strain gauges

Description

Technical field

[0001] This description relates generally to integrated circuits, and more particularly to integrated circuits implementing a strain gauge. Prior art

[0002] Known integrated circuits comprise a piezoresistive or photonic strain gauge for measuring a strain of an element, the strain gauge then being attached to and in contact with the element whose strain is being measured so that a strain of this element causes a corresponding strain of the gauge.

[0003] Known photonic integrated circuits propose to measure a displacement between a first element and a second element movable relative to each other. These circuits comprise an opto-mechanical strain gauge comprising an optical resonator fixed to the first element, such that a displacement of the two elements relative to each other causes a variation (or deformation) of a mechanical gap between the optical resonator and the second element, or a variation (or deformation) of an optical gap between the resonator and a waveguide fixed to the second element. The variation of the mechanical gap causes a modification of the effective optical index of the resonator resulting from the modification of the gap separating the first and second elements, and therefore a corresponding and measurable variation of its resonance wavelength.The variation of the optical gap, where the waveguide is optically coupled to the optical resonator, results in a corresponding and measurable change in the optical coupling between the waveguide and the resonator.

[0004] Compared to known piezoresistive strain gauges, known optomechanical strain gauges make it possible to do without the electrical connections required for polarization and strain measurement of the piezoresistive gauge.

[0005] However, known optomechanical strain gauges, particularly those for measuring relative displacement of two elements relative to each other, have other drawbacks. For example, the production of the mechanical gap may require lithography means that are not readily available to many foundries. The prior art documents relevant to the invention are as follows: AHMED SALIM ET AL: “Inkjet printed kirigami inspired split ring resonator for disposable, low cost strain sensor applications”, SMART MATERIALS AND STRUCTURES, IOP PUBLISHING LTD, BRISTOL, GB, vol. 29, no. 1, November 29, 2019 (2019-11-29), page 15016 and US 2016 / 246000 A1 (DURAFFOURG LAURENT [FR] ET AL) August 25, 2016 (2016-08-25).

[0006] It would be desirable to have a photonic device or photonic integrated circuit comprising an optomechanical strain gauge that overcomes all or part of the drawbacks of known optomechanical strain gauges. Summary of the invention

[0007] One embodiment overcomes all or part of the drawbacks of known devices comprising a known opto-mechanical strain gauge for measuring a relative displacement between two elements moving relative to each other.

[0008] One embodiment provides a device comprising: a substrate; a first layer resting on the substrate, the first layer comprising a first portion and a second portion movable relative to each other; a ring optical resonator defined in a second layer, the resonator comprising a first portion attached to a first anchor pad connected to the first portion of the first layer and a second portion attached to a second anchor pad connected to the second portion of the first layer.

[0009] According to one embodiment, the first and second anchoring pads are arranged inside the resonator.

[0010] According to one embodiment, the first and second portions of the resonator each have a semicircular shape.

[0011] According to one embodiment: the first pad has a half-disc shape having its center coincident with the center of the first portion of the resonator and its curved part facing the first portion of the resonator; and / or the second pad has a half-disc shape having its center coincident with the center of the second portion of the resonator and its curved part facing the second portion of the resonator.

[0012] According to one embodiment: the first portion of the resonator is attached to the first pad by first beams defined in the second layer, each of the first beams having a first end connected to the resonator and a second end connected to the first pad; and / or the second portion of the resonator is attached to the second pad by second beams defined in the second layer, each of the second beams having a first end connected to the resonator and a second end connected to the second pad.

[0013] According to one embodiment, each of the first and second beams has a larger cross-section on the side of its second end than on the side of its first end.

[0014] According to one embodiment: the first portion of the resonator is fixed to the first pad by a first continuous portion of the second layer, the assembly of the first portion of the resonator, the first portion of the second layer and the first pad having a half-disc shape; and / or the second portion of the resonator is fixed to the second pad by a second continuous portion of the second layer, the assembly of the second portion of the resonator, the second portion of the second layer and the second pad having a half-disc shape.

[0015] According to one embodiment: the first portion of the resonator is attached to the first pad by a first portion of the second layer, the assembly of the first portion of the resonator, the first portion of the second layer and the first pad having a half-disc shape, and the first portion of the second layer comprises through openings configured to promote a single optical propagation mode in the first portion of the resonator; and / or the second portion of the resonator is attached to the second pad by a second portion of the second layer, the assembly of the second portion of the resonator, the second portion of the second layer and the second pad having a half-disc shape, and the second portion of the second layer comprises through openings configured to promote a single optical propagation mode in the second portion of the resonator.

[0016] According to one embodiment, the resonator comprises a third portion connecting the first portion of the resonator to the second portion of the resonator, and another third portion connecting the second portion of the resonator to the first portion of the resonator, the assembly of the first, second and third portions forming the ring of the resonator.

[0017] According to one embodiment, each of the first and second portions of the resonator has a cross-section configured to allow multi-mode guiding of the light, and each of the third portions has a central portion having a cross-section configured to allow single-mode guiding of the light.

[0018] According to one embodiment, the first and second parts of the first layer are movable relative to each other in a first direction parallel to the substrate.

[0019] According to one embodiment, the second layer is disposed between the substrate and the first layer, the first and second portions of the first layer being suspended above the substrate.

[0020] According to one embodiment, the device further comprises a waveguide defined in the second layer and having a portion optically coupled to the resonator, said portion of the waveguide being either optically coupled to the first portion of the resonator and attached to the first portion of the first layer, or optically coupled to the second portion of the resonator and attached to the second portion of the first layer.

[0021] According to one embodiment: the first portion of the first layer is fixed relative to the substrate; the first layer further comprises a third portion suspended above the substrate and movable relative to the substrate in a plane parallel to the substrate; and the device comprises a lever arm, for example at least partly defined in the first layer, configured so that a movement of the third portion relative to the substrate in said plane parallel to the substrate causes a corresponding movement of the second portion of the first layer relative to the first portion of the first layer in said plane parallel to the substrate.

[0022] According to one embodiment: the first part of the first layer is fixed relative to the substrate; the first layer further comprises a third part suspended above the substrate and rotatable about an axis parallel to the substrate; and the device comprises a lever arm, for example partly defined in the first layer, configured so that a rotation of the third part about said axis causes a corresponding displacement of the second part of the first layer relative to the first part of the first layer in a plane parallel to the substrate. Brief description of the drawings

[0023] These and other features and advantages will be set forth in detail in the following description of particular embodiments given without limitation in relation to the attached figures, among which: there figure 1 represents, by a schematic top view, an example of an embodiment of a device; the figure 2represents a schematic sectional view taken in plane AA of the figure 1 ; there figure 3 represents a schematic sectional view taken in plane BB of the figure 1 ; there figure 4 represents a schematic sectional view taken in the plane CC of the figure 1 ; there Figure 5 represents a schematic sectional view taken in the DD plane of the figure 1 ; there figure 6 represents, by a partial and schematic top view, an alternative embodiment of a part of the device of the figures 1 to 5 ; there figure 7 represents, by a partial and schematic top view, another variant embodiment of a part of the device of the figures 1 to 5 ; there figure 8 represents, by a partial and schematic top view, yet another variant embodiment of a part of the device of the figures 1 to 5 ; there figure 9represents, by a partial and schematic top view, yet another variant embodiment of a part of the device of the figures 1 to 5 ; and the figure 10 represents, by a schematic top view, another example of an embodiment of the device of the figures 1 to 5 . Description of the embodiments

[0024] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been shown and are detailed. In particular, the methods for manufacturing the photonic circuits described here have not been detailed, the manufacturing of the embodiments and variants of these photonic circuits from usual steps of manufacturing known photonic circuits being within the scope of the person skilled in the art from the description below.

[0025] Unless otherwise specified, when referring to two elements mechanically connected to each other, this means directly in contact without intermediate elements, and when referring to two elements mechanically connected or coupled to each other, this means that these two elements can be connected or linked by means of one or more other elements.

[0026] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0027] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0028] There is provided herein a device comprising a substrate, a first layer indirectly resting on the substrate and a ring optical resonator defined in a second layer, wherein the first layer comprises a first portion and a second portion configured to be movable relative to each other, for example in a direction parallel to the substrate, and wherein the resonator has a first portion attached to the first portion of the first layer and a second portion attached to the second portion of the second layer.

[0029] Thus, when the first and second parts of the first layer move relative to each other, for example in the aforementioned direction, portions of the resonator that connect the first and second portions of the resonator to form the resonator ring deform, for example compress or expand in the aforementioned direction. These deformations of the ring cause a corresponding change in its resonance wavelength. By measuring the variation in the resonance wavelength of the ring, it is possible to know, and therefore measure, the relative displacement of the first and second parts of the first layer relative to each other.

[0030] Unless otherwise specified, when referring to an element being anchored, fixed, attached, or hooked to the first layer, this means that this element is mechanically coupled to the first layer, and that this element is mechanically coupled to the substrate via the first layer. For example, put another way, this means that the mechanical connection between this element and the first layer is shorter (or more direct) than each mechanical connection that this element has with the substrate.

[0031] Symmetrically, unless otherwise stated, when referring to an element anchored, fixed, attached or attached to the substrate, this means that this element is mechanically coupled to the substrate, and that this element is mechanically coupled to the first layer via the substrate. For example, said another way, this means that the mechanical connection between this element and the substrate is shorter (or more direct) than each mechanical connection that this element has with the first layer.

[0032] Exemplary embodiments and alternative embodiments of such a device will now be described in relation to the figures 1 to 10 .

[0033] There figure 1 represents, by a schematic top view, an example of an embodiment of such a device 1. The figure 2 is a schematic sectional view of the device 1 taken in the plane AA of the figure 1 , there figure 3being a schematic sectional view of the device 1 taken in the plane BB of the figure 1 , there figure 4 being a schematic sectional view of the device 1 taken in the plane CC of the figure 1 and the Figure 5 being a schematic sectional view of the device 1 taken in the plane DD of the figure 1 .

[0034] The device 1 comprises a substrate 100, for example a semiconductor substrate. In other words, the circuit 1 is formed on the substrate 100. For example, the substrate 100 has a thickness of several hundred micrometers, for example a thickness of at least 200 µm. As an alternative example, the substrate 100 may have been thinned and have a thickness of less than 200 µm.

[0035] The device 1 further comprises a layer 102. For example, the thickness of the layer 102 is less than 100 µm, for example less than 10 µm, or even less than 1 µm.

[0036] The layer 102 comprises a portion 102A and a portion 102B. Preferably, each of the two portions 102A and 102B is suspended above the substrate 100, i.e., a free space is provided between the substrate 100 and each of these portions 102A and 102B. The portions 102A and 102B are movable relative to each other, preferably in a direction parallel to the substrate 100. In the example of figures 1 to 5 , the two parts 102A and 102B are movable relative to each other in a direction X, parallel to the substrate 100.

[0037] As an example, one of the portions 102A and 102B is fixed relative to the substrate and the other of the portions 102A and 102B is movable relative to the substrate 100, such that the portions 102A and 102B are movable relative to each other. As an alternative example, both portions 102A and 102B are movable relative to the substrate 100, such that both portions 102A and 102B are movable relative to each other.

[0038] For example, when a part 102A or 102B of the layer 102 is fixed relative to the substrate 100, this means that this part of the layer 102 is mechanically connected to another part of the layer 102 which is fixed to the substrate by a stack of layers in contact two by two, this stack being connected on the one hand to the substrate and on the other hand to this other part of the layer 102.

[0039] Furthermore, when a portion 102A or 102B is movable relative to the substrate 100, this means that this portion of the layer 102 is mechanically coupled to another portion of the layer 102 which is fixed to the substrate, for example by a stack of layers in contact two by two. This stack is connected on the one hand to the substrate and on the other hand to this other portion of the layer 102. Furthermore, the mechanical coupling of the movable portion 102A or 102B to this other portion of the layer 102 which is fixed to the substrate is implemented by deformable connections. Preferably, each deformable connection corresponds to, or comprises, a portion of layer 102. As an alternative example, each deformable connection corresponds to, or comprises, a portion of a layer other than the layer 102, the layer 102 resting on this other layer or this other layer resting on the layer 102.

[0040] In the particular example of figures 1 to 5, the part 102A is fixed relative to the substrate 100 and the part 102B is movable relative to the substrate 100, and therefore relative to the part 102A, for example in the X direction.

[0041] For example, portion 102A of layer 102 is mechanically connected to a portion 102C of layer 102, with portion 102C being attached to substrate 100 by a stack 104 of layers. Stack 104 is mechanically connected to substrate 100 and portion 102C of layer 102. figures 1, 2, 3 And 5 , the boundary between part 102A and part 102C of layer 102 is represented by a dotted line.

[0042] For example, portion 102B of layer 102 is coupled to portion 102D of layer 102, with portion 102D being attached to substrate 100 by a stack 106 of layers. The stack 106 is, for example, identical to the stack 104 except that the stack 106 is mechanically connected to the substrate 100 and to the portion 102D of the layer 102 instead of being mechanically connected to the substrate 100 and to the portion 102C of the layer 102. Furthermore, the portions 102B and 102D of the layer 102 are mechanically coupled to each other by deformable links 108, for example links 108 deformable in the X direction. The links 108 comprise, for example, each a portion of the layer 102. For example, each link 108 is a corresponding part of the layer 102. figure 4 , the boundaries between part 102B and links 108 on the one hand, and between links 108 and part 102D on the other hand are shown in dotted lines.

[0043] In the example of the figures 1 to 5 , each link 108 corresponds to a beam, for example defined in layer 102, each beam having one end connected to part 102D of layer 102 and another end connected to part 102B of layer 102. In other examples not illustrated, each link 108 corresponds to one or more meanders, for example defined in layer 102. The person skilled in the art will be able to provide other shapes for the links 108.

[0044] The device 1 further comprises an annular optical resonator 110. For example, the resonator has the shape of an athletics track ("racetrack" in English), that is to say a ring comprising two semi-circular parts connected to each other by two rectilinear parts.

[0045] The resonator 110 is formed in, or defined in, a layer 112. In other words, the resonator 110 is implemented by a portion of the layer 112. The layer 112 is made of a material suitable for guiding light at the operating wavelengths of the circuit 1. For example, the layer 112 is made of silicon, silicon nitride, arsenic gallium or germanium.

[0046] According to one embodiment, as illustrated by the figures 1 to 5 , the layer 112 is arranged between the substrate 100 and the layer 102. In this case, the stack 104 and / or the stack 106 may comprise a portion of the layer 112. In figure 1 , the elements, in particular the portions of layer 112, arranged under the layer 102 are delimited by dotted lines.

[0047] In a non-detailed and non-illustrated embodiment, the layer 112 is arranged above the layer 102, the layer 102 itself being arranged above the substrate 100.

[0048] Layer 112 is separated from layer 102 by a single layer 116.

[0049] The resonator 110 comprises a first portion 110A attached to the part 102A of the layer 102, and a second portion 110B attached to the part 102B of the layer 102. More precisely, the portion 110A of the resonator 110 is attached to an anchoring pad 114A which is mechanically connected to the part 102A of the layer 102, and the portion 110B of the resonator 110 is attached to an anchoring pad 114B which is mechanically connected to the part 102B of the layer 102. The portion 110A preferably corresponds to one of the two semicircular portions of the ring 110, the portion 110B preferably corresponding to the other of the two semicircular portions of the ring 110.

[0050] Preferably, the resonator 110 is not attached to the substrate 100, i.e., it is not attached to an anchor pad connected to the substrate 100.

[0051] Preferably, the device 1 comprises only two pads 114A and 114B making it possible to fix the resonator 110 to the layer 102.

[0052] Between the two portions 110A and 110B, the resonator comprises two portions 110C, for example rectilinear, each connecting the portion 110A to the portion 110B so that all of the portions 110A, 110B and 110C placed end to end form the ring of the resonator 110. Preferably, when the portions 110C are rectilinear, they are aligned with the direction X of movement of the parts 102A and 102B relative to each other. In other examples, these portions 110C may not be rectilinear, for example comprise one or more curves, although they are preferably each substantially aligned in the direction of their length with the direction X of movement.

[0053] When the two parts 102A and 102B of the layer 102 move relative to each other, this deforms, for example stretches or compresses, the portions 110C of the resonator 110, which causes a variation in its resonance wavelength. It is therefore the portions 110C of the resonator 110 which here act as an optomechanical deformation gauge.

[0054] The portion 110A, respectively 110B, of the resonator 110 is fixed to the pad 114A, respectively 114B, by one or more portions of the layer 112 each extending from the portion 110A, respectively 110B, to the pad 114A, respectively 114B.

[0055] Preferably, the anchoring pads 114A, 114B fixing the resonator 110 to the layer 102 are arranged inside the ring 110, that is to say that, in top view, the pads 114A, 114B are arranged in a region delimited laterally by the internal edge of the ring 114. Thus, each portion of the layer 112 which fixes the resonator 110 to a pad 114A or 114B is in contact with the internal edge of the resonator 110 rather than with the external edge of the resonator 110, which makes it possible to limit the optical losses in the resonator 110.

[0056] Each pad 114A, 114B comprises, for example, a portion of the layer 112 and a region 115 extending from this portion of the layer 112 to the layer 102. In other words, in each pad 114A, 114B, the region 115 is mechanically connected to the layer 102 and to the portion of the layer 112 forming part of the pad. For example, each region 115 corresponds to a portion of the layer 116. As an alternative example, each region 115 is made of a material different from that of the layer 116, so that the layer 116 can be selectively etched with respect to this material.

[0057] In an embodiment where the layer 112 is disposed between the substrate 100 and the layer 102, the layer 112 is separated from the substrate 100 by a single layer 117. In such an embodiment, each stack 104, 106 may then comprise a portion of the layer 116 and a portion of the layer 117 between which a portion of the layer 112 may be disposed. Furthermore, in such an embodiment, the resonator 110 is then suspended under a plane comprising the face of the layer 102 which is opposite the substrate 100, and above a plane comprising the face of the substrate 100 which is opposite the layer 102. More generally stated, the resonator 110 is then suspended from the layer 102, between the layer 102 and the substrate.

[0058] In an alternative embodiment (not shown) where layer 112 is disposed above layer 102, resonator 110 is suspended above layer 102. In such an alternative, when portion 102A or 102B is fixed relative to substrate 100, that portion of layer 102 may be attached to the substrate by a stack 104 of layers in pairwise contact rather than first being mechanically connected to another portion of layer 102 that is attached to substrate 100 by a stack 104 of layers. The portion 102A or 102B of layer 102 that is fixed relative to the substrate is then not suspended above substrate 100.

[0059] According to one embodiment, as illustrated by the figure 1 , in top view, the shape of each pad 114A, 114B is substantially that of a disc.

[0060] According to one embodiment, as illustrated by the figure 1, the portion 110A respectively 110B, of the resonator 110 is fixed to the pad 114A, respectively 114B, by beams 118A, respectively 118B, defined in the layer 112. In other words, the portion 110A respectively 110B, of the resonator 110 is fixed to the pad 114A, respectively 114B, by portions 118A, respectively 118B, of the layer 112, each portion 118A, 118B having the shape of a beam. Each beam 118A, respectively 118B, has one end connected to the portion 110A, respectively 110B, of the resonator 110, and another end connected to the pad 114A, respectively 114B.

[0061] According to one embodiment, each beam 118A, 118B has a substantially constant cross-section along its entire length. According to an alternative embodiment, each beam 118A, 118B has a smaller cross-section at its end connected to the resonator 110 than at its end connected to the pad.

[0062] According to one embodiment, the portions 110A, 110B and 110C of the resonator 110 each have a cross-section configured to allow single-mode guiding of the light in the resonator 110. Alternatively, the portions 110A and 110B may have a cross-section configured to allow multi-mode guiding of the light, and at least a central portion of each of the portions 110C has a cross-section configured to allow single-mode guiding of the light. In such an alternative, the person skilled in the art is able to ensure a gradual transition of the dimensions of the cross-section of the portions 110A and 110B towards the dimensions of the cross-section of the central parts of the portions 110C, so as to ensure a gradual variation of the effective optical index between these portions.

[0063] In order for light to propagate in the resonator 110, the device 1 further comprises a waveguide 120. The waveguide 120 is, like the resonator 110, defined in the layer 112, that is to say it corresponds to, or is constituted by, a portion of the layer 112. The waveguide 120 comprises a portion 122 which is optically coupled to the resonator 110.

[0064] For example, portion 122 of waveguide 120 is coupled to portion 110A of resonator 110 and is then attached to portion 102A of layer 102 as illustrated in the example of figures 1 to 5. As an alternative example, portion 122 of waveguide 120 is optically coupled to portion 110B of resonator 110 and is then attached to portion 102B of layer 102. Having portion 122 of waveguide 120 attached to the same portion 102A or 102B as portion 110A or 110B of the resonator with which portion 122 is optically coupled allows the optical coupling gap between waveguide 120 and resonator 110 to be kept constant.

[0065] Preferably, the portion 122 of the waveguide 120 extends longitudinally in a direction Y parallel to the substrate 100 and orthogonal to the direction X.

[0066] Preferably, when one of the parts 102A and 102B of the layer 102 is fixed relative to the substrate 100, the portion 122 of the waveguide 120 is fixed to this part fixed relative to the substrate, so as to avoid deformations of the waveguide 120 during a relative movement of the parts 102A and 102B relative to each other.

[0067] The portion 122 of the waveguide 120 is fixed to the layer 102 by holding arms 124 and anchoring pads 126.

[0068] The pads 126 are, for example, similar to the pads 114A, 114B, that is to say that they comprise stacks of similar layer portions and are each mechanically connected to the layer 102. For example, each pad 126 comprises a portion of the layer 112 and a region 115 corresponding to a portion of the layer 116 or to a material with respect to which the layer 116 can be selectively etched, the region 115 being connected to this portion of the layer 112 and to the layer 102.

[0069] Each holding arm 124 is, for example, a portion of the layer 112 extending from the portion 122 of the waveguide 120 to a corresponding pad 126, that is to say a portion of the layer 112 having one end connected to the portion 122 of the waveguide 120 and one end connected to this pad 126. In the example of figures 1 to 5, the arms 124 each have the shape of a beam although, in other examples not illustrated, each arm 124 may correspond to several beams placed end to end to form at least one meander or may have other shapes.

[0070] In Figure 5 , the boundary between the portion 122 of the waveguide 120 and each arm 124, and the boundary between each arm 124 and the portion of the layer 112 of the pad 126 to which this arm is connected are represented in dotted lines.

[0071] In an embodiment where layer 112 is disposed between layer 102 and substrate 100, portion 122 of waveguide 120 is, like resonator 110, suspended from layer 102, between layer 102 and substrate 100.

[0072] In an alternative embodiment (not shown) where layer 112 is disposed above layer 102, waveguide 120 is, like resonator 110, suspended above layer 102.

[0073] For example, during the manufacture of the circuit 1 in the case where the layer 112 is arranged between the layer 102 and the substrate 100, the layer 112 initially rests on the layer 117, itself resting on the substrate 100. Then different elements, including the resonator 110, are defined by etching in the layer 112. At this step of etching the layer 112, a portion of the layer 112 can be left in place at the location of each stack 104, 106, so that this stack comprises this portion of the layer 112. Then, the layer 116 is formed on the assembly and then the layer 102 is formed, by deposition or by transfer, on the layer 116. The region 115 of each anchor pad 114A, 114B, 126 can be made of the same material as the layer 102 in providing an opening in layer 116 up to layer 112, then filling the opening with material from layer 102 when depositing layer 102.Alternatively, the region 115 of each anchor pad 114A, 114B, 126 may be made of a material other than that of the layer 102 and that of the layer 116 by providing an opening in the layer 116 up to the layer 112, and by filling the opening with this material prior to the formation of the layer 102. Alternatively, the region 115 of each anchor pad 114A, 114B, 126 may correspond to a portion of the layer 116. Once the layer 102 is formed on the layer 116, portions of the layer 102 are removed during an etching step, then portions of the layers 116 and 117 are removed by selective sacrificial etching with respect to the layers 102 and 112 and to the substrate 100 to obtain the circuit 1. For example, when the regions 115 are made of a different material than that of layer 116, the etching(s) of layers 116 and 117 are also selective with respect to the material of regions 115.As an alternative example, when regions 115 are portions of layer 116, when etching layer 116, the person skilled in the art is able to provide openings in layer 102 and / or in layer 112 so that by controlling the etching time of layer 116 and / or layer 117, regions 115 are left in place at the end of etching. In the latter case, in each pad 114A, 114B and 126, region 115 may be slightly recessed relative to the outer edge of the pad.

[0074] In the example of the manufacturing method described above, when the layer 112 is a semiconductor layer, for example made of silicon, and the layer 117 is an insulating layer, for example made of silicon oxide, the layer 112 may correspond to the semiconductor layer of a semiconductor on insulator (SOI) type structure formed on the substrate 100.

[0075] In the example manufacturing method described above, in circuit 1, each stack 104, 106 comprises a portion of layer 117 left in place, and may or may not comprise a portion of layer 116 left in place. Indeed, it is possible to remove layer 116 from the stack by providing that layer 102 is formed by deposition, directly in contact with layer 112 at the location of the stack, layer 102 then being, for example, planarized.

[0076] As an alternative example, during the manufacture of the circuit 1 in the case where the layer 112 is arranged between the layer 102 and the substrate 100, the layer 102 corresponds to a portion of a first substrate, for example a semiconductor, for example made of silicon, the layer 116 then resting on this first substrate and the layer 112 then resting on the layer 116. In the same way as previously, elements, including the resonator 110, are formed in the layer 112. A filling material, for example identical to the material of the layer 116, is deposited and then planarized by stopping before or on the layer 112. The substrate 100 coated with the layer 117 is then transferred onto the structure before thinning the first substrate so as to leave only the layer 102. The following steps for obtaining the circuit 1 are then similar to what was described for the other example above.

[0077] In this other example of a manufacturing method, when layer 112 is a semiconductor layer, for example made of silicon, and layer 116 is an insulating layer, for example made of silicon oxide, layer 112 may correspond to the semiconductor layer of a semiconductor on insulator (SOI) type structure formed on the first substrate.

[0078] Of course, the two ways of manufacturing the circuit 1 which are described above are only examples, and the person skilled in the art is able, from the present description, to provide other methods of manufacturing the circuit 1 using steps which are each usual in the manufacturing of photonic circuits. In particular, the person skilled in the art is able to provide the manufacturing methods for manufacturing the circuit 1 in the case where the layer 112 is arranged above the layer 102.

[0079] Preferably, the circuit 1 comprises only one layer 116 and one layer 117. However, the layer 116 may correspond to a plurality of layers stacked on top of each other and / or the layer 117 may correspond to a plurality of layers stacked on top of each other.

[0080] For example, the two sacrificial layers 116 and 117 are made of the same material, selectively etchable relative to the material(s) of the layers 102 and 112, of the substrate 100, and, for example, of each region 115. However, in other examples, the layers 116 and 117 may be made of different materials, each selectively etchable relative to the material(s) of the layers 102 and 112, of the substrate 100, and, for example, of each region 115.

[0081] For example, the substrate 100 is made of silicon or arsenic-gallium.

[0082] For example, layer 117 is a layer of silicon oxide or a photonic polymer such as, for example, BCB (benzocyclobutene).

[0083] For example, layer 116 is a silicon oxide layer.

[0084] For example, each region 115 is made of silicon, silicon nitride, or silicon oxide.

[0085] Of course, the person skilled in the art is able to adapt the materials of the layers 116, 112, 117 and 102, of the substrate 100 and, for example, of the regions 115 while retaining the etching selectivities indicated previously.

[0086] For example, the thickness of the layer 112 is between 40 and 1000 nm, for example between 50 and 500 nm.

[0087] For example, the thickness of layer 116 is greater than 500 nm, so that layer 102 does not modify the optical properties of resonator 110.

[0088] For example, the thickness of the layer 117 is greater than 500 nm so that the substrate 100 is sufficiently far from the resonator 110 so as not to modify its optical properties.

[0089] Of course, the person skilled in the art is able to adapt the thicknesses of the layers 116, 112, 117 and 102 of the substrate 100.

[0090] For example, when the device 1 is at rest (no relative movement between the parts 102A and 102B of the layer 102), Lg is the length of each of the portions 110C, Ltot is the total length of the resonator 110, n is the effective optical index in the portions 110C and λ is the resonance wavelength of the resonator 110. During a relative movement of the parts 102A and 102B relative to each other, the portions 110C deform accordingly, resulting in a variation DLg of the length of each of the portions 110C and a variation Dn of the effective optical index in these portions 110C. This results in a modification Dλ of the resonance wavelength of the resonator 110. Considering that the portions 110A and 110B are not deformed, the above parameters are linked together by the following equation: Dλ / λ = A*((DLg / Lg) + (Dn / n)), with A a form factor equal to 2*Lg / Ltot.

[0091] The device 1 described here makes it possible to obtain dynamic measurement ranges having extents, or widths or amplitudes, greater than those of known strain gauges. For example, for a device 1 operating in open loop, that is to say without control of the wavelength of the light supplied to the waveguide 120 on the resonance wavelength of the resonator 110, for a measurement bandwidth equal to 10 KHz and fixed by the reading electronics, and a laser having a relative intensity noise of the order of 10 -8< , the dynamic measurement range can be greater than 10 6< , although the bandwidth offered by the optical cavity of the device 1, equal to λ / Q with Q the quality factor of the resonator 110, is higher.Although it has been indicated above that the device 1 operates in an open loop, the person skilled in the art is able to provide for a control of the wavelength of the light circulating in the waveguide 120 on the wavelength of the resonator 110 when this resonance wavelength varies following a displacement of the two parts 102A and 102B of the layer 102 relative to each other.

[0092] Furthermore, the optical measurement bandwidth is large, e.g., from a few GHz to 100 GHz, although in practice it is limited by the mechanical response of the system. For comparison, a piezoresistive gauge has a much smaller measurement bandwidth and is limited by the product of the gauge resistance and the gauge capacitance (RC product).

[0093] Furthermore, device 1 has a noise threshold for reading the deformation of the resonator which is very low compared to the noise threshold for reading conventional deformation gauges.

[0094] In device 1, portion 122 of waveguide 120 is attached to layer 102. The fact that this portion 122 of waveguide 120 is attached to part 102A of layer 102 when portion 122 is optically coupled to part 110A of the resonator, or to part 102B of layer 102 when portion 122 is optically coupled to part 110B of resonator 110, makes it possible to keep constant the optical gap between waveguide 120 and resonator 110 where optical coupling of waveguide 120 with resonator 110 takes place. Although not claimed here, portion 122 of the waveguide could be attached to substrate 100 rather than layer 102, but in this case the aforementioned advantage of keep the optical coupling gap between the waveguide 120 and the resonator 110 constant, which could distort the measurement.

[0095] There figure 6represents, by a partial and schematic top view, an alternative embodiment of a part of the device 1 of the figures 1 to 5 , and, more particularly, plots 114A, 114B of the device 1. In figure 6 , only the portion 110B of the resonator 110, the pad 114B and the arms 118B have been shown, the description of these elements being directly transposable to the portion 110A of the resonator 110, to the pad 114A and to the arms 118A. Only the differences between the embodiment described in relation to the figures 1 to 5 and the variant embodiment of the figure 6 are described here.

[0096] In this variant, the stud 114B has, in top view, the shape of a half-disc rather than that of a disc as has been described in relation to the figures 1 to 5The center of the half-disc 114B, that is to say of a disc which would be formed by the half-disc 114B and another half-disc, is coincident with the center of the portion 110B in an arc of a circle, that is to say the center of a circle which would be formed by the portion 110B in a semicircle and another portion in a semicircle. Furthermore, the curved part of the half-disc 114B is turned towards the portion 110B of the resonator, or, more precisely, the entire curved edge of the pad 114B is, in a plane parallel to the substrate 100, opposite the portion 110B of the resonator 110.

[0097] There figure 7 represents, by a partial and schematic top view, another variant embodiment of a part of the device 1 of the figures 1 to 5 , and, more particularly arms 118A, 118B of device 1. In figure 7, only the portion 110B of the resonator 110, the pad 114B and the arms 118B have been shown, the description of these elements being directly transposable to the portion 110A of the resonator 110, to the pad 114A and to the arms 118A. Only the differences between the embodiment variant described in relation to the figure 6 and the variant embodiment of the figure 7 are described here.

[0098] In this variant, the arms 118B are beams defined in the layer 112. However, instead of having a constant cross-section along its entire length, each beam 118B has a larger cross-section on the side of the pad 114B than on the side of the portion 110B of the resonator 110. For example, each beam 118B has, on the side of its end connected to the pad 114B, a cross-section which increases as it approaches the pad 114B.

[0099] This embodiment variant applies to cases where the pad 114B has a shape other than that of a half-disc, for example the shape of a disc.

[0100] The provision of beams 118B having larger cross-sections on the side of the pad 114B than on the portion 110B of the resonator 110 makes it possible to increase the rigidity of the beams 118B without increasing the optical losses in the resonator 110 compared to the case of beams 118B which would have constant cross-sections over all their lengths.

[0101] There figure 8 represents, by a partial and schematic top view, yet another variant embodiment of a part of the device 1 of the figures 1 to 5 , and, more particularly of the way in which the portions 110A and 110B are fixed to the respective pads 114A and 114B by portions of the layer 112. In figure 8, only the portion 110B of the resonator 110, the pad 114B and a portion 800 of the layer 112 fixing the portion 110B to the pad 114B have been represented, the description of these elements being directly transposable to the portion 110A of the resonator 110, to the pad 114A and to a portion of the layer 112 fixing the portion 110A to the pad 114A.

[0102] Only the differences between the embodiment variant described in relation to the figure 6 and the variant embodiment of the figure 8 are described here.

[0103] More particularly, in this variant, instead of the portion 110B of the resonator 110 being fixed to the pad 114B by arms 118B defined in the layer 112, the portion 110B of the resonator 110 is fixed to the pad 114B by a portion 800 of the layer 112.

[0104] The portion 800 of the layer 112 fills the space between the pad 114B and the semicircular portion 110B of the resonator 110. In this example where the pad 114 has the shape of a half-disc, the assembly of the portion 110B of the resonator 110, of the portion 800 of the layer 112 and of the pad 114B, and, more particularly, of the portion of layer 112 forming part of the pad 114B, forms a half-disc.

[0105] The portion 800 of the layer 112 is provided with several through openings 802, that is to say openings 802 passing through the layer 112 over its entire thickness. figure 8, only one opening 802 is referenced so as not to overload the figure. The openings 802 are for example configured to implement a photonic crystal structure in the portion 800. As an alternative example, a portion of the openings 802 implements a photonic crystal structure and another portion of the openings 802 makes it possible to generate high propagation losses on optical modes propagated in the portion 800 and which it is desired to eliminate, i.e. to filter. The photonic crystal structure is configured so that the light guided in the resonator 110 remains confined in the resonator 110, and, more particularly, in the portion 110B of the resonator 110 when it propagates in this portion 110B. In other words, the portion 800 and the openings 802 are configured to favor a single optical propagation mode in the portion 110B.

[0106] This embodiment variant applies to cases where the pad 114B has a shape other than that of a half-disc, for example the shape of a disc.

[0107] There figure 9 represents, by a partial and schematic top view, yet another variant embodiment of a part of the device 1 of the figures 1 to 5 , and, more particularly of the way in which the portions 110A and 110B are fixed to the respective pads 114A and 114B by portions of the layer 112. In figure 9 , only the portion 110B of the resonator 110, the pad 114B and a portion 900 of the layer 112 fixing the portion 110B to the pad 114B have been represented, the description of these elements being directly transposable to the portion 110A of the resonator 110, to the pad 114A and to a portion of the layer 112 fixing the portion 110A to the pad 114A.

[0108] Only the differences between the embodiment variant described in relation to the figure 8 and the variant embodiment of the figure 9 are described here.

[0109] More particularly, in this variant, the portion 800 of layer 112 is replaced by a portion 900 of layer 112 identical to the portion 800 except that it does not include the openings 802.

[0110] In this variant, the propagation of light in the portion 110B is multimode, the portion 110B then having a larger cross-section than that of the central portions 110C of the resonator which is adapted to single-mode propagation. Preferably, as illustrated in figure 9 , a gradual transition from the cross-sectional dimensions of portion 110B to the cross-sectional dimensions of the central portions of portions 110C may be provided, so as to ensure a gradual variation in the effective optical index between these portions.

[0111] In the various embodiments and alternative embodiments described above, preferably, the manner in which the portion 110A, respectively 110B, of the resonator is fixed to the part 102A, respectively 102B, is preferably configured so that the portions 110A and 110B of the resonator do not deform during a relative movement of the parts 102A and 102B relative to each other.

[0112] There figure 10 represents, by a schematic top view, another example of an embodiment of the device 1.

[0113] In this embodiment, preferably the portion 102A of the layer 102 is fixed relative to the substrate 100.

[0114] In this embodiment, the layer 102 of the device 1 comprises a portion 102E suspended above the substrate 100. Preferably, the portion 102E has, in a plane parallel to the substrate 100, dimensions greater than those of the portion 102B. This portion 102E is movable relative to the substrate 100 in a plane parallel to the substrate 100, for example in a direction identical to the direction X of movement of the portions 102A and 102B relative to each other.

[0115] In this embodiment, the layer 102 further comprises a lever arm 102F, 102G. The lever arm 102F, 102G is configured such that a displacement of the portion 102E in the X direction results in a corresponding, but smaller, displacement of the portion 102B in the X direction. The lever arm 102F, 102G is also suspended above the substrate 100.

[0116] According to one embodiment, the arm 102F, 102G is defined in the layer 102. Alternatively, all or part of the lever arm 102F, 102G may be defined in another of the layers of the device 1.

[0117] The lever arm 102F, 102G here comprises a beam 102F. In this example, the beam 102F is defined in the layer 102. The beam 102F extends lengthwise in the Y direction. The beam 102F has one end mechanically connected to the portion 102E, and another end fixed relative to the substrate 100. The lever arm 102F, 102G further comprises an element 102G. The element 102G is, in this example, defined in the layer 102. The layer portion 102G has, for example, a beam shape aligned along the X direction. The beam 102G is suspended above the substrate 100. The beam 102G is mechanically connected to the portion 102B and to the arm 102F on the side of the fixed end of the arm 102F. The portion 102G of the layer 102 is configured to transmit the movements of the arm 102F in the X direction to the portion 102B of the layer 102.For example, the stiffness of portion 102G in the X direction is at least five times greater than the stiffness of portions 110C of resonator 110 in the X direction.

[0118] More specifically, in the example of the figure 10 , the beam 102F constitutes an axis whose end which is fixed to the part 102 can move in rotation, in a plane parallel to the substrate 100, around the end of the axis which is fixed relative to the substrate. This rotation of the end of the axis 102F which is fixed to the part 102E, that is to say the rotation of the part 102E relative to the fixed end of the axis 102F, is considered locally as a translation of the part 102E in the direction X relative to the substrate 100. This rotational movement is transmitted in the form of a translational movement in the direction X to that of the parts 102A and 102B which is movable relative to the substrate 100, by means of the element 102G.

[0119] In other words, in the example of the figure 10 , the lever arm is configured to transform a rotational movement, in a plane parallel to the substrate, of the part 102E around the fixed end of the axis 102F into a translational movement, still in a plane parallel to the substrate, of the part 102B.

[0120] By means of the lever arm 102F, 102G there is a linear relationship connecting a displacement of the portion 102E in the X direction and a correspondingly smaller displacement of the portion 102B in the X direction. Thus, the lever arm 102F, 102G allows the displacements of the portion 102B in the X direction to remain in a range where the material of the portions 110C of the resonator 110 is in an elastic deformation regime, while allowing the measurement of displacements of the portion 102E in the X direction and relative to the substrate 100 which are much larger than those of the portion 102B in the X direction and relative to the substrate 100.For example, calling Lb the distance between the fixed end of arm 102F and the center of part 102E, and Lp the distance between the fixed end of arm 102F and the mechanical connection between arm 102F and part 102G, a displacement of part 102E in the X direction causes a displacement of part 102B in the direction which is Lb / Lp times smaller.

[0121] For example, the fixed end of the axis or beam 102F is connected to the ends of two beams 102H1 and 102H2, for example defined in the layer 102, and forming, in a plane parallel to the substrate 100, a right angle between them at the fixed end of the arm 102F. The other ends of the beams 102H1 and 102H2 are mechanically connected to a portion 102J of the layer 102 which is fixed relative to the substrate. Thus, the two beams 102H1 and 102H2 implement a pivot connection on the fixed end of the arm 102F. In the case where such a pivot connection is implemented, the torsional stiffness of the portion 102G of the layer 102 is preferably less than that of the pivot connection.

[0122] Although described herein is the case where the lever arm 102F allows movement of the portion 102E in the X direction to cause a correspondingly smaller movement of the portion 102B in the X direction, one skilled in the art would be able to foresee that the lever arm 102F allows movement of the portion 102E in the X direction to cause a correspondingly larger movement of the portion 102B in the X direction.

[0123] Furthermore, the person skilled in the art is able to provide other lever arm configurations allowing that a movement, in a plane parallel to the substrate 100, of the portion 102E relative to the substrate 100 causes, by means of the lever arm, a corresponding movement in this plane of the portions 102A and 102B relative to each other.

[0124] More generally, a lever arm designates, in the present description, a system making it possible to convert a rotational movement of the part 102E into a translational movement, preferably in the X direction, of that of the parts 102A and 102B which is movable relative to the substrate 100. An example has been described above in the case where a movement of the part 102E in a plane parallel to the substrate 100 is transmitted by the lever arm 102F to one of the parts 102A and 102B (the part 102B in figure 10) so as to result in a corresponding movement of the parts 102A and 102B relative to each other in the plane. The person skilled in the art will also be able to provide a device 1 comprising a lever arm configured so that a rotational movement of a part 102E of the layer 102 about an axis parallel to the substrate 100 is transmitted in the form of a translational movement corresponding to that of the parts 102A and 102B which is movable relative to the substrate 100. In this case, the movement of the part 102E is not in a plane parallel to the substrate 100 as is the case in figure 10 , but at least partly in a direction orthogonal to the substrate 100.

[0125] For example, taking the figure 10, by mechanically connecting or mechanically fixing an edge of the part 102E along the beam 102F, and no longer at one end thereof as previously described, and by making fixed the end of the axis 102F which was previously movable relative to the substrate 100, the part 102E can then move relative to the substrate 100 according to a rotational movement around the axis 102F which is fixed and parallel to the substrate 100. This rotational movement around an axis parallel to the substrate 100, and, more particularly parallel to the Y axis in this example, is then transmitted by the element 102G in the form of a corresponding translational movement, in a plane parallel to the substrate, of the part 102A or 102B which is movable relative to the substrate 100, for example a translational movement in the X direction.In this case, the element 102G corresponds for example to a portion of the layer 112, for example in the form of a beam aligned in the X direction, having one end fixed to the part 102A or 102B which is movable relative to the substrate 100, and another end fixed to the part 102E.

[0126] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. In particular, although it has been described in connection with the figures 1 , 6 , 7, 8 and 9that the shape of the pads 114A, 114B and their attachments to the respective portions 110A, 110B of the resonator 110 by respective beams 1181, 118B or portions 800 of layer 110 provided with openings are identical for each pad, in alternative embodiments not illustrated the two pads 110A and 110B may be different from each other and / or the way in which the pad 114A is attached to the portion 110A may be different from that in which the pad 114B is attached to the portion 110B. For example, the pads and resonator may be as illustrated in figure 8 with respect to pad 114B and portion 110B of resonator 110, and as illustrated in figure 1 with respect to pad 114A and portion 110A of resonator 110.

Claims

1. Device (1) comprising: a substrate (100); a first layer (102) resting on the substrate, the first layer comprising a first part (102A) and a second part (102B) mobile with respect to each other; an annular optical resonator (110) defined in a second layer (112), the device being characterized in that the resonator (110) comprises a first portion (110A) fixed to a first anchor pad (114A) connected to the first part (102A) of the first layer (102) and a second portion (110B) fixed to a second anchor pad (114B) connected to the second part (102B) of the first layer (102).

2. Device according to claim 1, wherein the first and second anchor pads (114A, 114B) are arranged inside of the resonator (110).

3. Device according to claim 1 or 2, wherein the first and second portions (110A, 110B) of the resonator (110) each have a semi-circle shape.

4. Device according to claim 3 as dependent on claim 2, wherein: the first pad (114A) has a shape of a half-disk having its center forming one with the center of the first portion (110A) of the resonator (110) and its curved portion facing the first portion (110A) of the resonator (110); and / or the second pad (114B) has a shape of a half-disk having its center forming one with the center of the second portion (110B) of the resonator (110) and its curved portion facing the second portion (110B) of the resonator (110).

5. Device according to any of claims 1 to 4, wherein: the first portion (110A) of the resonator is fixed to the first pad (114A) by first beams (118A) defined in the second layer (112), each of the first beams (118A) having a first end connected to the resonator (110) and a second end connected to the first pad (114A); and / or the second portion (110B) of the resonator is fixed to the second pad (114B) by second beams (118B) defined in the second layer (112), each of the second beams (118B) having a first end connected to the resonator (110) and a second end connected to the second pad (114B).

6. Device according to claim 5, wherein each of the first and second beams (118A, 118B) has a larger cross-section area on the side of its second end than on the side of its first end.

7. Device according to any of claims 1 to 4, wherein: the first portion (110A) of the resonator is fixed to the first pad (114A) by a first continuous portion (900) of the second layer (112), the assembly of the first portion (110A) of the resonator, of the first portion (900) of the second layer (112), and of the first pad (114A) having a shape of a half-disk; and / or the second portion (110B) of the resonator is fixed to the second pad (114B) by a second continuous portion (900) of the second layer (112), the assembly of the second portion (110B) of the resonator (110), of the second portion (900) of the second layer (112), and of the second pad (114B) having a shape of a half-disk.

8. Device according to any of claims 1 to 4, wherein: the first portion (110A) of the resonator is fixed to the first pad (114A) by a first portion (800) of the second layer (112), the assembly of the first portion (110A) of the resonator, of the first portion (800) of the second layer (112), and of the first pad (114A) having a shape of a half-disk, and the first portion (800) of the second layer (112) comprises through openings (802) configured to favor a single optical propagation mode in the first portion (110B) of the resonator (110); and / or the second portion (110B) of the resonator is fixed to the second pad (114B) by a second portion (800) of the second layer (112), the assembly of the second portion (110B) of the resonator (110), of the second portion (800) of the second layer (112), and of the second pad (114B) having a shape of a half-disk, and the second portion (800) of the second layer (112) comprises through openings (802) configured to favor a single optical propagation mode in the second portion (110B) of the resonator (110).

9. Device according to any of claims 1 to 8, wherein the resonator (110) comprises a third portion (110C) coupling the first portion (110A) of the resonator to the second portion (110B) of the resonator, and another third portion (110C) coupling the second portion (110B) of the resonator to the first portion (110A) of the resonator, the assembly of the first, second, and third portions (110A, 110B, 110C) forming the ring of the resonator (110).

10. Device according to claim 9, wherein each of the first and second portions (110A, 110B) of the resonator has a cross-section configured to allow a multimode guiding of light, and each of the third portions (110C) has a central portion having a cross-section configured to allow a monomode guiding of light.

11. Device according to any of claims 1 to 10, wherein the first and second parts (102A, 102B) of the first layer (102) are mobile with respect to each other in a first direction (X) parallel to the substrate (100).

12. Device according to any of claims 1 to 11, wherein the second layer (112) is arranged between the substrate (100) and the first layer (102), the first and second parts (102A, 102B) of the first layer (102) being suspended above the substrate (100).

13. Device according to any of claims 1 to 12, wherein the device (1) further comprises a waveguide (120) defined in the second layer (112) and having a portion (122) optically coupled to the resonator (110), said portion (122) of the waveguide (120) being either optically coupled to the first portion (110A) of the resonator (110) and fixed to the first part (102A) of the first layer (102), or optically coupled to the second portion (110B) of the resonator (110) and fixed to the second part (102B) of the first layer (102) .

14. Device according to any of claims 1 to 13, wherein: the first part (102A) of the first layer (102) is fixed with respect to the substrate (100); the first layer (102) further comprises a third part (102E) suspended above the substrate (100) and mobile with respect to the substrate (100) in a plane parallel to the substrate; and the device comprises a lever arm (102F, 102G), for example at least partly defined in the first layer (102), configured so that a displacement of the third portion (102E) with respect to the substrate (100) in said plane parallel to the substrate (100) causes a corresponding displacement of the second part (102B) of the first layer (102) with respect to the first part (102A) of the first layer (102) in said plane parallel to the substrate (100).

15. Device according to any of claims 1 to 13, wherein: the first part (102A) of the first layer (102) is fixed with respect to the substrate (100); the first layer (102) further comprises a third part (102E) suspended above the substrate (100) and rotatably mobile around an axis (Y) parallel to the substrate (100); and the device comprises a lever arm (102F, 102G), for example partly defined in the first layer (102), configured so that a rotation of the third part (102E) around said axis (Y) causes a corresponding displacement of the second part (102B) of the first layer (102) with respect to the first part (102A) of the first layer (102) in a plane parallel to the substrate (100).