DETECTOR FOR DETECTING ELECTROMAGNETIC RADIATION, IMAGE SENSOR, AND METHOD FOR DETECTING IMAGE INFORMATION - Patent application

Abstract

The detector for detecting electromagnetic radiation includes an array (202) of funnel elements (102) for propagating the electromagnetic radiation from the second plane toward the first plane, wherein an entrance end (104) of the array (202) of funnel elements (102) defines the second plane, the entrance end (104) having a size greater than half the longest wavelength of the electromagnetic radiation to capture the electromagnetic radiation focused at the second plane, and an exit end (106) of the funnel elements (102) having a size less than half the first wavelength of the electromagnetic radiation; and an array (204) of photosensitive elements (110) for detecting the electromagnetic radiation defining the first plane, wherein each funnel element (102) is associated with a photosensitive element (110) such that image information corresponding to the electromagnetic radiation focused at the second plane and the first plane is detected by the array (204).

Description

[Technical field]

[0001] The present invention relates to a detector for detecting electromagnetic radiation, an image sensor and a method for detecting image information, in particular the invention relates to the detection of three-dimensional information. [Background technology]

[0002] Electromagnetic radiation, including for example ultraviolet, visible or infrared wavelengths, is useful as an information carrier in many different applications, and therefore a variety of detectors are employed to record and convert the electromagnetic radiation into electrical signals that can be processed and analyzed.

[0003] An imaging device can record electromagnetic radiation to obtain a two-dimensional image representative of an environment. However, in many applications, three-dimensional information may be desired, and it is desirable to include depth information in the obtained two-dimensional image information. Depth information can also be extracted by image processing of the obtained two-dimensional image, but such depth information may be limited by the depth of field of the imaging element.

[0004] Alternatively, depth information can be obtained by recording additional information, such as by using multiple imagers. However, it would be desirable to be able to obtain three-dimensional image information using a single imager, so that the acquisition of three-dimensional image information can be performed quickly and without the need for complex equipment. Summary of the Invention

[0005] It is an object of the present invention to enable rapid acquisition of three-dimensional image information with a relatively simple device. A particular object of the inventive concept is to provide a detector for detecting electromagnetic radiation constituting three-dimensional information.

[0006] These and other objects of the inventive concept are at least partly met by the invention as defined in the independent claims. Preferred embodiments are set forth in the dependent claims.

[0007] According to a first aspect, there is provided a detector for detecting electromagnetic radiation ranging from a first wavelength to a second wavelength, the first wavelength being the shortest wavelength in the range and the second wavelength being the longest wavelength in the range, the detector comprising an array of funnel elements for propagating the electromagnetic radiation from a second plane towards the first plane, each of the funnel elements including an entrance end and an exit end, the entrance ends of the array of funnel elements defining the second plane, the entrance ends having a size greater than half the second wavelength of the electromagnetic radiation in a medium from which the electromagnetic radiation enters the detector to capture focused electromagnetic radiation at the second plane. an array of funnel elements having an exit end having a size less than half a first wavelength of the electromagnetic radiation in the medium, and an array of photosensitive elements for detecting electromagnetic radiation incident on the array of photosensitive elements, each funnel element being associated with a photosensitive element such that image information corresponding to the electromagnetic radiation focused at a second plane is detected by the array of photosensitive elements, the array of photosensitive elements defining a first plane and configured to further capture image information corresponding to the electromagnetic radiation focused at the first plane.

[0008] Thanks to the detector, electromagnetic radiation focused in two different planes can be detected with the same array of photosensitive elements. Image information corresponding to two different image planes can therefore be detected with one exposure. The two different image planes correspond to two different distances to the object being imaged, and the image information includes depth information providing three-dimensional information.

[0009] By virtue of the use of the funnel element, the electromagnetic radiation focused at the entrance end of the funnel element is trapped within the funnel element for propagation within the funnel element to the exit end, so that the electromagnetic radiation corresponding to the spot imaged in the second plane can maintain a small spatial spread while propagating within the funnel element towards the first plane.

[0010] Since the entrance end is larger than half the longest wavelength to be detected, the electromagnetic radiation focused at the second plane is captured to propagate in the funnel element. Meanwhile, the electromagnetic radiation not focused at the second plane, e.g., electromagnetic radiation focused at the first plane, may have a spot size at the second plane that is substantially larger than the entrance end of the funnel element and may pass through the funnel element to the first plane such that the electromagnetic radiation propagates unaffected to the first plane without observing any refraction or guidance from the funnel entrance, with the funnel element having substantially no effect on the electromagnetic radiation. Thus, the electromagnetic radiation corresponding to the spot imaged at the first plane may be captured in focus at the first plane. Also, since the exit end of the funnel element has a size smaller than half the shortest wavelength, i.e., smaller than the diffraction limit for imaging, the electromagnetic radiation will not be captured by the funnel element along the extension of the funnel element between the second plane and the first plane, and therefore the funnel element will not affect the imaging of the electromagnetic radiation focused at the first plane.

[0011] As mentioned above, the entrance end has a size larger than half the longest wavelength to be detected. However, since the size of the entrance end affects the resolution of the imaging by the detector, the entrance end can be selected in relation to the desired resolution. For example, to enable imaging at the maximum resolution, the entrance end can be as small as possible while still having a size larger than half the longest wavelength.

[0012] The electromagnetic radiation detected by the detector may span a relatively wide wavelength range. For example, the detector may detect electromagnetic radiation in the ultraviolet range and / or the visible range and / or the infrared range, e.g., short wavelength infrared. In an embodiment, the detector may detect electromagnetic radiation in the visible range, such as electromagnetic radiation ranging from 380 to 740 nm, or electromagnetic radiation ranging from 400 to 700 nm, or electromagnetic radiation ranging from 440 to 660 nm.

[0013] The wavelength of the electromagnetic radiation depends on the refractive index of the medium through which the electromagnetic radiation propagates. Thus, the spot size may be affected by the medium through which the electromagnetic radiation propagates. The electromagnetic radiation may propagate through the medium from which it enters the detector to reach the inlet end of the funnel element. Depending on the medium through which the electromagnetic radiation propagates, the spot size captured by the inlet end of the funnel element may therefore differ. Thus, the inlet end preferably has a size greater than half the second wavelength of the electromagnetic radiation, the second wavelength being defined by the medium through which the electromagnetic radiation enters the detector. It should be understood that the electromagnetic radiation may enter the detector as it enters the inlet end of the funnel element. However, there may be one or more layers integral with the funnel element such that the electromagnetic radiation may enter such layers before reaching the inlet end of the funnel element. For example, as described below, the detector may comprise an additional array of funnel elements on top of the array of funnel elements. As used herein, the medium from which the electromagnetic radiation enters the detector should be interpreted as the medium through which the electromagnetic radiation enters the material integral with the array of funnel elements. Typically, before reaching the entrance end of the funnel element, the electromagnetic radiation propagates through air, which has a refractive index of about 1. However, according to embodiments, the entrance end of the funnel element may be immersed in another medium, such as water or immersion oil, to provide a medium of different refractive index through which the electromagnetic radiation propagates, such that the entrance end of the funnel element is smaller while still capturing the electromagnetic radiation at a focus in the second plane.

[0014] The funnel elements of the array may extend in parallel between the inlet and outlet ends.

[0015] It should be understood that the inlet and outlet ends of the funnel element may have any shape. The size of the inlet and outlet ends should be interpreted as the maximum dimension of the inlet and outlet ends between the opposing side walls of the funnel element. Thus, for rectangular inlet and outlet ends, the size of the inlet and outlet ends will correspond to the larger of the width and height of the rectangle. For circular inlet and outlet ends, the size of the inlet and outlet ends will correspond to the diameter of the circular shape. According to an embodiment, the inlet and outlet ends of the funnel element are square-shaped.

[0016] The exit ends of the funnel elements may be located in the first plane or may be located close to the first plane. However, according to an alternative, each funnel element may transition into a waveguide having a constant or slowly varying (e.g. slightly tapered) cross section along the length of the waveguide. In such a case, the exit ends of the waveguide may be located in the first plane or may be located close to the first plane.

[0017] The funnel elements or waveguides may be aligned with one another such that the respective exit ends, through which the guided electromagnetic radiation exits the funnel elements or waveguides, are located on or at the same distance from the array of photosensitive elements, preferably with the exit ends located as close as possible to or abutting the photosensitive elements, to provide a near-field configuration and allow further miniaturization of the detector.

[0018] According to an embodiment, the funnel element has at least one side wall that is non-parallel to an extension of the funnel element from the inlet end to the outlet end.

[0019] Thus, a reduction in the cross-sectional size of the funnel element between the inlet end and the outlet end may be provided by at least one side wall being non-parallel to the extension of the funnel element.

[0020] Preferably, all side walls of the funnel element are equally tapered such that the funnel element is symmetric about a line perpendicular to the inlet and outlet ends.

[0021] According to an embodiment, an adiabatic taper of the funnel element is provided such that the angle of the sidewalls relative to the normal of the inlet and outlet ends increases towards the outlet end, which is advantageous in ensuring that electromagnetic radiation captured at the inlet end propagates within the funnel element to the outlet end, which is important when a steep taper of the funnel element is used.

[0022] However, according to other embodiments, at least one side wall may extend along a straight line between the inlet end and the outlet end, which means that the shape of the funnel element is simple and still provides a funnel element that effectively propagates electromagnetic radiation captured at the inlet end to the outlet end, especially if the length of the funnel element is greater than or much greater than the order of magnitude of the wavelength of the electromagnetic radiation.

[0023] According to an embodiment, the detector further comprises a first array of waveguides, each waveguide configured to direct electromagnetic radiation from the exit end of the funnel element to the photosensitive element.

[0024] Electromagnetic radiation captured at the inlet end of the funnel element may be guided through the funnel element to the outlet end and then guided from the outlet end to the photosensitive element by the waveguide. In this manner, the electromagnetic radiation may be guided through both the funnel element and the waveguide. The funnel element and the waveguide may be integrally formed. In this manner, the funnel element and the waveguide may form different sections within one component.

[0025] The change in cross section along the length of the section may be different for funnel elements and waveguides. Thus, a funnel element may be referred to as a funnel element since the rate of change of cross-sectional size along the funnel element may be relatively large compared to the rate of change of cross-sectional size along the waveguide. For example, a waveguide may have a constant or nearly constant cross section along its length. A waveguide may alternatively be tapered such that the angle between the sidewall of the waveguide and the cross section of the waveguide is less than 90°, for example about 85°. This may be useful in the manufacture of detectors since the waveguide may be formed with an etching process that provides an etch angle.

[0026] According to an embodiment, the waveguide includes a first waveguide section and a second waveguide section, the first waveguide section configured to guide electromagnetic radiation within a wavelength range, the second waveguide section extending parallel to the first waveguide section and configured to selectively guide electromagnetic radiation within a sub-range of the wavelength range, and the second waveguide section coupled to the first waveguide section and configured to out-couple electromagnetic radiation from the first waveguide section within the sub-range of the wavelength range.

[0027] Outcoupling of the sub-range electromagnetic radiation from the first waveguide section allows for color separation of the incident light, which can increase the sensitivity of the detector, particularly in relation to other techniques that utilize color filters to filter different wavelengths from the incident light. By using outcoupling of the sub-range electromagnetic radiation from the first waveguide section, it is possible to distinguish different wavelengths without using color filters to control the wavelengths that reach the light receiving element.

[0028] The first waveguide section may be referred to as a "full spectrum" waveguide, which should be understood as a waveguide capable of guiding a wider range of wavelengths than the second waveguide section. Preferably, the first waveguide section is a full spectrum waveguide in the sense that, in use, it may transmit electromagnetic radiation in the visible wavelength range. The first waveguide section may be designed in relation to the electromagnetic radiation to be guided by the first waveguide section. Thus, the dimensions of the first waveguide section need not be limited for use with a single particular wavelength of electromagnetic radiation. Rather, the first waveguide section may be used with a range of predetermined wavelengths while providing the desired propagation characteristics.

[0029] The second waveguide section may be referred to as a "color separation" waveguide, referring to its ability to couple electromagnetic radiation within a sub-range of the wavelength range of the electromagnetic radiation received by the first waveguide section. The second waveguide section may thus be understood as a waveguide capable of filtering out specific colors of incident visible light, such as sub-ranges of the wavelength range corresponding to, for example, red, green or blue light. Similar to the first waveguide section, the second waveguide section may therefore be designed in relation to the electromagnetic radiation to be guided by the second waveguide section. The dimensions of the second waveguide section therefore need not be limited for use with a particular wavelength of electromagnetic radiation, but may be used with sub-ranges of wavelengths corresponding to, for example, the red, green or blue spectrum, while providing the desired propagation characteristics.

[0030] According to an embodiment, the array of funnel elements is a first array of funnel elements, and the detector further comprises a second array of funnel elements for propagating electromagnetic radiation from the third plane towards the first plane, each of the second array of funnel elements comprising an entrance end and an exit end, the second array of funnel elements comprising an entrance end, wherein the entrance end of the second array of funnel elements defines a third plane, the entrance end has a size greater than half a second wavelength of the electromagnetic radiation in the medium to capture the electromagnetic radiation focused at the third plane, and the exit end has a size less than half a first wavelength of the electromagnetic radiation in the medium.

[0031] Thanks to the second array of funnel elements defining a third plane, focused electromagnetic radiation in additional planes (three different planes) can be detected with the same array of photosensitive elements. Image information corresponding to three different image planes can therefore be detected in one exposure. This means that further depth information is obtained to improve the three-dimensional information.

[0032] It should be appreciated that the detector may include one or more additional arrays of funnel elements such that image information from further image planes may be captured. Thus, adding additional arrays of funnel elements may ensure that more depth information is captured by the detector.

[0033] According to an embodiment, the detector further includes an array of intermediate waveguides, each intermediate waveguide configured to direct electromagnetic radiation from an exit end of the second array of funnel elements to an entrance end of the first array of funnel elements.

[0034] The electromagnetic radiation captured at a focus in the third plane can propagate through the funnel elements, and possibly through intermediate waveguides, to reach the entrance ends of the funnel elements of the first array. Thus, the electromagnetic radiation corresponding to the spot imaged on the third plane will maintain a small spatial extent in the second plane defined by the entrance ends of the funnel elements of the first array. Thus, the electromagnetic radiation focused in the third plane can also be captured at the entrance ends of the funnel elements of the first array, where it can be further propagated towards the first plane.

[0035] The funnel elements and the intermediate waveguide of the second array may be integrally formed. In this way, the funnel elements and the intermediate waveguide may form different sections within a single component.

[0036] The change in cross section along the length of the section may be different for the funnel element and the intermediate waveguide. Thus, the funnel element may be referred to as a funnel element since the rate of change of the cross-sectional size along the funnel element may be relatively large compared to the rate of change of the cross-sectional size along the waveguide. For example, the intermediate waveguide may have a constant or nearly constant cross section along its length. The intermediate waveguide may alternatively be tapered such that the angle between the sidewall of the intermediate waveguide and the cross section of the intermediate waveguide is less than 90°, for example about 85°. This may be useful in the manufacture of detectors since the intermediate waveguide may be formed with an etching process that provides an etch angle.

[0037] In an embodiment, some intermediate waveguides in the array of intermediate waveguides may extend from the third plane to the second plane and may not be associated with a funnel element of the second array. This means that such intermediate waveguides that are not associated with a funnel element will not contribute to additional capture of electromagnetic radiation in the third plane. This may facilitate the extraction of image information corresponding to the electromagnetic radiation focused in the second plane (as not all photosensitive elements that receive such image information also receive image information corresponding to the electromagnetic radiation focused in the third plane) while allowing additional capture of electromagnetic radiation to be performed.

[0038] According to another embodiment, the detector further includes a second array of waveguides, each waveguide of the second array configured to direct electromagnetic radiation from an exit end of a funnel element of the second array to a photosensitive element.

[0039] This means that electromagnetic radiation can be guided through the waveguides of the second array from the third plane, across the second plane, to the first plane, and therefore electromagnetic radiation captured by the funnel elements of the second array will not be captured by the funnel elements of the first array.

[0040] Thus, the waveguides of the second array may extend through the second plane, with each waveguide of the second array disposed between adjacent inlet ends of the funnel elements of the first array. However, the cross-sections of the waveguides of the second array may be relatively small in the second plane and therefore may not substantially impede capture of electromagnetic radiation in the second plane.

[0041] Thanks to the waveguides of the second array that direct the electromagnetic radiation to the photosensitive elements, different photosensitive elements can receive image information corresponding to the electromagnetic radiation focused in the third plane and in the second plane, respectively. This means that the extraction of image information corresponding to each image plane can be simplified, since each individual photosensitive element captures information related to fewer image planes.

[0042] According to an embodiment, the array of photosensitive elements comprises different sets of photosensitive elements for capturing image information corresponding to electromagnetic radiation focused at different planes.

[0043] It should be understood that electromagnetic radiation that is not captured for transfer to a particular photosensitive element still reaches the array of photosensitive elements, but the resulting spot is larger for unfocused electromagnetic radiation such that the corresponding intensity of electromagnetic radiation at a single photosensitive element is smaller. This means that image information captured in focus and transferred to a dedicated photosensitive element will have a high intensity at the dedicated photosensitive element, in that different sets of photosensitive elements may detect high intensity electromagnetic radiation relative to electromagnetic radiation that is focused at different planes.

[0044] By having different sets of photosensitive elements dedicated to electromagnetic radiation at focal points at different planes, a particular set of photosensitive elements can be selected for analysis when image information corresponding to a particular depth within the image is of interest.

[0045] According to an embodiment, the funnel element is formed from a high refractive index material and is surrounded by a low refractive index material.

[0046] As used herein, a high refractive index material should be interpreted as a material that has a refractive index that is at least greater than the refractive index of the low refractive index material that surrounds it.

[0047] This means that electromagnetic radiation captured by the funnel element is prevented from leaving the funnel element into the surrounding material due to total internal reflection of the electromagnetic radiation in the funnel element.

[0048] Thanks to the funnel element being made of a high refractive index material, the wavelength of the electromagnetic radiation will be small in the funnel element (e.g. compared to the wavelength of the electromagnetic radiation in air). This means that the exit end of the funnel element can be made very small and the electromagnetic radiation can be directed to a very small photosensitive element, which can be much smaller than the wavelength of the electromagnetic radiation in air. This means that high resolution imaging can be achieved even if the pitch between the photosensitive elements is very small and different photosensitive elements are dedicated to receiving image information corresponding to electromagnetic radiation focused at different planes.

[0049] In an embodiment, the high refractive index material is silicon nitride, Si3N4, while the low refractive index material is silicon dioxide, S i It's O2.

[0050] According to an embodiment, a photosensitive element includes a photoactive layer for generating a signal corresponding to an amount of electromagnetic radiation incident on the photoactive layer.

[0051] The photoactive layer may preferably have a very short absorption length to facilitate absorption of incident electromagnetic radiation. The photoactive layer may include, for example, perovskite materials, organic materials, quantum dots, and / or amorphous germanium.

[0052] According to an embodiment, the photosensitive device further includes an interconnect layer for transmitting signals from the photoactive layer to the semiconductor circuitry.

[0053] A photosensitive element is understood as an element capable of converting incident electromagnetic radiation, such as visible light, into an electrical signal. The photosensitive element may be composed of, for example, a contact layer, a photoactive layer, and an interconnect layer arranged on a semiconductor substrate. The photoactive layer may be arranged to convert photons into an electrical current. The interconnect layer may be arranged between the photoactive layer and the substrate. The interconnect layer may include electrodes for conducting the electrical current in the photoactive layer to electrical circuits and devices suitable for reading and processing the electrical signal. The contact layer may be an unpatterned layer that extends as a uniform layer between the photosensitive element and a waveguide for transmitting electromagnetic radiation to the photoactive layer. The photoactive layer may be patterned into separate areas, for example corresponding to each of the waveguides, or may be formed as a uniform layer extending below the waveguides. In some embodiments, the interconnect layer may be patterned into a plurality of electrodes or electrode regions that may be aligned, for example, with a respective one of the waveguides.

[0054] Thus, the interconnect layer may include a first electrode associated with the first waveguide section and a second electrode associated with the second waveguide section, The first electrode may be disposed below the first waveguide section to register electromagnetic radiation guided through the first waveguide section, while the second electrode may be disposed below the second waveguide section to register electromagnetic radiation guided through the second waveguide section.

[0055] Furthermore, the first and second electrodes and / or the portions of the photoactive layer arranged between the first and second electrodes and the respective waveguide sections may have thicknesses individually tailored to the specific wavelength range to be detected that can be determined by the first and second waveguide sections, respectively. Thus, the electrodes and / or photoactive layer portions under the first waveguide section may be thicker and the electrodes and / or photoactive layer portions under the second waveguide section may be thicker, or vice versa. This can advantageously improve the overall performance of the photosensitive element.

[0056] According to an embodiment, the detector includes an array of funnel elements and a single lens for focusing incident electromagnetic radiation towards the array of photosensitive elements.

[0057] Thus, the detector may provide for capture of image information, including depth information providing three dimensional information, using a single lens, without the need to provide movement of the lens relative to the array of photosensitive elements.

[0058] According to an embodiment, the detector further includes a filter for extracting image information corresponding to the electromagnetic radiation focused at a particular plane.

[0059] The detector allows for the capture of image information including depth information providing three-dimensional information. The filter may be configured to extract image information corresponding to a particular plane from the captured image information. In this manner, information at a particular depth may be selectively extracted from the captured image information.

[0060] The filters may be provided as software instructions for causing a processing device to extract image information, however, the filters may alternatively be provided as hardware configured to process the captured image information.

[0061] According to a second aspect, there is provided an image sensor including a detector according to the first aspect, the image sensor configured to detect three-dimensional image information based on simultaneously capturing image information in at least two image planes.

[0062] The advantages and features of this second aspect are generally similar to those described above in relation to the first aspect, and the embodiments described in relation to the first aspect are generally compatible with the second aspect.

[0063] The image sensor may use the detector of the first aspect to simultaneously capture image information corresponding to electromagnetic radiation focused in at least two different image planes. The image sensor may therefore detect three-dimensional image information in one exposure. This means that the image sensor can capture three-dimensional image information very quickly (in one exposure), while being simple and only requiring a single array of photosensitive elements.

[0064] According to a third aspect, there is provided a method for detecting image information, the method comprising the steps of capturing electromagnetic radiation ranging from a first wavelength to a second wavelength, the first wavelength being the shortest wavelength in the range and the second wavelength being the longest wavelength in the range, the electromagnetic radiation being captured with an array of funnel elements for propagating the electromagnetic radiation from a second plane towards the first plane, an entrance end of each funnel element having a size greater than half the second wavelength of the electromagnetic radiation in a medium through which the electromagnetic radiation enters a detector to capture the electromagnetic radiation focused at the second plane; detecting, at an array of photosensitive elements, the electromagnetic radiation captured by the array of funnel elements to detect image information corresponding to the electromagnetic radiation focused at the second plane while simultaneously detecting the electromagnetic radiation that has passed through the array of funnel elements to detect image information corresponding to the electromagnetic radiation focused at the first plane.

[0065] The advantages and features of this third aspect are generally similar to those described above in relation to the first and second aspects, and the embodiments described in relation to the first and second aspects are generally compatible with the third aspect.

[0066] Simultaneous detection of focused electromagnetic radiation in different planes allows for very rapid capture of three-dimensional image information. [Brief description of the drawings]

[0067] The above, as well as additional objects, features and advantages of the inventive concept will become better understood through the following illustrative and non-limiting detailed description taken in conjunction with the accompanying drawings in which like reference numerals are used for like elements, unless otherwise noted, in which:

[0068] [Figure 1] FIG. 1 is a schematic diagram of a configuration including a funnel element and a waveguide for guiding electromagnetic radiation, illustrating capture of electromagnetic radiation. [Diagram 2] FIG. 1 is a schematic diagram of a detector according to a first embodiment. [Diagram 3] FIG. 1 is a schematic diagram of a photosensitive element according to one embodiment. [Figure 4] FIG. 11 is a schematic diagram of a detector according to a second embodiment. [Diagram 5] 4 is a graph showing the intensity detected by a photosensitive element in relation to focused photons at different distances. [Figure 6] FIG. 11 is a schematic diagram of a detector according to a third embodiment. [Figure 7] FIG. 13 is a schematic diagram of a detector according to a fourth embodiment. [Figure 8] FIG. 13 is a schematic diagram of a detector according to a fourth embodiment extended with the possibility of performing color separation. [Figure 9] FIG. 1 is a schematic diagram of an image sensor according to one embodiment. [Figure 10] 1 is a flowchart of a method according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] With reference to FIG. 1, detection of focused electromagnetic radiation in multiple image planes will be described.

[0070] In Fig. 1, an arrangement 100 for guiding electromagnetic radiation is shown. The arrangement 100 includes a funnel element 102 for capturing electromagnetic radiation. As shown in Fig. 1, the funnel element 102 may be configured to capture electromagnetic radiation focused at an entrance end 104 of the funnel element 102. Thus, electromagnetic radiation corresponding to a spot to be imaged at the entrance end 104 of the funnel element 102 may be propagated within the funnel element 102, and the electromagnetic radiation may be guided towards a photosensitive element 110 associated with the funnel element 102. This means that image information corresponding to the electromagnetic radiation focused at the entrance end 104 of the funnel element 102 may be received such that image information corresponding to a plane in which the funnel element 102 is located is sharp in the plane in which the photosensitive element 110 is located.

[0071] The funnel element 102 may be tapered between the entrance end 104 and the exit end 106. The entrance end 104 may have a size larger than half the wavelength of the electromagnetic radiation, while the exit end 106 may have a size smaller than half the wavelength of the electromagnetic radiation. As a result, the electromagnetic radiation focused at the entrance end 104 is captured by the funnel element 102 for propagating therethrough. However, the funnel element 102 is transparent to electromagnetic radiation having a spot or beam diameter larger than about half the wavelength of the electromagnetic radiation, which means that electromagnetic radiation that is not focused at the entrance end 104 of the funnel element 102 may pass through the funnel element 102 unaffected towards the photosensitive element 110. This means that the photosensitive element 110 may receive electromagnetic radiation focused at the plane of the entrance end 104 of the funnel element 102 as well as electromagnetic radiation focused at the plane of the photosensitive element 110. Thus, the photosensitive element 110 can capture image information that is focused at two planes: the plane of the entrance end 104 of the funnel element 102 and the plane of the photosensitive element 110 .

[0072] It should be understood that the photosensitive elements 110 may also receive unfocused electromagnetic radiation at the aforementioned planes, however the unfocused spot size will be spread across many of the photosensitive elements 110 such that the intensity of the electromagnetic radiation at a single photosensitive element 110 is small and does not affect the ability to sharply image focused electromagnetic radiation at the plane of the entrance end 104 of the funnel element 102 and the plane of the photosensitive elements 110.

[0073] The electromagnetic radiation to be detected using the photosensitive element 110 may span a relatively wide range of wavelengths from a first shortest wavelength to a second longest wavelength. For example, electromagnetic radiation in the ultraviolet range, such as short wavelength infrared, and / or in the visible range and / or in the infrared range may be detected. In an embodiment, electromagnetic radiation in the visible range may be detected, such as electromagnetic radiation ranging from 380 to 740 nm, or electromagnetic radiation ranging from 400 to 700 nm, or electromagnetic radiation ranging from 440 to 660 nm.

[0074] The wavelength of the electromagnetic radiation depends on the refractive index of the medium through which the electromagnetic radiation propagates. Thus, the spot size may be affected by the medium through which the electromagnetic radiation propagates. The electromagnetic radiation may propagate in a medium before reaching the entrance end 104 of the funnel element 102. Thus, the spot size captured by the entrance end 104 of the funnel element 102 may vary depending on the medium through which the electromagnetic radiation propagates. Thus, the entrance end 104 preferably has a size larger than half of the second wavelength of the electromagnetic radiation, the second wavelength being defined by the medium through which the electromagnetic radiation propagates before reaching the entrance end 104 of the funnel element 102. Typically, the electromagnetic radiation propagates in air, which has a refractive index of about 1, before reaching the entrance end 104 of the funnel element 102. However, according to embodiments, the entrance end 104 of the funnel element 102 may be immersed in another medium, such as water or immersion oil, to provide a different refractive index of the medium through which the electromagnetic radiation propagates, allowing the entrance end 104 of the funnel element 102 to be smaller while still capturing the electromagnetic radiation that is focused at the entrance end 104 of the funnel element 102.

[0075] As shown in FIG. 1, the entrance end 104 of the funnel element 102 can capture electromagnetic radiation corresponding to a range of distances between the lens and the object. In the embodiment shown in FIG. 1, the lens has a focal length of 6 mm, and the entrance end 104 of the funnel element 102 is located at a distance of 3.6 μm below the focal plane of the lens, i.e., 6.0036 mm from the lens. The funnel element 102 is configured to capture electromagnetic radiation from a distance of about 9-11.5 m from the lens, and the configuration 100 is optically transparent for electromagnetic radiation from different distances. The range of distances at which electromagnetic radiation is captured shown above applies to green light (wavelength 550 nm). It should be appreciated that the ranges are slightly different for other wavelengths, e.g., 9.3-11.2 m for red light and 8.3-11.9 m for blue light, but electromagnetic radiation is still captured from approximately the same range of distances for different wavelengths.

[0076] The size of the inlet end 104 and the outlet end 106 should be interpreted as the maximum dimension of the inlet end and the outlet end between the opposing side walls of the funnel element 102. Thus, the size of the inlet end 104 and the outlet end 106 may correspond to the side of a square shape or the diameter of a circular shape.

[0077] Funnel element 102 may be tapered symmetrically about a line perpendicular to inlet end 104 and outlet end 106. For example, if funnel element 102 has a square cross section, all of the side walls may have equal angles between inlet end 104 and outlet end 106.

[0078] The funnel element 102 may have a relatively gradual taper by having a relatively long distance between the inlet end 104 and the outlet end 106 compared to the difference in size between the inlet end 104 and the outlet end 106. For example, as shown in FIG. 1, the angle between the sidewall of the funnel element 102 and the cross section of the intermediate waveguide may be about 85°.

[0079] As shown in FIG. 1, the configuration 100 may include two sections, where the funnel element 102 transitions into a second section, referred to herein as a waveguide 108. As shown in FIG. 1, the funnel element 102 may have a tapered cross section, while the waveguide 108 may have a constant cross section. The two sections of the configuration 100 may differ in that the rate of change in cross-sectional size is greater for the funnel element 102 than for the waveguide 108. However, the waveguide 108 may also have a tapered cross section. For example, the funnel element 102 may have a steep taper followed by a waveguide with a gradual taper. This may be particularly useful when the inlet end 104 of the funnel element 102 is relatively large.

[0080] Funnel element 102 may have a constant rate of change in cross-sectional size such that funnel element 102 comprises planar sidewalls. However, if a particularly steep taper is used, the sidewalls of funnel element 102 may be configured to provide an adiabatic taper.

[0081] Configuration 100 does not necessarily include two sections. Rather, configuration 100 may be comprised solely of funnel element 102, such that exit end 106 of funnel element 102 is also the exit end of configuration 100, and configuration 100 does not comprise a waveguide 108.

[0082] The arrangement 100 may be placed directly on the photosensitive element 110 such that an end face (of the funnel element 102 or the waveguide 108) through which the guided light can exit the arrangement 100 is in direct contact with the photosensitive element 110. However, it should be noted that alternatively there may be a small distance between the end face of the arrangement 100 and the photosensitive element 110.

[0083] The arrangement 100 may be formed from a high refractive index material and may be surrounded by a low refractive index material. The funnel element 102 may thus be configured to propagate electromagnetic radiation therein using total internal reflection.

[0084] The high refractive index material may also mean that the wavelength of the electromagnetic radiation will be small within the funnel element 102 compared to the wavelength of the electromagnetic radiation in air. This means that the exit end 106 of the funnel element 102 may be very small, allowing the electromagnetic radiation to be directed to a very small photosensitive element 110, which may be much smaller than the wavelength of the electromagnetic radiation in air.

[0085] In an embodiment, the high refractive index material is silicon nitride, Si3N4, while the low refractive index material is silicon dioxide, SiO2, however, it should be understood that other materials that provide a high refractive index may be used.

[0086] 2, a detector 200 will now be described. The detector 200 is comprised of an array 202 of funnel elements 102 in the configuration 100, as described above with reference to FIG. 1. The detector 200 further includes an array 204 of photosensitive elements 110, with each funnel element 102 associated with a photosensitive element 110 of the array 204.

[0087] The array 204 of photosensitive elements 110 may define a first plane. The array of photosensitive elements 110 may be configured to detect image information corresponding to electromagnetic radiation focused at the first plane.

[0088] The entrance ends 104 of the funnel elements 102 of the array 202 may further define a second plane. Due to the capture of the electromagnetic radiation focused at the second plane by the funnel elements 102 and the propagation of the captured electromagnetic radiation towards the photosensitive elements 110 by the array 202 of funnel elements 102 and the array of waveguides 108, the array of photosensitive elements 110 may be further configured to detect image information corresponding to the electromagnetic radiation focused at the second plane.

[0089] Thus, the detector 200 may provide two focal planes such that image information may be captured by the detector 200 that provides depth information in addition to the two-dimensional imaging provided by the array 204 of photosensitive elements 110. This means that the detector 200 is configured to capture three-dimensional image information, and the detector 200 can also capture the three-dimensional image information using a single array 204 of photosensitive elements 110 in a single exposure, without the need for moving parts.

[0090] 3, a photosensitive element 110 is disclosed according to one embodiment. The photosensitive element 110 may include a photoactive layer 114 configured to be photoelectrically responsive to photons, thereby enabling directed electromagnetic radiation to form a measurable electrical signal. The photoactive layer 114 may be, for example, a layer of amorphous silicon, amorphous germanium, perovskite, an organic material, or quantum dots.

[0091] The photoactive layer 114 may be covered by a contact layer 112, such as an optically transparent, electrically conductive layer, disposed between the photoactive layer 114 and the structure 100. The contact layer 112 may include, for example, indium tin oxide, ITO.

[0092] The photoactive layer 114 may be disposed on a substrate 118, which may be a front-end-of-line substrate including transistors and other devices for processing electrical signals generated by the guided electromagnetic radiation, such as a silicon substrate 118. Additionally, an interconnect layer 116 may be disposed between the photoactive layer 114 and the substrate 118 for transmitting signals therebetween. The interconnect layer 116 may include a number of electrodes, each of which is disposed to contact the photoactive layer 114 at a location corresponding to where the guided electromagnetic radiation is transmitted to the photoactive layer 114 by the configuration 100. Preferably, the electrodes are disposed as close as possible to the configuration 100, such as within 500 nm or less.

[0093] 4, it should be understood that the concept of providing two focal planes may be extended to further focal planes. Thus, there may be one or more further arrays of funnel elements to define further planes in which focused electromagnetic radiation may be captured by the entrance ends of the funnel elements of the further arrays.

[0094] 4, a second array 210 of funnel elements 102, a third array 212 of funnel elements 102, and a fourth array 214 of funnel elements 102 are shown. There may further be arrays 216, 218, 220 of intermediate waveguides 222, which may be configured to direct electromagnetic radiation from the exit end 106 of the funnel element 102 downward to the entrance end 104 of the other array of funnel elements 102.

[0095] The funnel elements 102 of the second array 210, the third array 212, and the fourth array 214 may be tapered between the entrance end 104 and the exit end 106, like the funnel elements 102 of the array 202. The entrance end 104 may have a size greater than half the wavelength of the electromagnetic radiation, while the exit end 106 may have a size less than half the wavelength of the electromagnetic radiation. As a result, electromagnetic radiation that is focused at the entrance end 104 is captured by the funnel element 102 for propagating therethrough. However, the funnel element 102 is transparent to electromagnetic radiation having a spot or beam diameter greater than about half the wavelength of the electromagnetic radiation, which means that electromagnetic radiation that is not focused at the entrance end 104 of the funnel element 102 may pass through the funnel element 102 unaffected towards the photosensitive element 110.

[0096] Similar to waveguide 108, intermediate waveguide 222 may be integral with funnel element 102 and may form a second section of the structure for directing electromagnetic radiation from the entrance end 104 of one funnel element 102 downward to the entrance end 104 of the other funnel element 102.

[0097] The funnel element 102 may have a tapered cross section, while the intermediate waveguide 222 may have a constant cross section. The two cross sections of the configuration may differ in that the rate of change of cross-sectional size is greater for the funnel element 102 than for the intermediate waveguide 222. However, the intermediate waveguide 222 may have a tapered cross section. For example, the funnel element 102 may have a steep taper, followed by the intermediate waveguide 222, which has a gradual taper.

[0098] 5, there is shown the intensity detected by the photosensitive elements 110 in relation to photons focused at different distances for a detector 200 having a first array 202, a second array 210 and a third array 212 of funnel elements 102 as shown in FIG. 4 positioned above an array 204 of photosensitive elements 110, with each component of the funnel elements 102 and the waveguide 108 or intermediate waveguide 222 having a length of 2 μm. As can be seen from FIG. 5, there are intensity peaks of the photosensitive elements 110 corresponding to electromagnetic radiation focused at the entrance end 104 of the funnel elements 102 in either the first, second or third arrays 202, 210, 212.

[0099] It should further be appreciated that the image information detected by the array 204 of photosensitive elements 110 may be analyzed to extract specific depth information. For example, the detector 200 may further include a filter to extract specific image information corresponding to electromagnetic radiation focused at a particular plane.

[0100] The filter may be implemented in hardware, such as implemented on a silicon substrate 118, which may include transistors and other devices for processing the electrical signals generated by the guided electromagnetic radiation, or the filter may be implemented in software, such as provided as computer-executable instructions to a processing unit that may receive the electrical signals generated by the guided electromagnetic radiation.

[0101] For example, the filter may be implemented as a relatively simple high-pass filter and may be configured to detect the difference between an image region captured by the array 204 of photosensitive elements 110 being in focus and an image region being out of focus.

[0102] According to an exemplary embodiment, a compact camera having a lens with a focal length of 6 mm is used with an array of 6.6 μm photosensitive elements 204 located below the focal plane of the lens. The basic thin lens equation gives the following relationship between the distance (depth) of an object and a sharp image representation of that object:

[0103] Height of sharp image above array of photosensitive elements: 6.00 μm, Depth of object: 59.79 m Height of sharp image above array of photosensitive elements: 5.00 μm, Depth of object: 22.48 m Height of sharp image above array of photosensitive elements: 4.00 μm, Depth of object: 13.84 m Height of sharp image above array of photosensitive elements: 3.00 μm, Depth of object: 10.00 m Height of sharp image above array of photosensitive elements: 2.00 μm, depth of object: 7.83 m Height of sharp image above array of photosensitive elements: 1.00 μm, depth of object: 6.43 m Height of sharp image on array of photosensitive elements, depth of object: 5.46m

[0104] Thus, by placing funnel elements capturing electromagnetic radiation at six heights above the array 204 of photosensitive elements 110, namely 1, 2, 3, 4, 5 and 6 μm, respectively, depth information can be detected for object distances that are significantly different.

[0105] Next, with reference to Fig. 6, a detector 300 according to another embodiment will be described. In contrast to the detector 200 shown in Fig. 4, the detector 300 comprises a second array 310 of funnel elements 102 associated with a second array 316 of waveguides 322 configured to guide electromagnetic radiation from the funnel elements 102 to the photosensitive elements 110. The waveguides 322 may therefore extend beyond a second plane defined by the entrance ends 104 of the funnel elements 102 of the first array 202.

[0106] The waveguides 322 of the second array 316 and the waveguides 108 of the first array may therefore be configured to direct electromagnetic radiation to different sets of photosensitive elements 110 .

[0107] At first glance, this embodiment may seem to trade depth information for resolution of a two-dimensional image, but in reality, this is not exactly correct. The waveguides 322, 108, and corresponding photosensitive elements 110 can be much smaller than half the wavelength of light, especially since the electromagnetic radiation may be guided through a high refractive index material. Only the entrance end 104 of the funnel element 102 needs to be larger than the diffraction limit.

[0108] It should be appreciated that the embodiment shown in Figure 6 may be extended in a number of different ways. For example, there may be additional arrays of funnel elements 102 with intermediate waveguides on each of the first array 202 and second array 310 of funnel elements 102 such that focused electromagnetic radiation at additional image planes is captured and forwarded to the entrance ends 104 of the funnel elements 102 of each of the first array 202 and second array 310.

[0109] Alternatively or additionally, further arrays of funnel elements 102 may be provided having waveguides configured to direct electromagnetic radiation from the funnel elements 102 to the photosensitive elements 110. Thus, the waveguides may extend beyond the second plane defined by the entrance ends 104 of the funnel elements 102 of the first array 202 such that several parallel arrays of waveguides may be provided for directing electromagnetic radiation to different photosensitive elements 110.

[0110] 7, a detector 400 may comprise four different arrays 202, 410, 412, 414 of funnel elements 102 with the entrance ends 104 of the funnel elements 102 of the different arrays 202, 410, 412, 414 each positioned at a different height above the array 204 of photosensitive elements 110. The four different arrays 202, 410, 412, 414 may be arranged in a square configuration so as not to trade two-dimensional image resolution for depth information, or at least to maintain as high a two-dimensional image resolution as possible.

[0111] 8, it will be explained that the embodiment shown in FIG. 7 has been extended with the possibility of splitting introduction of electromagnetic radiation of different ranges of wavelengths. However, it will be understood that this splitting may be provided for any waveguide configured to direct electromagnetic radiation from funnel element 102 to photosensitive element 110, such as waveguide 108 or waveguide 322.

[0112] As shown in FIG. 8, each waveguide 422 includes a first waveguide portion 424 and a second waveguide portion 426 for directing incident electromagnetic radiation from the funnel element 102 towards the photosensitive element 110 .

[0113] Each one of the first waveguide sections 424 may be arranged to extend in a first direction, such as vertically, and may be further configured to be a single mode waveguide for electromagnetic radiation within a wavelength range to be detected by the detector 400. In the following, an exemplary discussion will be given in relation to a detector for visible light, and thus having a wavelength range in the visible part of the spectrum. However, other wavelength ranges, such as infrared or ultraviolet, are possible as well.

[0114] Each one of the first waveguide sections 424 may extend between the funnel element 102 and the photosensitive element 110 such that incident light is directed from the entrance end 104 of the funnel element 102 towards the photosensitive element.

[0115] The cross-section of the first waveguide section 424 taken along its length or perpendicularly may be substantially constant along the entire length of the waveguide section 424. However, it will be appreciated that other configurations may also be employed, such as, for example, a tapered shape in which the cross-section of the first waveguide section 424 decreases towards the photosensitive element 110 such that the angle between the waveguide sidewall and the cross-section of the waveguide is less than 90°, such as about 85°. The choice between straight sidewalls (i.e., constant cross-section) or tapered sidewalls may depend on the desired light transmission characteristics, which may be determined by the type of waveguide material, the wavelength of the electromagnetic radiation, and the desired coupling to the second waveguide section 426.

[0116] Each of the second waveguide sections 426 extends along a first direction parallel to the first waveguide section 424 and may be configured to outcouple light within a sub-range of the wavelength range of light in the first waveguide section 424. In this embodiment, the second waveguide sections 426 may be configured to, for example, couple out red, green or blue light such that those colors can be detected separately by the array 204 of photosensitive elements 110. In this manner, signal contrast may be achieved between the light transmitted through the first and second waveguide sections 424 and 426 by outcoupling sub-ranges corresponding to, for example, red, green or blue light.

[0117] The second waveguide section 426 may be sized with straight sidewalls or may be dimensioned by one or more tapered sidewalls, similar to the first waveguide section 424. The cross-sectional shape may be determined by the wavelengths to be outcoupled.

[0118] The second waveguide section 426 may be spaced slightly apart from the first waveguide section 424 such that they are separated by a vertical gap extending along the length of the waveguide sections 424, 426. However, other configurations are possible in which the first and second waveguide sections 424, 426 are disposed in contact with one another or are formed from a single piece.

[0119] The first and / or second waveguide sections 424, 426 and funnel element 102 may be at least partially surrounded or embedded in a material having a lower refractive index than the material of the waveguide sections. An example of such a material / surrounding may include silicon dioxide, as discussed above.

[0120] The first and second waveguide sections 424, 426 and the funnel element 102 may be formed from a material that includes silicon, such as, for example, silicon nitride.

[0121] Depending on the dimensions of the coupling region, i.e., the interface between the first and second waveguide sections 424, 426, light within a sub-range may be coupled into the second waveguide section 426 and directed towards the photosensitive element 110 located at the lower end portions of the first and second waveguide sections 424, 426, respectively.

[0122] It should further be appreciated that multiple second waveguide sections 426 may be used. Multiple second waveguide sections 426, i.e., color separation waveguides, may be disposed on one or more sides of the first waveguide section 424 to allow for individual detection of more specific wavelengths. By arranging the second waveguide sections 426 in an array and coupling light between adjacent ones of the second waveguide sections 426, it is possible to distinguish between multiple different wavelength sub-ranges.

[0123] Thus, each photosensitive element 110 may be configured to receive a particular sub-range of the wavelength range detected by detector 400. The signal from each photosensitive element 110 may thus represent the intensity of a particular sub-range of electromagnetic radiation.

[0124] 9, a detector according to any one of the previously described embodiments may be integrated into an image sensor 500. The image sensor 500 may thus include a detector 200 with a lens 226 for focusing incident electromagnetic radiation towards the array 202 of funnel elements 102 and the array 204 of photosensitive elements 110.

[0125] The image sensor 500 may further include additional optics for directing electromagnetic radiation or for controlling the electromagnetic radiation received by the detector 200 .

[0126] As described above, the array 204 of photosensitive elements 110 may be configured to capture image information in at least two image planes. The image sensor 500 may be configured to directly present the sensed signals of the array 204 of photosensitive elements 110 as images from multiple image planes, but may alternatively be configured to extract image information corresponding to a particular image plane from the image information captured by the array 204 of photosensitive elements 110 for display of the particular image plane.

[0127] It should be further appreciated that in some embodiments, the image information captured by the array 204 of photosensitive elements 110 may be analyzed directly without the need to form an image of the captured image information. For example, the captured image information may be used to determine the presence of an object at a particular depth corresponding to the electromagnetic radiation focused at a particular image plane. This may be used to quickly and accurately determine the distance to the object, which may be a very useful input in, for example, autonomous driving applications.

[0128] Referring now to FIG. 10, a method for detecting image information according to an embodiment is illustrated.

[0129] The method includes capturing 602 electromagnetic radiation with an array of funnel elements for propagating the electromagnetic radiation from a second plane toward a first plane, the second plane being defined by entrance ends of the funnel elements of the array, each funnel element having a size greater than half a wavelength of the electromagnetic radiation to capture focused electromagnetic radiation at the second plane.

[0130] The method further includes step 604 of detecting, in the array of photosensitive elements, electromagnetic radiation captured by the array of funnel elements to detect image information corresponding to the electromagnetic radiation focused at the second plane, and detecting electromagnetic radiation that has passed through the array of funnel elements to detect image information corresponding to the electromagnetic radiation focused at the first plane.

[0131] The electromagnetic radiation may also be captured at one or more additional planes defined by the entrance ends of the funnel elements of the further arrays to propagate focused electromagnetic radiation at the additional planes towards the array of photosensitive elements.

[0132] Therefore, thanks to this method, image information corresponding to focused electromagnetic radiation in at least a first plane and a second plane can be detected simultaneously, and two-dimensional image information as well as depth information can be detected simultaneously in the array of photosensitive elements.

[0133] In the above, the inventive concept has been primarily described with reference to a limited number of examples. However, as will be readily appreciated by those skilled in the art, examples other than those disclosed above are equally possible within the scope of the inventive concept as defined by the appended claims.

Claims

1. A detector for detecting electromagnetic radiation ranging from a first wavelength to a second wavelength, the first wavelength being the shortest wavelength in the range and the second wavelength being the longest wavelength in the range, the detector comprising: (200; 300; 400) an array (202) of funnel elements (102) for propagating electromagnetic radiation from a second plane towards a first plane, each of the funnel elements (102) including an entrance end (104) and an exit end (106), the entrance end (104) of the array (202) of funnel elements (102) defining a second plane, the entrance end (104) having a size greater than half a second wavelength of electromagnetic radiation in a medium from which the electromagnetic radiation enters a detector for capturing electromagnetic radiation focused at the second plane at the entrance end of the funnel element, propagating the electromagnetic radiation focused at the second plane within the funnel element to the exit end and allowing electromagnetic radiation focused at the first plane to pass through the funnel element and propagate to the first plane unaffected by the funnel element, and the exit end (106) having a size less than half the first wavelength of the electromagnetic radiation in the medium; an array (204) of photosensitive elements (110) for detecting electromagnetic radiation incident on the array (204) of photosensitive elements (110), each funnel element (102) being associated with a photosensitive element (110), the array (204) of photosensitive elements (110) defining a first plane, such that image information corresponding to the electromagnetic radiation focused in a second plane is detected by the array (204) of photosensitive elements (110), and the array (204) of photosensitive elements (110) configured to further capture image information corresponding to the electromagnetic radiation focused in the first plane.

2. 2. The detector of claim 1, wherein the funnel element (102) has at least one sidewall that is non-parallel to an extension of the funnel element (102) from the inlet end (104) to the outlet end (106).

3. 3. The detector of claim 1 or 2, further comprising a first array of waveguides (108), each waveguide (108) configured to direct electromagnetic radiation from the exit end (106) of the funnel element (102) to a photosensitive element (110).

4. 4. The detector of claim 3, wherein the waveguide includes a first waveguide portion (424) and a second waveguide portion (426), the first waveguide portion (424) configured to guide electromagnetic radiation within a wavelength range, the second waveguide portion (426) extending parallel to the first waveguide portion (424) and configured to selectively guide electromagnetic radiation within a sub-range of the wavelength range, and the second waveguide portion (426) coupled to the first waveguide portion (424) and configured to outcouple electromagnetic radiation from the first waveguide portion (424) within the sub-range of the wavelength range.

5. 5. The detector of claim 1, wherein the array of funnel elements is a first array (202) of funnel elements (102), and the detector (200; 300; 400) further comprises a second array (210; 310; 410) of funnel elements (102) for propagating electromagnetic radiation from the third plane towards the first plane, each of the funnel elements (102) of the second array (210; 310; 410) comprising an entrance end and an exit end, the entrance end of the second array (210; 310; 410) of funnel elements (102) defining the third plane, the entrance end having a size greater than half a second wavelength of the electromagnetic radiation in the medium to capture the electromagnetic radiation focused at the third plane, and the exit end having a size smaller than half the first wavelength of the electromagnetic radiation in the medium.

6. 6. The detector of claim 5, further comprising an array (216) of intermediate waveguides (222), each intermediate waveguide (222) configured to direct electromagnetic radiation from an exit end of a funnel element (102) of the second array (210) to an entrance end of a funnel element (102) of the first array (202).

7. 6. The detector of claim 5, further comprising a second array (316) of waveguides (322), each waveguide (322) of the second array (316) configured to direct electromagnetic radiation from an exit end of a funnel element (102) of the second array (310; 410) to a photosensitive element (110).

8. The detector of any one of claims 1 to 7, wherein the array (204) of photosensitive elements (110) comprises different sets of photosensitive elements (110) for capturing image information corresponding to electromagnetic radiation focused at different planes.

9. A detector according to any one of the preceding claims, wherein the funnel element (102) is formed from a high refractive index material and surrounded by a low refractive index material.

10. The detector of any one of claims 1 to 9, wherein the photosensitive element (110) comprises a photoactive layer (114) for generating a signal corresponding to an amount of incident electromagnetic radiation on the photoactive layer (114).

11. The detector of claim 10, wherein the photosensitive element (110) further comprises an interconnect layer (116) for transmitting signals from the photoactive layer (114) to a semiconductor circuit.

12. The detector (200; 300; 400) according to any one of the preceding claims, comprising a single lens (226) for focusing incident electromagnetic radiation towards the array (202) of funnel elements (102) and the array (204) of photosensitive elements (110).

13. A detector according to any preceding claim, further comprising a filter for extracting image information corresponding to electromagnetic radiation focused at a particular plane.

14. 14. An image sensor comprising a detector (200; 300; 400) according to any one of claims 1 to 13, wherein the image sensor (500) is configured to detect three-dimensional image information based on simultaneously capturing image information in at least two image planes.

15. 1. A method for detecting image information, comprising: capturing (602) electromagnetic radiation ranging from a first wavelength to a second wavelength, the first wavelength being the shortest wavelength in the range and the second wavelength being the longest wavelength in the range, the electromagnetic radiation being captured in an array (202) of funnel elements (102) for propagating the electromagnetic radiation from the second plane towards the first plane, an entrance end (104) of each funnel element (102) having a size greater than half the second wavelength of the electromagnetic radiation in the medium from which the electromagnetic radiation enters a detector for capturing the electromagnetic radiation focused at the second plane at the entrance end of the funnel element, propagating the electromagnetic radiation focused at the second plane within the funnel element to an exit end of the funnel element, and allowing the electromagnetic radiation focused at the first plane to pass through the funnel element and propagate to the first plane without being affected by the funnel element; and detecting (604) electromagnetic radiation that has passed through the array (202) of funnel elements (102) to detect image information corresponding to the electromagnetic radiation focused at the first plane, while detecting electromagnetic radiation captured by the array (202) of funnel elements (102) at the array (204) of photosensitive elements (110) to detect image information corresponding to the electromagnetic radiation focused at the second plane.

Images