Field

[0001] The present disclosure relates to the technical field of photoelectric sensors, and in particular to a photoelectric sensor, an optical device including the same, and a light modulation method. Background Art

[0002] Conventional color image sensors primarily focus incident light through a microlens array, then separate the intensities of the different RGB color components (different wavelengths) through a Bayer filter. The color of the incident light is reconstructed based on the intensity received by the corresponding color sensors. For example, if the red, green, and blue light intensity is evenly distributed, each monochrome sensor receives only a maximum of one-third of the incident light energy. Furthermore, the Bayer filter itself is not fully transparent to monochromatic light, resulting in some loss. Therefore, the energy reaching the sensor is limited. Limited by the sensitivity of the imaging element, color image reconstruction presents certain challenges.

[0003] Prior art has proposed a solution that combines a metalens with color pixels. However, this solution requires the metalens to modulate three wavelengths simultaneously, with two focal points required for one of these wavelengths. This splitting scheme complicates the design of the metalens and results in weak response to incident light at wide angles. Consequently, the actual light energy utilization efficiency achieved by this solution falls far short of the theoretically predicted value. Summary of the Invention

[0004] To solve the above problems, the first aspect of the present application provides a photoelectric sensor, which includes a metalens array and a sensing device;

[0005] The super lens array includes a plurality of super lenses, each of the plurality of super lenses includes a plurality of super pixel units;

[0006] The sensing device includes a plurality of receiving units arranged in a one-to-one correspondence with the plurality of superpixel units, each of the plurality of receiving units includes a plurality of pixels, and each of the plurality of pixels is configured to convert an optical signal of a specific wavelength band into an electrical signal;

[0007] Each superpixel unit is configured to phase modulate the incident light so that light of different bands is respectively transmitted to pixels matching the bands in the receiving unit corresponding to the superpixel unit; the multiple superpixel units include at least two superpixel units, and the at least two superpixel units have different phase distributions from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0008] A second aspect of the present application provides an optical device, characterized in that the optical device includes an optical system and a photoelectric sensor provided according to any one of the above embodiments;

[0009] The photoelectric sensor is located in the image plane of the optical system.

[0010] A third aspect of the present application provides a light modulation method, applicable to the photoelectric sensor provided according to any of the above embodiments, comprising:

[0011] Providing a plurality of metalenses arranged in an array, and dividing each of the plurality of metalenses into a plurality of superpixel units;

[0012] A plurality of receiving units are provided in one-to-one correspondence with the plurality of super pixel units; each of the plurality of receiving units includes a plurality of pixels; each of the plurality of pixels is configured to convert an optical signal of a specific wavelength band into an electrical signal;

[0013] Each superpixel unit phase modulates the incident light so that light of different wavelengths is transmitted to the pixels matching the wavelengths in the receiving unit corresponding to the superpixel unit.

[0014] The phase distribution of multiple superpixel units is designed differentially, so that the multiple superpixel units include at least two superpixel units, and the phase distributions of at least two superpixel units are different from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0015] The technical solutions provided in the embodiments of the present application have achieved at least the following beneficial effects:

[0016] The solution provided in the embodiments of the present application uses a metalens to directly deflect light of different bands to pixels receiving different bands, thereby avoiding the problem of light energy loss caused by filters and improving energy utilization. Furthermore, the metalens is a sub-wavelength optical element that is suitable for current micron-scale sensor architectures. At the same time, its preparation process is compatible with mature semiconductor sensor technology, and has strong practicality and mass production potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of the overall structure of a photoelectric sensor provided by an embodiment of the present disclosure;

[0019] Figure 2 A schematic diagram of the working principle of a photoelectric sensor provided by an embodiment of the present disclosure;

[0020] Figure 3A planar arrangement of multiple sub-pixels of a photosensor provided in an embodiment of the present disclosure;

[0021] Figure 4 A schematic diagram of a three-dimensional structure of a super unit of a photoelectric sensor provided by an embodiment of the present disclosure;

[0022] Figure 5 A schematic diagram of the working principle of a photoelectric sensor provided by an embodiment of the present disclosure;

[0023] Figure 6 A planar arrangement of multiple sub-pixels of a photosensor provided in an embodiment of the present disclosure;

[0024] Figure 7 A planar arrangement of multiple sub-pixels of a photosensor provided in an embodiment of the present disclosure;

[0025] Figure 8 A schematic diagram of a super unit structure and detection form of a photoelectric sensor provided by an embodiment of the present disclosure;

[0026] Figure 9 A schematic diagram of a light path provided in an embodiment of the present disclosure;

[0027] Figure 10 A schematic diagram of a light path provided in an embodiment of the present disclosure;

[0028] Figure 11 A schematic diagram of a light path provided in an embodiment of the present disclosure;

[0029] Figure 12 The theoretical phase distribution for wavelengths of 700 nm and 546 nm in a set of structures for red light and green light detection provided in the first embodiment of the present disclosure;

[0030] Figure 13 The phase matching condition of the nanostructure on the y=0 section provided in the first embodiment of the present disclosure;

[0031] Figure 14 The theoretical phase distribution for wavelengths of 546 nm and 436 nm in a set of structures for green light and blue light detection provided in the first embodiment of the present disclosure;

[0032] Figure 15 The phase matching condition of the nanostructure on the y=0 section provided in the first embodiment of the present disclosure;

[0033] Figure 16 The normalized intensity distribution of the sensor plane under irradiation with 700nm, 546nm and 436nm monochromatic light provided in the first embodiment of the present disclosure;

[0034] Figure 17The normalized light intensity distribution of white light irradiation when the sub-pixel size is 3 μm provided in the second embodiment of the present disclosure;

[0035] Figure 18 The normalized light intensity distribution of white light irradiation when the sub-pixel sizes provided in the second embodiment of the present disclosure are 2.2 μm and 0.85 μm respectively.

[0036] List of reference numerals:

[0037] 10-super lens, 101-super pixel unit, 102-first super pixel unit, 103-second super pixel unit, 11-nanostructure, 12-substrate, 20-sensing device, 201-receiving unit, 202-first receiving unit, 203-second receiving unit, 204-third receiving unit, 205-fourth receiving unit, 21-pixel, 22-filter, 23-sub-pixel, 211-first pixel, 212-second pixel, 213-third pixel, 214-fourth pixel, 216-sixth pixel, 217-seventh pixel, 218-eighth pixel, 219-ninth pixel, 01-color Color pixel, 221-first filter, 222-second filter, 223-third filter, 224-fourth filter, 226-sixth filter, 227-seventh filter, 228-eighth filter, 229-ninth filter, 231-first sub-pixel, 232-second sub-pixel, 233-third sub-pixel, 234-fourth sub-pixel, 236-sixth sub-pixel, 237-seventh sub-pixel, 238-eighth sub-pixel, 239-ninth sub-pixel, 60-incident light, 606-band A light, 607-band B light, 608-band C light, 609-band D light. DETAILED DESCRIPTION

[0038] The present application will now be described more fully below with reference to the accompanying drawings, in which various embodiments are shown. However, the present application can be implemented in many different ways and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application will be exhaustive and complete and will fully convey the scope of the present application to those skilled in the art. Throughout, the same reference numerals represent the same components. Furthermore, in the drawings, the thicknesses, ratios, and sizes of the components are exaggerated for clarity of illustration.

[0039] The terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, as used herein, "a," "an," "the," and "at least one" do not represent a limitation on quantity, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, "a component" has the same meaning as "at least one component." "At least one" should not be interpreted as being limited to the quantity "one." "Or" means "and / or." The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meanings as in the relevant technical context, and unless explicitly defined in the specification, these terms are not interpreted as having formal meanings in an idealized or overly formal sense.

[0041] The meaning of “include” or “comprising” specifies properties, quantities, steps, operations, components, parts or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts or a combination thereof.

[0042] Embodiments are described herein with reference to cross-sectional views that are idealized embodiments. Thus, variations in shape relative to the illustrated embodiments are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions as shown herein, but rather should include deviations in shape that result from, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Furthermore, sharp angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0043] Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.

[0044] Traditional spectroscopic sensors disperse the light intensity during spectrometry. Taking the case of evenly distributed RGB light intensity as an example, each monochrome sensor receives only 1 / 3 of the incident light energy at most. In addition, the filter itself cannot completely transmit monochromatic light. The energy reaching the sensor is limited, making color image reconstruction difficult.

[0045] The prior art proposes a solution that encapsulates a metalens with a color pixel, and distributes visible light of different frequencies to different areas (at least four areas) on the color pixel through the metalens, omitting the role of the filter. However, in this technical solution, the metalens modulates light of three bands at the same time, and two focal points need to be modulated for one of the bands (green light). This light splitting solution increases the difficulty of designing the metalens, makes the selection of nanostructures difficult, and the deflection angle of the incident light at the diagonal position of the color pixel is too large. The photoelectric sensor does not respond strongly to light incident at large angles, resulting in the actual light energy utilization efficiency achieved by this solution being only 25% to 40%, far from the theoretical value of light energy utilization (100%) that it is expected to achieve. On the other hand, the size of the color pixel is usually in the micron order. When the micron-scale metalens modulates light of three bands at the same time, the characteristic size of the nanostructure is small, and the process requirements are extremely high.

[0046] In view of this, the present application proposes a photoelectric sensor that can be used to realize color image sensing, infrared thermal imaging, and multi-band imaging that combines color and infrared.

[0047] See also Figure 1 , an embodiment of the present invention provides a photoelectric sensor, including a super lens array. The super lens array includes a plurality of super lenses 10, and each super lens 10 includes a plurality of super pixel units 101. The photoelectric sensor also includes a sensing device 20. The sensing device 20 includes a plurality of receiving units 201 arranged in a one-to-one correspondence with the super pixel units 101. Each receiving unit 201 includes a plurality of pixels 21. Each pixel 21 receives a light signal of a specific band and responds to the light signal of a specific band. Each pixel 21 is configured to convert the light signal of a specific band into an electrical signal. Each super pixel unit 101 is configured to phase modulate the incident light 60 so that light of different bands is respectively transmitted to pixels matching the band in the receiving unit corresponding to the super pixel unit. The plurality of super pixel units 101 include at least two super pixel units, and the at least two super pixel units have different phase distributions from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0048] In one embodiment, for any super pixel unit 101, light of some wavelengths among the light of different wavelengths passing therethrough is respectively transmitted to corresponding pixels and converted into electrical signals, for example Figure 2 As shown, after the incident light 60 passes through the first super pixel unit 102, only part of the wavelengths of red light (R), green light (G) and blue light (B) (R and G) are transmitted to the first pixel 211 (configured to respond to red light) and the second pixel 212 (configured to respond to green light) in the first receiving unit 202 corresponding to the first super pixel unit 102, and then converted into electrical signals; for example Figure 5As shown, after the incident light 60 passes through the first superpixel unit 102, only two of the four wavelength bands are transmitted to the sixth pixel 216 (configured to respond to light from one of the two wavelength bands) and the seventh pixel 217 (configured to respond to light from the other of the two wavelength bands) in the third receiving unit 204 corresponding to the first superpixel unit 102, and then converted into electrical signals. It can be understood that after M wavelength bands of light pass through a superpixel unit, N wavelength bands of light are transmitted to pixels matching the wavelength bands in the pixel unit corresponding to the superpixel unit, and then converted into electrical signals, where M>N≥2. Optionally, the multiple superpixel units 101 include superpixel unit A and superpixel unit B. After the light of M1 band passes through superpixel unit A, the light of N1 band is respectively transmitted to the pixels matching the band in the A receiving unit corresponding to superpixel unit A and then converted into electrical signals. After the light of M2 band passes through superpixel unit B, the light of N2 band is respectively transmitted to the pixels matching the band in the B receiving unit corresponding to superpixel unit B and then converted into electrical signals. Preferably, superpixel unit A 102 and superpixel unit A 103 are arranged adjacent to each other. Optionally, M1=M2, N1≠N2. Optionally, M1≠M2, N1=N2. Optionally, M1≠M2, N1≠N2. Optionally, any two adjacent superpixel units in the multiple superpixel units 101 are superpixel unit A and superpixel unit B, respectively.

[0049] It should also be noted that if any super-pixel unit and the corresponding receiving unit are regarded as a super-unit, light is only transmitted in the super-unit, that is, light is transmitted from the super-pixel unit in the super-unit to the receiving unit in the super-unit, and will not be deflected and transmitted to the receiving unit in the adjacent super-unit. In other words, each super-pixel unit is configured so that after light passes through it, the light will only be transmitted to the receiving unit corresponding to the super-pixel unit. For example Figure 2 As shown, after the incident light 60 passes through the first super pixel unit 102 , the light will only be transmitted to the first receiving unit 202 corresponding to the first super pixel unit 102 , and will not be transmitted to the adjacent second receiving unit 203 .

[0050] By designing the phase distribution of the super pixel unit, the super pixel unit has different responses to light of different wavelengths. In one embodiment, super pixel units with different modulation phases are arranged adjacent to each other. In one embodiment, the plurality of super pixel units include a first super pixel unit and a second super pixel unit with different phase distributions. Figure 2 The first super pixel unit 102 and the first super pixel unit 102 shown in the dotted box on the upper left Figure 2The second superpixel unit 103 is indicated by the dotted box in the upper right corner. Optionally, the first superpixel unit 102 is configured so that after light of different wavelengths passes through the first superpixel unit 102, red light and green light are respectively transmitted to the first pixel 211 responding to red light and the second pixel 212 responding to green light in the first receiving unit 202 corresponding to the first superpixel unit 102; the second superpixel unit 103 is configured so that after light of different wavelengths passes through the second superpixel unit 103, blue light and green light are respectively transmitted to the third pixel 213 responding to blue light and the fourth pixel 214 responding to green light in the second receiving unit 203 corresponding to the second superpixel unit 103. Because the red-green band and the blue-green band both involve the green band, the light bands transmitted to the corresponding pixels partially overlap. Optionally, the first superpixel unit 102 is configured so that after light of different wavelength bands passes through the first superpixel unit 102, red light and green light are modulated by the first superpixel unit 102 and transmitted respectively to the first pixel 211 responding to red light and the second pixel 212 responding to green light in the first receiving unit 202 corresponding to the first superpixel unit 102; and the second superpixel unit 103 is configured so that after light of different wavelength bands passes through the second superpixel unit 103, yellow light and blue light are modulated by the second superpixel unit 103 and transmitted respectively to the third pixel 213 responding to yellow light and the fourth pixel 214 responding to blue light in the second receiving unit 203 corresponding to the second superpixel unit 103. Because the red-green band and the yellow-blue band cover completely different wavelengths, the wavelengths of light transmitted to the corresponding pixels are different. Optionally, multiple superpixel units 101 are matched with multiple receiving units 201 in quantity, for example, 2 superpixel units are set corresponding to 2 receiving units; 4 superpixel units are set corresponding to 4 receiving units; 8 superpixel units are set corresponding to 8 receiving units, and so on.

[0051] In one embodiment, each superpixel unit 101 is configured to perform phase modulation on the incident light 60 so that light of some bands in different bands is converted into electrical signals by pixels of corresponding bands, and some bands include at least two bands.

[0052] In one embodiment, any two adjacent superpixel units among the plurality of superpixel units have different phase distributions from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0053] In one embodiment, any two adjacent pixels in a receiving unit 201 are configured to convert optical signals of different wavelength bands into electrical signals.

[0054] In one embodiment, in each receiving unit 201 , any two adjacent pixels are configured to convert optical signals of different wavelength bands into electrical signals.

[0055] In one embodiment, the optical bands received by any two adjacent receiving units 201 are different or partially overlapped.

[0056] In one embodiment, after the incident light 60 passes through the superpixel unit 101, any one of the light rays of different wavelength bands is mapped to any one or more of the multiple pixels 21.

[0057] In one embodiment, each pixel 21 includes a filter 22 and a sub-pixel 23 arranged in sequence along the optical path, the filter 22 is configured to transmit light of a specific wavelength band; the sub-pixel 23 responds to the light signal of the specific wavelength band and can receive the light signal of the specific wavelength band, and the sub-pixel 23 is configured to convert the light signal of the specific wavelength band into an electrical signal. The filter 22 and the sub-pixel 23 are arranged in a one-to-one correspondence. Optionally, the filter 22 and the sub-pixel 23 are arranged on the same optical axis. Optionally, the multiple receiving units 201 include at least two types of receiving units, and the at least two receiving units are different from each other in the number of pixels contained. Optionally, different types of receiving units containing different numbers of pixels are arranged adjacent to each other. Optionally, all receiving units 201 contain the same number of pixels 21.

[0058] In one embodiment, along the pixel arrangement, the filters 22 in two adjacent pixels are connected end-to-end, forming a seamless connection. This prevents light from leaking through the gaps between the filters and generating stray light signals that could affect detection. It should be noted that the filters 22 ensure that the specific wavelength bands received by the pixels are free of stray light, thus eliminating the corresponding electrical signals from interfering with detection. This improves energy efficiency while maintaining the signal-to-noise ratio.

[0059] In one embodiment, each metalens 10 includes a nanostructure 11 and a substrate 12. The nanostructure 11, substrate 12, and pixel 21 are sequentially arranged along the optical path. Optionally, the substrate 12 and pixel 21 are arranged adjacent to each other.

[0060] Figure 2 An example of a photoelectric sensor is shown. Figure 2 The dotted line in the middle is the boundary. Figure 2 The left part shows the first super pixel unit 102 and the first receiving unit 202 which are arranged corresponding to each other (the first super pixel unit 102 and the first receiving unit 202 are together regarded as the first super unit). Figure 2The right part shows the second super pixel unit 103 and the second receiving unit 203 which are arranged corresponding to each other (the second super pixel unit 103 and the second receiving unit 203 are regarded as the second super unit together). For example, when the first super pixel unit 102 is designed for phase modulation, only its modulation of the red band and the green band is considered, while its modulation of the blue band light is not considered. Specifically, after the incident light 60 passes through the first super pixel unit 102, it can be divided into three color components: red light (R), green light (G), and blue light (B). Among them, the red light is modulated by the first super pixel unit 102 and transmitted to the first pixel 211 in the first receiving unit 202 that responds to red light, and the green light is modulated by the first super pixel unit 102 and transmitted to the second pixel 212 in the first receiving unit 202 that responds to green light. Since the first filter 221 with a high transmittance only for red light is set upstream of the optical path of the first sub-pixel 231, only red light can reach the first sub-pixel 231. Thereby, the first pixel 211 receives the red light component in the light of different wavelengths transmitted from the first super pixel unit 102 and converts the red light component into a corresponding electrical signal. Since the second filter 222 with high transmittance only for green light is set upstream of the optical path of the second sub-pixel 232, only green light can reach the second sub-pixel 232. Thereby, the second pixel 212 receives the green light component in the light of different wavelengths passed through the first super pixel unit 102 and converts the green light component into a corresponding electrical signal. The blue light (B) may be deflected to a certain extent after passing through the first super pixel unit 102, but no matter whether it is deflected to the first pixel 211 or the second pixel 212, due to the existence of the first filter 221 and the second filter 222, it cannot be received by the first pixel 211 and the second pixel 212, so no electrical signal can be formed. Therefore, Figure 2 The supercell on the left side of the dotted line has no actual response to blue light. Figure 2 The image is shown as a direct irradiation but blocked by a filter.

[0061] therefore, Figure 2 The first super unit on the left side of the dotted line can make full use of the energy of red light and green light. For the second super unit on the right side of the dotted line, it is exemplarily configured to receive blue light (B) and green light (G), and has no response to red light (R). Similar to the first super unit on the left side of the dotted line, after modulation by the second super pixel unit 103, the third filter 223, and the fourth filter 224, the blue light is transmitted to the third sub-pixel and converted into an electrical signal, and the green light is transmitted to the fourth sub-pixel 234 and converted into an electrical signal, thereby achieving complete conversion of the blue light component and the green light component of the incident light 60 into electrical signals.

[0062] At the same time, the two super unit structures on the left and right sides are arranged in parallel front and back to form a color pixel 01, which can fully detect the color light signal with only 1 / 3 of the energy lost in theory, so that the theoretical upper limit of the light energy utilization rate of the sensor provided in the embodiment of the present application can reach 2 / 3, and the imaging clarity can be improved without additional improvement of the sensor sensitivity.

[0063] At the same time, Figure 2 For example, if the first supercell on the left lacks filters 221 and 222, it cannot filter the intensity of the corresponding blue light component. If the first supercell on the right lacks filters 223 and 224, it cannot filter the intensity of the corresponding red light component. If sub-pixel 23 receives complex light, it cannot convert the corresponding color components of the light into electrical signals.

[0064] According to the implementation mode of this application, Figure 2 As shown, the phase distribution of each super pixel unit 101 is configured not to deflect light toward adjacent super pixel units. In other words, the phase distribution of any super pixel unit 101 is such that the deflection of light is limited to the space defined by the super unit to which the super pixel unit 101 belongs. For example Figure 2 As shown, even though the second pixel 212 is adjacent to the third pixel 213 , they only receive light deflected by the superpixel unit in the superunit to which they belong.

[0065] In one embodiment, the photoelectric sensors are arranged in a regular quadrilateral. Figure 2 The two super units shown are arranged in parallel, so that four pixels form a regular quadrilateral color pixel 01. Repeated arrangement of color pixels 01 can construct a sensor device 20 of a certain area. The plane arrangement is as follows: Figure 3 shown.

[0066] like Figure 3 As shown, for example, in any regular quadrilateral color pixel 01, two green (G) pixels are set along one diagonal line of the regular quadrilateral, and red (R) pixels and blue (B) pixels are set along the other diagonal line. The three-dimensional design diagram of the receiving unit 201 with a group of R pixels and G pixels as an example is as follows: Figure 4 , basic principles and Figure 2 left Figure 1 As a result, the red light (R) is deflected to the first pixel 211 through the first super pixel unit 102, and the green light (G) is deflected to the second pixel 212.

[0067] In another embodiment, along the arrangement direction of the superpixel units, any two adjacent superpixel units have different phase distributions, so that the light bands transmitted to the corresponding pixels are different.

[0068] For example, taking the incident light 60 as an example, which is divided into four color components, two different wavelength bands of the incident light 60 are deflected as a group, and light energy outside the two wavelength bands is filtered out to achieve color sensing.

[0069] The specific principle is as follows Figure 5 As shown. The incident light 60 radiated to the metalens 10 can be divided into four components: band A, band B, band C and band D. Figure 5 The first super-element, located to the left of the dotted line, receives light 606 in band A and light 607 in band B, but has no actual response to radiation in bands C and D. Light 606 in band A is modulated by the first super-pixel unit 102 to be transmitted in a direction converging toward the sixth pixel 216, passing through the substrate 12 and reaching the sixth filter 226. The sixth filter 226 is configured to have a high transmittance only for light 606 in band A, allowing light 606 in band A to reach the sixth sub-pixel 236. The sixth pixel 216 responds to the component of light 606 in band A radiated onto the first super-element and converts it into a corresponding electrical signal. The light 607 in the B band is modulated by the first superpixel unit 102 to be transmitted in a direction converging toward the seventh pixel 217, passes through the substrate 12, and reaches the seventh filter 227, which has a high transmittance only for the light 607 in the B band. It is then detected by the seventh subpixel 237 and converted into an electrical signal corresponding to the component of the light 607 in the B band. After passing through the first superpixel unit 102, the light 608 in the C band and the light 609 in the D band cannot pass through either the sixth filter 226 or the seventh filter 227 to form an electrical signal. Therefore, Figure 5 The supercell on the left side of the dotted line will not actually respond to the radiation in the C-band and D-band.

[0070] Similarly, for Figure 5 The second super-unit on the right side of the middle dashed line is configured to receive light 608 in the C-band and light 609 in the D-band range, but has no actual response to radiation in the A-band and B-band ranges. Figure 5 The second super-unit on the right side of the middle dashed line can completely convert the light component 608 in the C band and the light component 609 in the D band of the incident light 60 radiated onto the second super-unit into electrical signals through the second super-pixel unit 103, the eighth filter 228, the ninth filter 229, the eighth sub-pixel 238, and the ninth sub-pixel 239. Figure 5 As shown, the two super units on the left and right sides of the dotted line are placed side by side to form a color pixel 01, which can fully detect the color light signal.

[0071] In one embodiment, the Figure 5The two groups of receiving units shown in the figure are repeatedly arranged on a plane to construct a sensing device 20 of a certain area. The arrangement of the two groups of receiving units on a plane is as follows: Figure 6 shown.

[0072] In one embodiment, the color pixels 01 are arranged in a regular hexagon. The regular hexagonal color pixel 01 includes seven sub-pixels, one of the seven sub-pixels is centered, and the remaining six sub-pixels are arranged around the central pixel.

[0073] For example, taking the incident light 60 as an example, the color components of the three parts RGB are arranged as follows: Figure 7 As shown, if any sub-pixel is located at the center of the hexagon, the six adjacent pixels are sub-pixels of different colors from the central pixel. Furthermore, sub-pixels of different colors are distributed alternately in a clockwise or counterclockwise direction around the central pixel.

[0074] In the embodiment and various optional embodiments of the present application, the provided metalens 10 is a metasurface, which is a layer of subwavelength artificial nanostructure film, and can modulate the amplitude, phase, and polarization of the incident light 60 through the nanostructures disposed thereon. It should be noted that the nanostructure can be understood as a subwavelength structure containing all-dielectric or plasmonic materials that can cause phase mutations, and the nanostructure is a structural unit centered on each nanostructure obtained by dividing the metalens 10. In the metalens 10, the nanostructures are periodically arranged on the substrate 12, wherein the nanostructures in each period constitute a superstructure unit, wherein the superstructure unit is a densely packed pattern, such as a regular quadrilateral, a regular hexagon, etc., each period contains a group of nanostructures, and the vertices and / or centers of the superstructure unit can be provided with nanostructures, for example.

[0075] For example, the nanostructures provided in the embodiments of the present application can be polarization-independent structures that impose a propagation phase on the incident light 60. Depending on the implementation of the present application, the nanostructures can be positive or negative. For example, the shapes of the nanostructures include cylinders, hollow cylinders, square prisms, hollow square prisms, and the like.

[0076] For example, the nanostructure can be a polarization-dependent structure that imposes a geometric phase on the incident light 60. The nanostructure can be a positive structure or a negative structure. For example, the nanostructure can be an elliptical column, a nanofin, or the like. According to an embodiment of the present application, the characteristic size of the nanostructure is greater than or equal to 0.2λ. c , and less than or equal to 0.8λ c ;λ c is the central wavelength of the incident light 60.

[0077] In the embodiments of the present application and various optional embodiments, since the metalens on the same group of structures only need to consider light of some bands among the light of different bands passing through the metalens, the difficulty of phase design and nanostructure matching is reduced, and the requirements for the phase change of the superpixel unit with the wavelength are reduced, and the use of structures with large phase changes with wavelength but difficult to process, such as cross columns, can be minimized.

[0078] In the present embodiment and various alternative embodiments, the operating wavelength band of the photosensor can be any one or more of the visible light band, the near infrared band, the mid-infrared band, and the far infrared band. For example, the sub-pixel provided in the present embodiment can be a bolometer that responds to incident radiation in the infrared band.

[0079] Typically, the wavelengths of the three primary colors of RGB are 700nm for red light (R), 546nm for green light (G), and 436nm for blue light (B). When designing wavelength modulation, the phase can be designed for the three wavelengths mentioned above. Taking into account the wavelength response range of the color filter, the phase of the super-pixel unit can be designed for the center wavelength first, and the phase can be fine-tuned within a narrow wavelength region. It is only necessary to deflect and converge the light of the selected wavelength band to a specific position when the phase changes with the wavelength. Therefore, in one embodiment, multiple pixels are configured to receive light in the 400-500nm band, light in the 500-600nm band, and light in the 600-750nm band, respectively, so that the sensor is designed based on the three primary colors of RGB.

[0080] Typically, the visible light band ranges from 400 to 760 nm. Therefore, in one embodiment, multiple sub-pixels are configured to receive light in the 400-500 nm band, the 500-580 nm band, the 580-630 nm band, and the 630-750 nm band, respectively, allowing the sensor to perform color imaging within the visible light range.

[0081] In one embodiment, multiple sub-pixels are configured to respectively receive light in the 400-500nm band, light in the 500-600nm band, light in the 600-750nm band, and light in the band above 750nm, so that the sensor can perform thermal imaging detection in the infrared range.

[0082] In each embodiment of the present application, the super lens 10 mainly converges light of different wavelengths. In one embodiment, its phase distribution is It can be expressed by the following formula:

[0083]

[0084]

[0085]

[0086] Wherein, i is the wavelength number for color differentiation, and in each embodiment of the present application, it can be set to i=1, 2, 3 or i=1, 2, 3, 4. i is the wavelength that needs to be modulated. (x,y) is the coordinate position of the surface of the nanostructure on the metalens, (x i ,y i ) is the wavelength λ i The light spot formed by the incident light on the photoelectric sensor is relative to the detection λ i The offset position of the center point of the photoelectric sensor, usually for a center-focused and centrally placed sensor, x i It is also half the sub-pixel width. C i 、A i and B i is the wavelength λ i The phase bias constant under , the main influencing factor in optical phase modulation is the phase gradient, the constant phase here does not affect the optical performance, but the phase of the nanostructure with wavelength change is limited, the reasonable selection of the phase bias constant can reduce the deviation generated in the nanostructure database matching process and improve the optical efficiency; p, n and m are the maximum order of the phase coefficient; for example, a i,k 、b i,s and c i,t The wavelengths λ i The phase coefficient of the next k-th, s-th, or t-th order.

[0087] f is the distance between the metalens 10 and the focal point. Since the metalens 10 needs to converge the light onto the sensor device 20 that is in close contact with the substrate 12, f is close to the sum of the thickness d1 of the substrate 12 and the thickness d2 of the filter, that is, f≈d1+d2. Moreover, the focal length is consistent at different wavelengths in a flat and compact device architecture. Taking the incident light of wavelength λ1 as an example, the device structure and detection form are shown in the figure below. Figure 8 As shown. Generally speaking, in order to save equipment space, the volume of optical elements and sensor elements is relatively small. Generally, the filter is directly attached to the sub-pixel 23 (or is directly processed on it). The super lens 10 can be directly stacked on the filter, and there may be only a small gap. In addition, formula (1) should in principle take into account the focal length offset caused by refraction at the interface between the substrate and the filter, but the light only needs to converge on the sub-pixel 23, and the photosensor has a certain area (width is L) and can detect a diffuse spot with a certain area, so the focal length here is still simply designed to be f≈d1+d2. For formulas (2) and (3), the phase coefficient can be reasonably designed to take into account the refraction at the interface between the substrate and the filter, so that the effective focal length of the super lens 10, substrate 12 and the filter as a whole is d1+d2.

[0088] For example, Figure 8 The case where the sub-pixel is rectangular is shown. In this case, the effective focal length f and the maximum refraction angle θ of the metalens 10 are max At least meet:

[0089]

[0090]

[0091] Wherein, L is the width of the photoelectric sensor; W is the width of any sub-pixel; d1 is the thickness of the substrate 12 along the optical axis; d2 is the thickness of the filter 22 along the optical axis. Satisfying conditional expressions (4) and (5) reduces the requirements of the photoelectric sensor provided by the embodiment of the present application on the ability of the metalens 10 to deflect light, reduces the difficulty of the phase design of the metalens 10, and the smaller incident angle is conducive to matching the effective incident angle of the sensor photoelectric conversion, thereby improving the conversion efficiency and imaging clarity. In order to ensure that the obliquely incident light at a certain angle can produce an effective response (that is, the energy of the obliquely incident light can be effectively collected), it is necessary to avoid the edge light from being offset and failing to radiate to the sensor, resulting in energy loss.

[0092] At the same time, if we consider the effective collection of energy from obliquely incident light, the smaller the sum of the substrate and filter thickness, the larger the sensor width, and the larger the supported incident angle. Taking a sensor with a pixel size of 1.75μm as an example, modulated for a wavelength of 635nm, Figure 9 The optical path diagram shows that the sum of the substrate thickness and the filter thickness is 4μm and the effective focal length is set to 4μm. The sensor can fully receive light with normal incidence (0°), 5°, and 10°, so the incident angle range is 0° to 10°. Figure 10 The diagram shows the light propagation path for a combined substrate and filter thickness of 10 μm and an effective focal length of 10 μm. At this point, a 10° incident light ray 60 deviates from the sensor it is intended to irradiate (and is subsequently blocked by the filter), resulting in a maximum detectable angle of incidence of approximately 5°. The effective focal length of the metalens 10 cannot be too small, otherwise the deflection angle will be too large. The selectable focal length range is 2 μm to 20 μm.

[0093] In addition, in each embodiment of the present application, the effective focal length should satisfy conditional expressions (4) and (5) so that the photoelectric sensor provided in the embodiment of the present application can support a larger incident angle and have a higher energy utilization rate. Figure 11When the combined thickness of the substrate and filter is 4μm, the focal length is set to 4.6μm. Light with normal incidence and an incident angle of 5° is received, but light with an incident angle of 10° will deviate from the sensor. Therefore, a typical design sets the effective focal length to the optical distance between the metalens 10 and the sub-pixel 23, which is approximately the combined thickness of the substrate 12 and the filter. To support light with incident angles of 20° or greater, further optimization of the modulation phase is required.

[0094] In each embodiment of the present application, for the same superpixel unit, it is necessary to consider its modulation of at least two different wavelength bands. Therefore, the phase distribution of the metalens 10 should satisfy two phase distributions under at least two wavelength bands, and it is necessary to fully utilize the changes in the phase response of the nanostructure 11 under different wavelengths. In matching nanostructures of different wavelengths at the same position, the nanostructure with the smallest phase deviation is generally selected, and the theoretical phase at wavelengths λ1 and λ2 at position (x0, y0) is λ1. and For example, the phase deviation should be minimum. The phase deviation between the theoretical phase and the actual phase satisfy:

[0095]

[0096] in, and is the phase of the same nanostructure in the nano database at wavelengths λ1 and λ2.

[0097] Since the main influencing factor in optical phase modulation is the phase gradient, the phase bias constant C i 、A i and B i It does not affect the optical performance, but the phase of the nanostructure 11 varies with wavelength, i.e. and The numerical variation of is limited (nonlinear variation), and it is necessary to reasonably select the phase bias constant to make full use of different structural units. and The changes in the nanostructure database can reduce the phase deviation generated during the matching process, thus improving the optical efficiency.

[0098] In various embodiments of the present application, the visible light band nanostructure 11 is generally made of silicon nitride or titanium dioxide, and the substrate 12 is made of silicon dioxide.

[0099] The photoelectric sensor involved in this application is described in more detail below using more specific application scenarios.

[0100] Example 1

[0101] A color image sensor is constructed using sub-pixels with a size of 1.75 μm. In this case, the width of a color pixel is 3.5 μm, the effective focal length of the super-lens 10 is set to 4 μm, and the sum of the thickness of the substrate and the thickness of the filter is 4 μm. The phase distribution of the super-pixel units in the two groups of structures in the color pixel can be calculated. Figure 12 The upper and lower figures in the figure are the theoretical phase distributions of the superpixel units in a set of structures for detecting red light (R) and green light (G) for wavelengths of 700nm and 546nm, respectively. Figure 13 The upper and lower figures in the figure are the phase matching of the nanostructure on the y=0 section respectively. From the phase change trend, it can be seen that the red light converges to the right and the green light converges to the left. Figure 14 The upper and lower figures in the figure are the theoretical phase distributions of the superpixel units in a set of structures for detecting green light (G) and blue light (B) for wavelengths of 546nm and 436nm, respectively. Figure 15 The upper and lower figures in the figure respectively reflect the phase matching of the nanostructure on the y=0 section line.

[0102] When red light (700nm), green light (546nm), and blue light (436nm) are used to illuminate the color detection pixel respectively, the sub-pixel corresponding to the color detection converts the received light signal into an electrical signal intensity, such as Figure 16 From left to right, the intensity of the R, G, and B monochrome detection sensors and the corresponding detected color components when illuminated by light of different wavelengths are shown. When used for color photography, the color is reconstructed based on the intensity of each wavelength in the incident light detected by the sensor and the color ratio of the backend.

[0103] Example 2

[0104] The main reason for the different resolutions of different camera devices is the different sizes of the sensors used. For the metalens 10 with a size of sub-wavelength order, it is only necessary to adjust the nanostructure period and reasonably design the arrangement to meet the imaging sensing requirements of sensors of different sizes. Figure 17 and Figure 18 Shown is the normalized light intensity distribution under white light illumination after sampling this scheme when the sub-pixel size is 3μm, 2.2μm and 0.85μm, where one color pixel has four parts, but it is still divided into RGB three colors.

[0105] In a second aspect, an embodiment of the present application further provides an optical device, which includes an optical system and a photoelectric sensor provided according to any of the above embodiments; the photoelectric sensor is located in the image plane of the optical system.

[0106] In a third aspect, the present application also provides a light modulation method applicable to the photoelectric sensor provided in any of the above embodiments. The method includes:

[0107] Providing a plurality of super lenses 10 arranged in an array, and dividing each of the plurality of super lenses 10 into a plurality of super pixel units 101;

[0108] Along the incident light path, a plurality of receiving units 201 are arranged in one-to-one correspondence with the plurality of super pixel units 101; each of the plurality of receiving units includes a plurality of pixels 21; each of the plurality of pixels is configured to convert an optical signal of a specific wavelength band into an electrical signal;

[0109] Each super pixel unit 101 performs phase modulation on the incident light 60 so that light of different wavelength bands is respectively transmitted to pixels matching the wavelength band in the receiving unit corresponding to the super pixel unit;

[0110] The phase distribution of multiple superpixel units 101 is designed differentially, so that the multiple superpixel units include at least two superpixel units, and the phase distributions of at least two superpixel units are different from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0111] Exemplarily, any two adjacent superpixel units among the plurality of superpixel units have different phase distributions from each other, so that the light bands transmitted to the corresponding pixels are different or partially overlap.

[0112] As another example, any two pixels in any two adjacent receiving units are configured to receive light bands that are different or partially overlap.

[0113] According to an embodiment of the present application, the metalens 10 includes multiple phase regions, and the nanostructures in the multiple phase regions are arranged to converge light of different wavelength bands to pixels matching the wavelength bands. Alternatively, the nanostructures in the multiple phase regions are arranged to converge light of portions of different wavelength bands to pixels matching the wavelength bands.

[0114] In the above-described embodiments and preferred embodiments, a metalens 10 is employed to individually control the deflection of light in different wavelength bands. Combined with filters, this enables color image sensing, improving energy efficiency and image clarity. Furthermore, the structural unit of the metalens 10 is widely applicable to sensors of varying microscale sizes, and its fabrication process is compatible with established semiconductor sensor technology, demonstrating its strong practicality and potential for mass production.

[0115] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solution that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A photoelectric sensor, characterized in that: The photoelectric sensor includes a super lens array and a sensing device (20); The super lens array includes a plurality of super lenses (10), each of the plurality of super lenses (10) includes a plurality of super pixel units (101); The sensing device (20) includes a plurality of receiving units (201) arranged in a one-to-one correspondence with the plurality of super pixel units (101), each of the plurality of receiving units (201) includes a plurality of pixels (21), each of the plurality of pixels (21) is configured to convert a light signal in a specific wavelength band into an electrical signal, and each of the plurality of pixels (21) includes a filter (22) and a sub-pixel (23) arranged in sequence along an optical path; Each superpixel unit (101) is configured to perform phase modulation on incident light (60) so that light of different wavelength bands is respectively transmitted to pixels matching the wavelength bands in a receiving unit corresponding to the superpixel unit; the multiple superpixel units (101) include at least two superpixel units, and the at least two superpixel units have different phase distributions from each other so that the wavelength bands of light transmitted to the corresponding pixels are different or partially overlap; Each of the plurality of super lenses comprises a nanostructure (11) and a substrate (12); the effective focal length of each super lens (10) in the plurality of super lenses is At least: ； is the width of the photosensor; W is the width of any one of the plurality of pixels (21); is the thickness of the substrate (12) along the optical axis; is the thickness of any one of the multiple filters (22) along the optical axis direction.

2. The photoelectric sensor according to claim 1, wherein: The filter (22) is configured to transmit light in the specific wavelength band; and the sub-pixel (23) is configured to convert the light signal in the specific wavelength band into an electrical signal.

3. The photoelectric sensor according to claim 1, wherein Any two adjacent superpixel units among the multiple superpixel units (101) have different phase distributions from each other, so that the light bands transmitted to the corresponding pixels are different or partially overlap.

4. The photoelectric sensor according to claim 1, wherein Each of the plurality of super pixel units (101) is configured to perform phase modulation on the incident light (60), so that light signals of a portion of the light of different wavelength bands are converted into electrical signals by pixels of the corresponding wavelength band; the portion of the wavelength band includes at least two wavelength bands.

5. The photoelectric sensor according to claim 1, wherein: The plurality of super pixel units (101) include a first super pixel unit (102) and a second super pixel unit (103); The plurality of receiving units (201) include a first receiving unit (202) arranged corresponding to the first super pixel unit (102) and a second receiving unit (203) arranged corresponding to the second super pixel unit (103); the first receiving unit (202) includes a first pixel (211) and a second pixel (212); the second receiving unit (203) includes a third pixel (213) and a fourth pixel (214); The first superpixel unit (102) is configured such that after light of different wavelengths passes through the first superpixel unit (102), the first wavelength band light and the second wavelength band light are modulated by the first superpixel unit (102) and transmitted to the first pixel (211) and the second pixel (212) respectively; the second superpixel unit (103) is configured such that after light of different wavelengths passes through the second superpixel unit (103), the third wavelength band light and the fourth wavelength band light are modulated by the second superpixel unit (103) and transmitted to the third pixel (213) and the fourth pixel (214) respectively; The first pixel (211) is configured to convert the optical signal of the first wavelength band into an electrical signal; The second pixel (212) is configured to convert the optical signal of the second wavelength band into an electrical signal; The third pixel (213) is configured to convert the optical signal in the third wavelength band into an electrical signal; The fourth pixel (214) is configured to convert the optical signal of the fourth wavelength band into an electrical signal.

6. The photoelectric sensor according to claim 5, characterized in that The first band is a red band; The second band and the fourth band are green bands; The third wavelength band is a blue wavelength band.

7. The photoelectric sensor according to claim 1, wherein: Each of the plurality of metalenses (10) comprises a nanostructure (11) and a substrate (12); The phase distribution of each of the plurality of metalenses (10) at least satisfies: ； ； ； in: is the wavelength number of the incident light (60), i=1,2,3, or i=1,2,3,4; The wavelength that needs to be modulated is different; is the effective focal length of each of the plurality of metalenses (10); is the coordinate position of the surface of the substrate (12) close to the nanostructure (11); The wavelength is The light spot formed by the incident light (60) on the photoelectric sensor is relative to the detection wavelength The offset position of the center point of the photoelectric sensor; 、 and For the wavelength The phase bias constant under ; 、 and is the maximum order of the phase coefficient; 、 and The wavelengths are Next Level, first Stage or The phase coefficient of the order.

8. The photoelectric sensor according to claim 1, wherein: The maximum refraction angle of each superlens (10) in the plurality of superlenses At least meet: 。 9. An optical device, characterized in that: The optical device comprises an optical system and a photosensor according to any one of claims 1 to 8; The photoelectric sensor is located at the image plane of the optical system.

10. A light modulation method, characterized in that: Applicable to the photoelectric sensor according to any one of claims 1 to 8, the method comprising: Providing a plurality of super lenses (10) arranged in an array, and dividing each of the plurality of super lenses (10) into a plurality of super pixel units (101); A plurality of receiving units (201) are provided in one-to-one correspondence with the plurality of super pixel units (101); each of the plurality of receiving units (201) includes a plurality of pixels (21); each of the plurality of pixels (21) is configured to convert an optical signal of a specific wavelength band into an electrical signal; Each super pixel unit (101) performs phase modulation on the incident light (60), so that light of different wavelength bands is respectively transmitted to pixels matching the wavelength band in the receiving unit corresponding to the super pixel unit; The phase distribution of the plurality of super pixel units (101) is designed differentially, so that the plurality of super pixel units (101) include at least two types of super pixel units, and the phase distributions of the at least two super pixel units are different from each other so that the light bands transmitted to the corresponding pixels are different or partially overlap.

Images