SINGLE PHOTON DETECTOR DEVICE FOR DETECTING AN OPTICAL SIGNAL

Description

[0001] The invention relates to a single-photon detector device for detecting an optical signal comprising at least one optical waveguide and one nanowire.

[0002] Waveguide-integrated superconducting photon detectors, and in particular their subtype superconducting nanowire single-photon detectors (SNSPDs), highly efficiently detect broadband light propagating in a waveguide on which they are integrated. SNSPDs feature a nanowire as the actual detector element, which is superconducting at sufficiently low temperatures.

[0003] In the case of SNSPDs known in the state of the art, as described in Figure 1As shown, the nanowire 1 extends either in a U-shape or a W-shape along an optical axis 2 of the waveguide 3. Due to the extension of the nanowire 1 along the optical axis 2, the absorption of the light guided in the waveguide 3 by the nanowire 1 depends on its length, so that the absorption of the nanowire 1 and thus the efficiency of the detector can be determined by the length of the nanowire 1. However, these shapes have the disadvantage that the efficiency of the SNSPD varies depending on the direction 4a, 4b from which the light is guided in the waveguide 3.

[0004] In addition, SNSPDs with I-shaped nanowires 1 extending perpendicular to the optical axis 2 are known in the prior art. However, due to their extension perpendicular to the optical axis 2, these nanowires exhibit only very low absorption, so that these SNSPDs do not allow for highly efficient light detection.

[0005] US 2020 / 333179 A1, US 2019 / 189816 A1, and GB 2588330 A each disclose SNSPDs and methods for their fabrication. Further prior art is disclosed in JAN PHILIPP HÖPKER ET AL: "Integrated superconducting nanowire single-photon detectors on titanium in-diffused lithium niobate waveguides," ARXIV.ORG, CORNELL UNIVERSITY LIBRARY, April 26, 2021.

[0006] Based on this, the object of the invention is to provide a single-photon detector whose difference in detection efficiency for light from different propagation directions is reduced. In particular, the object of the invention is to provide a single-photon detector that detects light from different propagation directions with essentially equivalent high efficiency.

[0007] This problem is solved by the features of the independent patent claim. Preferred developments can be found in the subclaims.

[0008] According to the invention, a single-photon detector device for detecting an optical signal is provided, comprising at least one optical waveguide and one nanowire, wherein the single-photon detector device is an SNSPD device, wherein the at least one waveguide is designed to guide the optical signal along an optical axis in two mutually opposite directions, wherein the nanowire is applied to the optical waveguide or is integrated into the waveguide, or is arranged in the optical near field of the waveguide not more than 1 µm away from the optical waveguide, wherein the nanowire is at least partially curved within a region defined by the at least one waveguide, and wherein the nanowire is shaped such that the nanowire is curved within the region defined by the at least one waveguide a) is substantially mirror-symmetrical with respect to a plane perpendicular to the optical axis, or b) is substantially point-symmetrical with respect to a point within the region defined by the at least one waveguide, wherein, within the region defined by the waveguide, deviations from the symmetry of up to ± 5% in any spatial direction and / or of up to ± 10 µm along the optical axis are possible, characterized in that the single-photon detector device comprises a coupler, wherein the coupler is connected to two ends of the at least one waveguide and is designed such that an optical signal can be coupled into different ends of the at least one waveguide depending on its polarization, and wherein the nanowire is arranged in a region between the two ends of the at least one waveguide.

[0009] The core of the invention is to form the nanowire within the region defined by the waveguide in a specific shape having at least one curvature and a substantially mirror-symmetric or substantially point-symmetric configuration. This enables, on the one hand, the single-photon detector device to detect the optical signal guided in the waveguide with high efficiency and, on the other hand, to greatly reduce the differences in the efficiency with which the single-photon detector device detects the optical signal depending on the propagation direction of the optical signal. Particularly preferably, the single-photon detector device can detect the optical signal with substantially the same efficiency regardless of its propagation direction.In other words, the single-photon detector device does not have a preferred direction in which the optical signal is detected with higher efficiency, as is the case in the prior art.

[0010] The waveguide of the single-photon detector device is designed such that the optical signal can propagate along the optical axis of the waveguide. It is provided that the optical signal can propagate in two opposite directions along the optical axis. The optical waveguide is preferably a planar optical waveguide structure used in integrated optics. The nanowire can in principle be applied to the optical waveguide, integrated into the waveguide, or arranged in the optical near field of the waveguide, preferably no more than 1 µm from the optical waveguide. Particularly preferably, the nanowire is integrated into the waveguide structure directly during production of the waveguide, which is formed on a chip.

[0011] The nanowire has a specific shape within the region defined by the at least one waveguide. For the purposes of the invention, the "region defined by the waveguide" refers to a spatial region whose dimensions correspond to the dimensions of the waveguide. For example, the nanowire can extend transversely to the optical axis of the waveguide and be longer than the width of the waveguide such that the nanowire protrudes beyond the sides of the waveguide. In this example, a portion of the nanowire, namely that which crosses the waveguide, lies within the region defined by the waveguide. The portion of the nanowire that protrudes beyond the sides of the waveguide lies outside the region defined by the waveguide.

[0012] The portion of the nanowire that lies outside the region defined by the waveguide can take any shape. The portion of the nanowire that lies within the region defined by the waveguide is at least partially curved. This means that the nanowire exhibits at least some curvature in this region. This allows the nanowire to be guided at least partially parallel to the optical axis of the waveguide, so that the single-photon detector device has very high efficiency and can detect even very small optical signals—preferably in the range of a single photon or a few photons.

[0013] Furthermore, it is provided that the nanowire within the region defined by the waveguide a) is substantially mirror-symmetrical with respect to the plane perpendicular to the optical axis, or b) that the nanowire is substantially point-symmetrical with respect to the point within the region defined by the waveguide, wherein deviations from the symmetry of up to ± 5% in each spatial direction and / or of up to ± 10 µm along the optical axis are possible within the region defined by the waveguide.

[0014] With reference to a), the shape of the nanowire within the area defined by the waveguide is such that a mirror plane perpendicular to the optical axis of the waveguide exists, which maps the shape of the nanowire within the area defined by the waveguide onto itself by reflection at the mirror plane. However, deviations from the mirror symmetry are possible within two tolerance ranges, namely by up to ± 5% in any spatial direction and / or by up to ± 10 µm along the optical axis. In other words, with regard to the first tolerance range, this means that any point on the nanowire can deviate by up to ± 5% from the point specified by the mirror symmetry in any spatial direction. The percentage refers to the distance of the point perpendicular to the mirror plane.For example, if a point on the nanowire is 100 µm away from the mirror plane due to mirror symmetry, the first tolerance range allows the corresponding point to be located in a sphere with a diameter of 5 µm (equivalent to 5% of 100 µm) around the point specified by the mirror symmetry. Independent of this first tolerance range, any point on the nanowire can deviate by up to ± 10 µm from the point specified by the mirror symmetry along the optical axis of the waveguide. For example, if a point on the nanowire is 150 µm away from the mirror plane due to mirror symmetry, the second tolerance range allows the corresponding point to be located within a range of 140 µm to 160 µm from the mirror plane.Within these deviations from mirror symmetry, it is still possible for the single-photon detector device to detect the optical signal with equal efficiency regardless of its propagation direction.

[0015] With respect to b), the shape of the nanowire within the region defined by the waveguide is such that a symmetry point exists within the region defined by the waveguide, which maps the shape of the nanowire within the region defined by the waveguide onto itself by reflection at the symmetry point.

[0016] Here too, deviations from point symmetry are possible within two tolerance ranges, namely by up to ± 5% in any spatial direction and / or up to ± 10 µm along the optical axis. In other words, with regard to the first tolerance range, this means that any point on the nanowire can deviate by up to ± 5% from the point specified by the point reflection, in any spatial direction. The percentage refers to the distance of the point to the point of symmetry. For example, if a point on the nanowire is 100 µm away from the point of symmetry due to point symmetry, the first tolerance range allows the corresponding point to be located in a sphere with a diameter of 5 µm (equivalent to 5% of 100 µm) around the point specified by the point symmetry.Independent of this first tolerance range, any point on the nanowire can deviate by up to ± 10 µm from the point along the optical axis of the waveguide specified by the point symmetry. For example, if a point on the nanowire is 150 µm away from the point of symmetry due to point symmetry, the second tolerance range allows the corresponding point to be within a range of ± 10 µm along the optical axis around the point specified by the point symmetry. Within these deviations from point symmetry, it is still possible for the single-photon detector device to detect the optical signal with equal efficiency regardless of its propagation direction.

[0017] Both embodiments a) and b) allow the differences in efficiency with which the single-photon detector device detects the optical signal depending on its propagation direction in the waveguide to be significantly reduced. Particularly preferably, the detection efficiency is independent of the propagation direction of the optical signal in the waveguide.

[0018] With regard to feature b), it is preferably provided that the point, i.e. the point of symmetry, is equidistant from two sides of the region defined by the waveguide. In other words, it is preferably provided that the point of symmetry is located centrally in the region defined by the waveguide. According to a preferred development of the invention, it is provided that the nanowire is formed according to feature a) and that two ends of the nanowire are outside the region defined by the waveguide on the same side of the at least one waveguide. Preferably, the nanowire therefore does not end within the region defined by the waveguide, but rather its two ends are located outside the region defined by the waveguide. Preferably, the two ends of the nanowire are on the same side of the waveguide.This makes it particularly easy to connect the two ends of the nanowire to an electrode each.

[0019] In this context, according to a further preferred development, it is provided that the nanowire is shaped according to feature b) and that two ends of the nanowire are located outside the region defined by the waveguide, each on opposite sides of the at least one waveguide. Even if the nanowire is designed according to feature b), it is preferably provided that the ends of the nanowire are not located within the region defined by the waveguide, but outside it. Furthermore, it is preferably provided that the ends of the nanowire are on opposite sides of the waveguide. In this case, it is preferably provided that the two ends of the nanowire are essentially at the same location with respect to the optical axis. This simplifies the attachment of electrodes and thus the manufacture of the single-photon detector device.

[0020] Within the region defined by the waveguide, the nanowire can, in principle, have any shape with at least one curvature, as long as the shape exhibits either the described mirror symmetry or point symmetry. In this context, it is preferably provided that the nanowire has a meandering shape, an S-shape, and / or an oval shape within the region defined by the at least one waveguide. The S-shape is an example of a point-symmetric shape, with the ends of the nanowire being on different sides of the waveguide. The oval shape is an example of a mirror-symmetric shape, with the ends of the nanowire being on the same side of the waveguide.In the present case, an oval shape does not mean that the two ends of the nanowire meet at one point within the area defined by the waveguide and form a closed oval, but rather that two end areas of the nanowire are spatially so close to each other within the area defined by the waveguide that the nanowire's shape covers at least 75% of the circumference of a closed oval.

[0021] With regard to the tolerance range and the S-shape, it can be provided, for example, that a first curvature of the S-shape, relative to a reference axis perpendicular to the optical axis and passing through the point of symmetry, is 10 µm further away from this reference axis than a second curvature of the S-shape corresponding to this first curvature due to the point symmetry. With regard to the tolerance range and the oval shape, it can be provided, for example, that a first curvature of the oval shape is 10 µm closer to the mirror plane than the second curvature of the oval shape corresponding to the first curvature due to the mirror symmetry.

[0022] In principle, it is possible for the single-photon detector device to comprise exactly one waveguide and exactly one nanowire. Alternatively, it is possible for the single-photon detector device to comprise a plurality of waveguides and exactly one nanowire. In this context, according to a preferred development, the single-photon detector device comprises a plurality of intersecting waveguides, wherein the plurality of waveguides is configured to guide the optical signal along a respective optical axis in two mutually opposite directions. It can therefore be provided that exactly one nanowire is used for the plurality of intersecting waveguides.Due to the plurality of intersecting waveguides, each designed to guide the optical signal along its optical axis in two opposite directions, the single-photon detector device thus has more than two propagation directions. The nanowire is preferably designed such that the optical signal can be detected with equal efficiency in all propagation directions.

[0023] Furthermore, in this context, according to a preferred development, it is provided that the nanowire is curved within the region defined by each waveguide, and that the nanowire is shaped such that the nanowire is mirror-symmetrical within the region defined by each waveguide with respect to a plane perpendicular to the optical axis of the respective waveguide, wherein deviations from symmetry of up to ± 5% in each spatial direction and / or of up to ± 10 µm along the respective optical axis are possible within the region defined by each waveguide. In other words, the nanowire is curved several times over its entire length and has mirror symmetry within each region defined by a waveguide.

[0024] With regard to the ends of the nanowire, in connection with the plurality of intersecting waveguides, according to a preferred embodiment of the invention, two ends of the nanowire are each located on the same side of each waveguide of the plurality of waveguides. Thus, the two ends are preferably always located on the same side of a waveguide, and this applies to all waveguides.

[0025] Furthermore, it is preferably provided that the nanowire is shaped such that the nanowire is essentially mirror-symmetrical with respect to a global mirror plane within all regions defined by the respective waveguides, whereby deviations from the global mirror symmetry of up to ± 5% in any spatial direction and / or of up to ± 10 µm along the respective optical axis of the waveguide are possible. Thus, it is preferably provided not only that the nanowire exhibits mirror symmetry only locally in the region defined by a waveguide, but also that the nanowire exhibits mirror symmetry in its shape, which the nanowire has within all regions defined by the waveguides.

[0026] In connection with the intersecting waveguides, according to a preferred embodiment of the invention, the majority of the waveguides intersect in a common region. For example, three intersecting waveguides form the shape of a star. In this way, optical signals from a variety of propagation directions can be detected with a nanowire.

[0027] A challenge for single-photon detector devices comprising at least one waveguide and one nanowire is that the optical signal must be coupled into the waveguide. The couplers used to couple the optical signal typically exhibit different coupling efficiencies for differently polarized portions of the optical signal. Accordingly, in order to couple the highest possible portion of the optical signal into the waveguide, it is necessary to control the polarization of the optical signal before coupling it into the waveguide, which requires additional optical components.In connection with the omission of the control of the polarization of the optical signal before coupling it into the waveguide, the invention provides that the single-photon detector device comprises a coupler, wherein the coupler is connected to two ends of the at least one waveguide and is configured such that the optical signal can be coupled into different ends of the at least one waveguide depending on its polarization, and wherein the nanowire is arranged in a region between the two ends of the at least one waveguide. Because the single-photon detector device can detect the optical signal with equal efficiency regardless of its propagation direction, a polarization-independent single-photon detector device can be provided with a coupler that couples the optical signal into the different ends of the same waveguide depending on its polarization.This has the advantage that, for applications with a high number of channels, the required number of detectors can be reduced while maintaining the same efficiency for both polarization directions of the optical signal, since only one polarization-independent single-photon detector device needs to be used for both polarization directions. Preferably, deviations from mirror symmetry or deviations from point symmetry within the described tolerance ranges can be used in the nanowire to compensate for different absorptions of the nanowire with respect to the two polarization directions, thus detecting the optical signal with the same efficiency regardless of its propagation direction.

[0028] According to the invention, the nanowire is applied to the optical waveguide or integrated into the waveguide, or is arranged in the optical near field of the waveguide no more than 1 µm away from the optical waveguide. Preferably, the single-photon detector device is therefore a single-photon detector device that can be realized using common manufacturing methods from the CMOS industry (complementary metal-oxide semiconductor; semiconductor process for the production of integrated digital and / or analog semiconductor components). Furthermore, it is preferably provided that the nanowire has a substantially rectangular cross-section, wherein the thickness of the nanowire is such that a superconducting current can be conducted through the nanowire. The thickness of the nanowire is preferably between 3 nm and 20 nm.More preferably, the width of the nanowire is between 10 nm and 2000 nm, preferably between 20 nm and 500 nm. The thickness of the nanowire can be influenced during the manufacturing process by the thickness of the deposited superconducting layer. After deposition, the layer can be structured, for example, by electron beam lithography and plasma-assisted etching processes, whereby the width of the nanowire can be determined. Furthermore, it is further preferred that the length of the nanowire—measured from one end of the nanowire to the other end of the nanowire—is at least five times greater than the width of the nanowire.

[0029] With regard to the material of the nanowire, it is preferably provided that the nanowires comprise at least one of the materials from the group comprising Nb, NbN, NbTi, NbTiN, Nb3Ge, Nb3Sn, SmFeAsO1-xFx, CeOFeAs, MgB2, WxSi1-xMoRe, MoSi, TaN, graphene, iron-containing high-temperature superconductors (iron pnictides), and high-temperature superconductors with copper oxide, in particular YBCO and / or BSCCO. The nanowire can consist of one of the materials or of several materials in any combination. Alternatively or additionally, it can also consist of other superconducting materials.

[0030] The invention is explained below by way of example with reference to the drawing using preferred embodiments.

[0031] The drawing shows Fig. 1 shows schematic representations of single-photon detector devices as known in the art, Fig. 2 shows a schematic representation of a single-photon detector device, Fig. 3 shows a schematic representation of a single-photon detector device, Fig. 4 shows a schematic representation of a single-photon detector device, Fig. 5 shows a schematic representation of a single-photon detector device with a coupler, according to a preferred embodiment of the invention, and Fig. 6 shows a schematic representation of a single-photon detector device.

[0032] Figure 2 and 3show schematic representations of two single-photon detector devices 10 for detecting an optical signal. The single-photon detector device 10 comprises an optical waveguide 12. The waveguide 12 is configured to guide the optical signal along an optical axis 14 in two opposing directions 16a, 16b. Furthermore, the single-photon detector device 10 comprises a nanowire 18.

[0033] In both the Figure 2 and 3 In the single-photon detector devices 10 shown, the nanowire 18 is at least partially curved within a region 20 defined by the waveguide 12. As shown in Figure 2 and 3 As can be seen, the nanowire 18 in both single-photon detector devices 10 has four bends 22a, 22b, 22c, 22d within the region 20 defined by the waveguide 12.

[0034] In addition, the nanowire 18 is in the Figure 2The single-photon detector device 10 shown is shaped such that the nanowire 18 within the region 20 defined by the waveguide 12 is mirror-symmetrical with respect to a plane 24 perpendicular to the optical axis 14. In other words, the mirror plane 24 maps the shape of the nanowire 18 within the region 20 onto itself. In the present case, the nanowire 18 has an oval shape within the region 20.

[0035] In the Figure 3 In the single-photon detector device 10 shown, the nanowire 18 is shaped such that the nanowire 18 is point-symmetric within the region 20 defined by the waveguide 12 with respect to a point 26 within the region 20 defined by the waveguide 12. In other words, the point of symmetry 26 maps the shape of the nanowire 18 within the region 20 onto itself. In this case, the nanowire 18 meanders within the region 20 and has the shape of an S.

[0036] In both single-photon detector devices 10 shown, two ends 28a, 28b of the nanowire 18 are outside the area 20 defined by the waveguide 12. In the single-photon detector device 10 in Figure 2 the two ends 28a, 28b are on the same side of the waveguide 12. In the single photon detector device 10 in Figure 3 the two ends 28a, 28b are each located on opposite sides of the waveguide 12, wherein, with respect to the optical axis 14, the two ends 28a, 28b are essentially at the same location.

[0037] Figure 4shows a further single-photon detector device 10. In this single-photon detector device 10, the single-photon detector device 10 has a plurality of waveguides 12a, 12b, 12c -- in the present case three. The three waveguides 12a, 12b, 12c intersect in an intersection region 30. Each waveguide 12a, 12b, 12c is designed such that it can propagate the optical signal along its optical axis 14a, 14b, 14c (which, for the sake of clarity, is only shown for waveguide 12b) in the two opposite directions 16a, 16b, so that the single-photon detector device 10 has a total of six propagation directions, namely the directions 16aa and 16ba for waveguide 12a, the directions 16ab and 16bb for waveguide 12b, and the directions 16ac and 16bc for waveguide 12c. In addition, each of the waveguides 12a, 12b, 12c defines a region 20a, 20b, 20c (which is shown only for the waveguide 12b for the sake of clarity).

[0038] The nanowire 18 is formed in the present case such that the nanowire 18 is curved within each of the regions 20a, 20b, 20c, and that the nanowire 18 is mirror-symmetric within each of the regions 20a, 20b, 20c with respect to a plane 24a, 24b, 24c perpendicular to the respective optical axis 14a, 14b, 14c. Furthermore, the nanowire 18 in the present example is formed such that the nanowire 18 is mirror-symmetric within all regions 20a, 20b, 20c with respect to a global mirror plane 32, which in the present case coincides with the mirror plane 24b. Regarding the ends 28a, 28b of the nanowire 18, Figure 4 that the two ends 28a, 28b are each on the same side of each waveguide 12a, 12b, 12c.

[0039] Figure 5shows a preferred embodiment of the single-photon detector device 10 according to the invention. In this embodiment, the single-photon detector device 10 comprises a coupler 34. The coupler 34 is designed such that the optical signal 36, which comprises two differently polarized components 38a, 38b, can be coupled into different ends 40a, 40b of the waveguide 12 depending on the polarization direction. Accordingly, the coupler 34 is connected to the two ends 40a, 40b of the waveguide 12. The nanowire 18 (itself not in Figure 5 shown) is located in a region 42 between the two ends 40a, 40b of the waveguide 12. In addition, Figure 5a glass fiber 44 is shown, which guides the optical signal 36 before it is coupled into the waveguide 12 by means of the coupler 34. Because the single-photon detector device 10 can detect the portions 38a, 38b of the optical signal 36 propagating in opposite directions 16a, 16b with the same efficiency, regardless of the propagation direction 16a, 16b, Figure 5 a polarization-independent single-photon detector device 10.

[0040] Figure 6 shows a schematic representation of another single-photon detector device 10 for detecting an optical signal. The single-photon detector device 10 is as in Figure 2However, the nanowire 18 has a deviation from mirror symmetry within a tolerance range. The nanowire 18 is at least partially curved in the region 20 defined by the waveguide 12 and is designed essentially mirror-symmetrically. Figure 6 It can be clearly seen that the right curvature 22b of the nanowire 18 is not at the curvature location 46 corresponding to the location of the left curvature 22a via the mirror symmetry, but is offset from it at the curvature location 48. The two curvature locations 46, 48 are spaced apart from each other by 10 µm measured along the optical axis 14, which is symbolized by the arrow 50. List of reference symbols

[0041] 1Nanowire (state of the art) 2Optical axis (state of the art) 3Waveguide (state of the art) 4a, 4bPropagation directions (state of the art) 10 Single-photon detector device 12 Waveguide 14 Optical axis 16a, 16b Propagation directions 16aa, 16ba Propagation direction of waveguide 12a 16ab, 16bb Propagation direction of waveguide 12b 16ac, 16bc Propagation direction of waveguide 12c 18 Nanowire 20 Region defined by the waveguide 22 Curvature 24 Mirror plane 26 Point of symmetry 28a, 28b Ends of the nanowire 30 Crossing region 32 Global mirror plane 34 Coupler 36 Optical signal 38a, 38b Polarized portions of the optical signal 40a, 40b Ends of the waveguide 42 Region on the waveguide 44 Optical fiber 46 Location of curvature determined by mirror symmetry 48Curvature location 50Distance between curvature location 46 and curvature location 48

Claims

1. Single photon detector device (10) for detecting an optical signal (36), comprising at least one optical waveguide (12) with two ends (40a, 40b) and a nanowire (18), wherein the single photon detector device (10) is a SNSPD device, wherein the at least one waveguide (12) is designed to guide the optical signal (36) along an optical axis (14) in two mutually opposite directions (16a, 16b), wherein the nanowire (18) is applied on the optical waveguide (12) or is integrated into the waveguide (12) or is arranged in the optical near field of the waveguide (12) not more than 1 µm away from the optical waveguide (12), wherein the nanowire (18) is at least partly curved within a region (20) defined by the at least one waveguide (12), and wherein the nanowire (18) is shaped in such a way that within the region (20) defined by the at least one waveguide (12) the nanowire (18) a) is substantially mirror-symmetrical relative to a plane (24) perpendicular to the optical axis (14), or b) is substantially point-symmetrical relative to a point (26) within the region (20) defined by the at least one waveguide (12), wherein within the region (20) defined by the waveguide (12) deviations (50) from symmetry of up to ± 5% in each spatial direction and / or of up to ± 10 µm along the optical axis (14) are possible characterized in that the single photon detector device (10) comprises a coupler (34), wherein the coupler (34) is connected to the two ends (40a, 40b) of the at least one waveguide (12) and is designed in such a way that an optical signal (36) can be coupled into different ends (40a, 40b) of the at least one waveguide (12) depending on its polarization (38a, 38b), and wherein the nanowire (18) is arranged in a region (42) between the two ends (40a, 40b) of the at least one waveguide (12).

2. Single photon detector device (10) as claimed in claim 1, wherein the nanowire (18) is shaped according to feature a) and wherein two ends (28a, 28b) of the nanowire (18) outside the region (20) defined by the waveguide (12) are on the same side of the at least one waveguide (12).

3. Single photon detector device (10) as claimed in claim 1, wherein the nanowire (18) is shaped according to feature b) and wherein two ends (28a, 28b) of the nanowire (18) outside the region (20) defined by the waveguide (12) are each on mutually opposite sides of the at least one waveguide (12).

4. Single photon detector device (10) as claimed in any of the preceding claims, wherein within the region (20) defined by the at least one waveguide (12) the nanowire (18) has a meandering shape, an S-shape and / or an oval shape.