OPTOELECTRONIC PRESSURE SENSOR

Abstract

Optoelectronic pressure sensor (100) comprising: an optical resonator (110), the optical resonator (110) comprising: a first mirror layer structure (111), a second mirror layer structure (114), a third mirror layer structure (116) and a first spacer layer (112) arranged between the first mirror layer structure (111) and the second mirror layer structure (114), and a second spacer layer (115) arranged between the second mirror layer structure (114) and the third mirror layer structure (116), wherein at least the first spacer layer (112) or the second spacer layer (115) comprises an elastic material and is configured such that at least one property of the optical resonator (110) is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator (110); at least one radiation source (120) for generating electromagnetic radiation (120e), wherein the optical resonator (110) and the radiation source (120) are configured such that the generated electromagnetic radiation (120e) is coupled into the optical resonator (110); and at least one optical sensor (140) for detecting electromagnetic radiation coupled into the optical resonator (110); wherein the first spacer layer (112) comprises a first elastic material and wherein the second spacer layer (115) comprises a second elastic material different from the first elastic material.

Description

[0001] In general, optoelectronic pressure sensors can be used in a wide variety of applications. Numerous different pressure sensors with different principles are already known. These include piezo sensors, which are currently among the smallest and most energy-efficient sensors. However, the accuracy of piezo sensors, which is typically up to 5%, is not sufficiently high for some applications. Other pressure sensors, which may provide more precise measurement results, are often heavy and bulky, and such pressure sensors are generally not easily adaptable for a wide variety of applications.

[0002] US 2015 / 0 268 117 A1 describes a pressure sensor cable with a polarization-maintaining optical fiber. A fiber Bragg grating (FBG) pair is formed in the optical fiber. The FBG pair includes a first FBG defining a first wavelength range in which the first FBG is reflective. The FBG pair further includes a second FBG spaced apart from the first FBG to define a cavity between the first FBG and the second FBG. The second FBG defines a second wavelength range in which the second FBG is reflective. The first wavelength range and the second wavelength range at least partially overlap.

[0003] DE 10 2020 104 154 A1 describes an ultrasonic sensor with an optical resonator formed from two dielectric mirror layers arranged at a distance from each other. A compressible layer is arranged between the two mirror layers, so that a property of the resonator, namely the wavelength of the electromagnetic radiation generated in the optical resonator, is varied when the compressible layer is compressed or expanded.

[0004] Various embodiments relate to an optoelectronic pressure sensor that can be cost-effective and energy-efficient, wherein the optoelectronic pressure sensor can clearly have improved measurement accuracy and an improved service life. According to various embodiments, the optoelectronic pressure sensor can further detect both static pressures and dynamic pressures within a wide and easily adjustable pressure range.

[0005] In various aspects, an optoelectronic pressure sensor is provided. The optoelectronic pressure sensor may comprise an optical resonator. The optical resonator may comprise one or more optical resonant structures, wherein each one may form n mirror layers and n-1 spacer layers located therebetween, corresponding to n-1 resonant structures. The optical resonator may, for example, comprise a first mirror layer structure, a second mirror layer structure, a third mirror layer structure, a first spacer layer, and a second spacer layer. The first spacer layer may be arranged between the first mirror layer structure and the second mirror layer structure. Furthermore, the second spacer layer may be arranged between the second mirror layer structure and the third mirror layer structure.The first spacer layer and the second spacer layer comprise an elastic material, which are configured such that at least one property of the optical resonator can be varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator. The first spacer layer comprises a first elastic material, and the second spacer layer comprises a second elastic material that is different from the first elastic material.

[0006] The optoelectronic pressure sensor may further comprise a radiation source for generating electromagnetic radiation, and an optical sensor arranged outside the optical resonator for detecting electromagnetic radiation emerging from the optical resonator. The optical resonator and the radiation source may be configured such that the generated electromagnetic radiation can be coupled into the optical resonator.

[0007] Thus, various embodiments clearly provide a compact, reliable, cost-effective, and energy-efficient optoelectronic pressure sensor, which can clearly have better measurement accuracy, for example, due to the two resonant structures (a resonant structure can be formed from two mirror layers and a spacer layer, corresponding to an optical resonator) and the resulting numerous resonant modes, and which can have a simple structural design. This can have the advantage of keeping manufacturing costs low. Furthermore, such an optoelectronic pressure sensor can detect external pressure over a wide and easily adaptable pressure range.

[0008] According to various embodiments, the optoelectronic pressure sensor can be configured such that the optical modes are coupled (leading, for example, to different periodicities). For example, a crossing of a static mode (avoided crossing due to the coupling of both modes) with variable modes can be avoided by varying the thickness of a spacer layer. This can lead to two different characteristic signals, whose relative amplitude and periodicity can be evaluated. This allows the thickness of the spacer layer, and thus the compression state, to be precisely determined across multiple mode orders (number of avoided "crossings").

[0009] In a non-claimed example, an optoelectronic pressure sensor is provided, comprising: an optical resonator with one or more (coupled) resonance structures, wherein each of the one or more resonance structures is formed by a respective pair of mirror layer structures and a spacer layer arranged within the pair of mirror layer structures (e.g. a compressible spacer layer), wherein at least one spacer layer of the one or more resonance structures comprises an elastic material and is configured such that at least one property of the optical resonator is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator;at least one radiation source for generating electromagnetic radiation in a first wavelength range and in a second wavelength range, wherein the optical resonator and the radiation source are configured such that the generated electromagnetic radiation is coupled into the optical resonator;and a sensor arrangement configured to detect electromagnetic radiation emerging from the optical resonator in the first wavelength range and in the second wavelength range and to output a first measurement signal representing an intensity of the detected electromagnetic radiation in the first wavelength range and a second measurement signal representing an intensity of the detected electromagnetic radiation in the second wavelength range, for determining an external pressure acting on the optical resonator based on the first measurement signal and the second measurement signal.

[0010] According to various embodiments, one or more elastic layers can also be integrated into the mirror layer structure, so that no separate compressible spacer layer is necessary to enable the corresponding functionality of the optoelectronic pressure sensor.

[0011] By using at least two wavelength ranges for measuring the pressure, it is possible to achieve, in addition to an improved measurement accuracy of the external pressure exerted on the pressure sensor, for example, to determine the absolute pressure value and / or the fatigue of the optoelectronic pressure sensor.

[0012] Embodiments are shown in the figures and are explained in more detail below.

[0013] They show: Fig. 1 a schematic cross-sectional view of an optoelectronic pressure sensor, according to various embodiments; Fig. 2 a schematic cross-sectional view of an optoelectronic pressure sensor, according to various embodiments; Fig. 3A and Fig. 3B each shows a graphic of an exemplary characteristic field of an optoelectronic pressure sensor, according to various embodiments; Fig. 4 shows an exemplary measurement of a transmission spectrum of an optoelectronic pressure sensor, according to various embodiments; Fig. 5 different calibration curves of an optoelectronic pressure sensor, according to different embodiments; and Fig. 6 is a graph showing an example of a periodic sensor signal with a continuous change of the mirror layer spacing of an optoelectronic pressure sensor, according to various embodiments.

[0014] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology such as "top," "bottom," "front," "back," "fore," "rear," etc., will be used with reference to the orientation of the described figure(s). Since components of embodiments can be positioned in a number of different orientations, the directional terminology is for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention.It is understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following description is therefore not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0015] Fig. 1 illustrates a schematic cross-sectional view of an optoelectronic pressure sensor, according to various embodiments.

[0016] According to various embodiments, the optoelectronic pressure sensor 100 can comprise an optical resonator 110. The optical resonator 110 can comprise a first mirror layer structure 111, a second mirror layer structure 114, a third mirror layer structure 116, as well as a first spacer layer 112, which can be arranged between the first mirror layer structure 111 and the second mirror layer structure 114, and a second spacer layer 115, which can be arranged between the second mirror layer structure 114 and the third mirror layer structure 116. At least the first spacer layer 112 and the second spacer layer 115 each comprise an elastic material and are configured such that at least one property of the optical resonator 110 can be varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator 110.The optoelectronic pressure sensor 100 may further comprise at least one radiation source 120 (see, for example, . Fig. 2) for generating electromagnetic radiation 120e. The optical resonator 110 and the radiation source 120 can be configured such that the generated electromagnetic radiation 120e can be coupled into the optical resonator 110. The optoelectronic pressure sensor 100 can further comprise at least one optical sensor 140 arranged outside the optical resonator 110 (see, for example, Fig. 2) for detecting electromagnetic radiation emerging from the optical resonator 110.

[0017] According to various embodiments, a mirror layer structure may comprise or consist of a mirror layer sequence.

[0018] The three mirror layer structures, each with a spacer layer (also called separation layer) between the respective mirror layer structures, can thus form two resonance structures (also called resonance cavities).

[0019] According to various embodiments, an optoelectronic pressure sensor 100 can thus be provided, which can be configured to measure an external mechanical pressure by means of light absorption based on two optical (micro)cavities, wherein at least one of the two optical (micro)cavities can be compressible and / or expandable. The light (or generally the electromagnetic radiation) can be captured (and, for example, reflected by at least 99% in each case) between the first and second mirror layer structures 111, 114 and between the second and third mirror layer structures 114, 116.

[0020] Thus, for example, at least one standing wave can be established depending on the distance between the first mirror layer structure and the second mirror layer structure, and depending on the distance between the second mirror layer structure and the third mirror layer structure. Thus, for example, at least one corresponding cavity mode (or interface state) can arise. Because the optoelectronic pressure sensor can have one or more resonance structures, multiple resonant modes can be supported. For example, multiple resonant modes can arise due to the distance of the mirror layer structure and / or a coupling of multiple resonant modes can occur that arise at two different interfaces or in gaps (with at least three mirror layer structures).The resonance wavelengths of the different resonant modes can be in such a relationship that they can completely or partially overlap.

[0021] The at least one standing wave can react very sensitively with a change in wavelength to a change in the layer thickness of the first spacer layer 112, which defines the distance between the first and second mirror layer structures 111, 114 and can change accordingly to the change in the layer thickness.

[0022] In various embodiments, the transmission signal that can emerge from the optical resonator 110 can change depending on the at least one cavity mode. The transmission signal can then be detected by the optical sensor 140 and converted into an electrical measurement signal and evaluated. Since the absorption of light is wavelength-dependent, a change in the layer thickness of the first spacer layer (and / or the second spacer layer), which can change the wavelength, can thus also change the measurement signal.

[0023] Illustratively, the optoelectronic pressure sensor 100 can be pressure-sensitive due to a change in the thickness of the spacer layer, and an electrical signal can be output by the optical sensor 140, representing the pressure or the pressure change. The mode reacts very sensitively to changes in the overall layer thickness, for example, the distance between the first mirror layer structure 111 and the second mirror layer structure 115, so that, for example, changes in the mechanical pressure exerted on the optoelectronic pressure sensor can be analyzed and / or pressure changes can be analyzed very quickly and / or accurately. This functional principle can enable a measurement accuracy of up to approximately 1% of the applied total pressure.

[0024] Because the optoelectronic pressure sensor can be based on at least one cavity mode whose wavelength can react sensitively to pressure, the optoelectronic pressure sensor can have a simple structure, which, for example, allows manufacturing costs to be kept low and the optoelectronic pressure sensor can be energy-efficient.

[0025] A further advantage of the optoelectronic pressure sensor according to the invention may be, for example, that the dimensions of the optoelectronic pressure sensor can be easily adapted to specific areas of application. For example, due to its compactness, the optoelectronic pressure sensor can be easily integrated into microelectronic systems, whereby the optoelectronic pressure sensor, for example for industrial robots, can measure or detect pressure changes in a range of 0.1 kPa to 100 kPa. Alternatively, the optoelectronic pressure sensor can be designed for applications with pressure changes in a range of 1 MPa to 100 MPa (which can be achieved, for example, by using different compressible layers), for example as a pressure sensor for bridges.

[0026] Thus, various embodiments clearly provide a compact, reliable, cost-effective, and energy-efficient optoelectronic pressure sensor, which can clearly achieve better measurement accuracy, for example, due to the two resonant structures and the resulting numerous resonant modes, and which can have a simple structural design. This can have the advantage of keeping manufacturing costs low. Furthermore, such an optoelectronic pressure sensor can detect external pressure over a wide and easily adaptable pressure range.

[0027] According to various unclaimed examples, the first spacer layer 112 may comprise the elastic material, for example, an elastic polymer, and the second spacer layer 115 may comprise a non-elastic material, for example, a non-elastic polymer or any other suitable (e.g., non-polymer) material. A difference between an elastic material and a non-elastic material may be defined by their elastic moduli differing by one or more orders of magnitude.

[0028] As a result, the optoelectronic pressure sensor 100 can have a first compressible (e.g., flexible or expandable) cavity 110A and a second non-compressible (e.g., non-flexible or non-expandable) cavity 110B. The non-compressible cavity 110B can prevent the resonance peaks from crossing under deformation of the compressible cavity. This can improve the sensor resolution. Furthermore, the measuring range and the measuring accuracy of the optoelectronic pressure sensor 100 can be increased by finer features and more varied periodicity of the features. For example, with mode order 1, a relative phase p1 of signals (with respect to the recurring shape) and with mode order 2, a relative phase p2 (in the temporal tracking or from the calibration curve of the sensor) can be determined, whereby it can then be seen which relative phase p and sensor signals, for example,s1 and s2 belong together with respect to a certain thickness (=deformation state = applied pressure) of the compressible layer.

[0029] According to various embodiments, at least one property of the optical resonator 110 can be varied when the first spacer layer 112 is compressed (due to an external mechanical pressure) and / or expanded. Illustratively, the optical resonator 110 can be varied due to a change in thickness (Δ 112 , Δ 115 ) of the first spacer layer 111 and / or the second spacer layer 115 may be pressure-sensitive. The property of the optical resonator 110 that can be varied when the first spacer layer 112 is compressed or expanded may, for example, be the wavelength of the electromagnetic radiation that preferably forms in the optical resonator 110.

[0030] The electromagnetic radiation that can be captured and / or formed between the first mirror layer structure 111 and the second mirror layer structure 114 can be reflected, for example, by more than 90% by the at least two dielectric mirror layer structures 112, 114. As a result, at least one mode can form depending on the total layer thickness of the optical resonator 110.

[0031] Alternatively, according to various embodiments, the first spacer layer 112 may comprise a first elastic material and the second spacer layer 112 may comprise a second elastic material different from the first elastic material, as shown in Fig. 2. For example, the second elastic material can be designed and / or configured such that it can have a different compression modulus than the first elastic material.

[0032] According to various embodiments, the first elastic material can, for example, have a compression modulus in a range from 0.1 Pa to 10 MPa, and the second elastic material can, for example, have a compression modulus in a range from 100 MPa to 5 GPa. The layers can be compressed to different degrees, and after one layer is fully compressed at higher pressures, the second layer can continue to react.

[0033] This may enable the optoelectronic pressure sensor to be able to detect a wide range of different pressure ranges.

[0034] Illustratively, the optical resonator 110 can be changed due to a change in thickness (Δ 112 , Δ 115) of the first spacer layer 111 and / or the second spacer layer 115 may be pressure-sensitive, and the wavelengths of the electromagnetic radiation preferably formed in the optical resonator 110 may exit the optical resonator 110, wherein at least a portion of the exited electromagnetic radiation may be detected by the optical sensor 140.

[0035] According to various embodiments, the first spacer layer 112 and / or the second spacer layer 115 can be formed and / or configured in the form of a continuous layer. The first spacer layer 112 and / or the second spacer layer 115 can have a surface that can form a substantially smooth interface between the first spacer layer 112 and the first mirror layer structure 111 and / or the second mirror layer structure 114, or between the second spacer layer 115 and the second mirror layer structure 114 and / or the third mirror layer structure 116.

[0036] Alternatively, the first spacer layer 112 and / or the second spacer layer 115 can be designed and / or configured according to various embodiments such that a recess, for example an air recess, can be formed between the first mirror layer structure 111 and the second mirror layer structure 114 or between the second mirror layer structure 114 and the third mirror layer structure 116, as shown for example in Fig. 2. The first spacer layer 112 and / or the second spacer layer 115 can be formed, for example, in the form of at least two strips, wherein the at least two strips can be arranged parallel to one another, for example. Alternatively or additionally, the first spacer layer 112 and / or the second spacer layer 115 can be formed, for example, in the form of a ring.

[0037] According to various embodiments, the respective mirror layer structures 111, 114, 116 may comprise one or more dielectric mirror layers.

[0038] According to various embodiments, the optical resonator 110 may further comprise a spacer layer 113, which may be arranged between the first mirror layer structure 111 and the second mirror layer structure 114 such that the compression of the first spacer layer 112 may be limited to a predefined compression state.

[0039] The radiation source 120 can be arranged adjacent to the optical resonator 110 (e.g., on the first mirror layer structure 111). For example, the radiation source 120 can be arranged outside the optical resonator 110, for example, on a side of the optical resonator 110 opposite the side on which the optical sensor 140 is arranged. The optical resonator 110 and the radiation source 120 can be configured such that the electromagnetic radiation 120e (e.g., light) generated by the radiation source 120 can be coupled and / or introduced into the optical resonator 110.

[0040] According to various embodiments, the radiation source 120 can have at least two electrodes and an emission layer arranged between the at least two electrodes for generating the electromagnetic radiation. The radiation source 120 can be, for example, an LED layer stack or an OLED (organic light-emitting diode) layer stack.

[0041] According to various embodiments, the optical sensor 140 may be configured such that the generated electrical signal (e.g., a generated electrical voltage and / or a generated electrical current) V out / I outcan change when the wavelength of the electromagnetic radiation incident on the optical sensor 140 changes. Clearly, the optical sensor 140 can be wavelength-sensitive. If an external mechanical pressure is exerted on the optoelectronic pressure sensor 100, the distance between the at least two dielectric mirror layer structures 112, 114 from one another can change due to the compression (Δd) of the compressible layer 130. Thus, the preferred wavelength of the electromagnetic radiation that can form in the optical resonator 110 can also change. Clearly, the mechanical pressure exerted on the optoelectronic pressure sensor 100 can be converted into a corresponding electrical signal V by means of the optical sensor 140 (e.g., by means of an organic solar cell layer). out / I out be converted.

[0042] According to various embodiments, the optical sensor 140 can be configured such that a first electrical signal can be generated when the optical resonator 110 has a first property and a second electrical signal can be generated when the optical resonator 110 has a second property, wherein the first signal is different from the second signal. For example, the property can be the wavelength(s) of the electromagnetic radiation that can preferably form in the optical resonator 110.

[0043] According to various embodiments, the optoelectronic pressure sensor 100 may further comprise a transparent carrier 132, which may be configured such that a mechanical pressure that may be exerted on the optical resonator 110 may be transmitted to a lesser extent or not at all to the optical sensor 140. The carrier 132 may be transparent with respect to the wavelengths considered in the resonator and in interaction with the optical sensors.

[0044] According to various embodiments, the transparent carrier 132 can be configured such that the electromagnetic radiation 120e, which can emerge from the optical resonator 110 and / or from the absorbing layer, can be transmitted by the transparent carrier 132 with a high transmittance. The transparent carrier 132 can comprise or consist of glass or glass fiber, for example.

[0045] The transparent carrier 132 in the optoelectronic pressure sensor 100 can have the advantage that the components of the optoelectronic pressure sensor 100, which are separated from the first and / or second spacer layer 112, 115 by the transparent carrier 132, for example, the absorbing layer and / or the optical sensor 140, can have improved mechanical decoupling from the first and / or second spacer layer 112, 115. As a result, the absorbing layer and / or the optical sensor 140 can be more effectively protected from the elastic and / or plastic deformation of the first and / or second spacer layer 112, 115, whereby the service life of the optoelectronic sensor 100 can be increased.

[0046] According to various embodiments, the optoelectronic pressure sensor may further comprise an absorbing layer (not shown). The absorbing layer may, for example, be configured to absorb specific wavelengths. In various embodiments, the wavelength-dependent absorbing layer may be arranged in the optoelectronic pressure sensor 100 such that at least a portion of the electromagnetic radiation that can pass through the optical resonator 110 can be or be absorbed by the wavelength-dependent absorbing layer, for example, before the at least a portion of the electromagnetic radiation can reach the optical sensor 140 and / or be detected by the optical sensor 140.

[0047] The absorbing layer in the optoelectronic pressure sensor can allow the transmission spectrum of the electromagnetic radiation that can be detected by the optical sensor 140 to be modified such that the gradient of the peak intensities is enhanced as a function of the wavelength change. This can increase the sensitivity of the optoelectronic pressure sensor to pressure changes, and thus reduce the requirements for the optical sensor 140 regarding sensitivity to wavelength shifts and / or changes in wavelength intensity.

[0048] According to various embodiments, the absorbing layer may comprise or consist of a polymeric material. For example, the absorbing layer may be a layer consisting of an organic absorber molecule.

[0049] According to various embodiments, the absorbing layer can be arranged within the optical resonator 110. For example, in the optoelectronic pressure sensor, the absorbing layer can be arranged between the first mirror layer structure 111 and the second mirror layer structure 114 and / or between the second mirror layer structure 114 and the third mirror layer structure 116. For example, the absorbing layer can be arranged between a dielectric mirror layer structure 112, 114 of the at least two dielectric mirror layer structures 112, 114 and the compressible layer 130. The absorbing layer can, for example, be in direct (physical) contact with one of the mirror layer structures 111, 114, 116.

[0050] According to various embodiments, the absorbing layer can be arranged outside the optical resonator 110. For example, in the optoelectronic pressure sensor, the absorbing layer can be arranged between the optical resonator 110 and the optical sensor 140 in various embodiments.

[0051] This can make it possible to reduce or prevent the transfer of elastic and / or plastic deformation of the first and / or second spacer layer, which can occur due to the external mechanical pressure exerted on the optoelectronic pressure sensor by compressing or expanding the first and / or second spacer layer, to the absorbing layer. This can increase the service life of the optoelectronic pressure sensor.

[0052] Fig. 3A and Fig. 3B each illustrates a graph of an exemplary characteristic curve of an optoelectronic pressure sensor according to various embodiments. The transmissivity for different wavelengths is plotted relative to a change in the thickness of the first spacer layer 112 while maintaining the same thickness of the second spacer layer 115 (referred to as the variation distance).

[0053] According to various embodiments, the resonance wavelengths of the different modes (defined by the first and second spacer layers 112, 115 or defined by the respective distance of the mirror layer structures 111, 114, 116 from one another) can be in such a relationship that they completely or partially overlap, whereby possibly avoided crossings of the resonance peaks can arise under deformation of the compressible cavity.

[0054] The measurement of the behavior of light can be done, for example, with narrowband photodiodes (see Fig. 4) are carried out, each covering a defined spectral range. Especially in the presence of numerous transmitted modes, their wavelength dependence differs depending on the mirror layer structure spacing (increase in wavelength depends on the mirror layer structure spacing), as shown in Fig. 3 can be seen. The increase in wavelength depending on the mirror layer structure distance reduces with increasing distance of the first mirror layer structure 111 from the second mirror layer structure 114, for example, while the distance of the second mirror layer structure 114 from the third mirror layer structure 116 remains constant. Thus, for example, calibration lines (see Fig. 5) which relate the wavelength change of the modes to the mode order and the mirror layer spacing.

[0055] Fig. 4 illustrates an exemplary measurement of a transmission spectrum 400 of an optoelectronic pressure sensor, according to various embodiments. The exemplary spectral ranges 410, 420 can be measured using corresponding photodiodes (adapted to the spectral range, e.g., using optical filters or other adaptations). A deformation of the compressible cavity or a change in the mirror layer structure spacing leads to specific changes in the intensities of the measured spectral ranges 410, 420, so that an evaluation of a property represented by the compression of the optoelectronic pressure sensor (e.g., pressure, vibration, weight, etc.) is possible based on the optical measurements.

[0056] Fig. Figure 5 illustrates various calibration curves of an optoelectronic pressure sensor according to various embodiments. The calibration curves (in this case, straight lines) are measured for different spectra and extrapolated mathematically. Each calibration curve shows the relationship between the wavelength change of a corresponding optical mode and the change in the mirror layer structure spacing.

[0057] According to various embodiments, for example, a periodic (e.g., electrical) signal can be output depending on the mirror layer spacing for respective spectral ranges (one or more spectral ranges) that are cumulatively detected by an optical sensor (e.g., a photodiode). The periodicity of different signals and their respective phases relative to one another can differ depending on the number of modes, mode order, and compression state. For example, it is possible to record the signal in the different optical sensors over time and thereby draw conclusions about the vibration behavior of a component to which the optoelectronic pressure sensor is attached.Due to the different periodicity of the signals, it is also possible to use individual measurements with a suitable number of spectral windows to determine the distance between the mirror layers and thus, based on the mechanical properties of the layer stack (e.g., Young's modulus, bulk modulus), the applied pressure. This allows differential pressures to be determined at which the optical path length change in the sensor is so large that modes of different orders occupy the same wavelength over the time course of the compression. This is exemplified in . Fig. 5 for two different sensors (state 1 and state 2). While in both cases a mode of one order lies in the same wavelength range, the modes of another order differ in the respective wavelength for state 1 and state 2. Thus, when evaluated with, for example, two narrowband detectors, different signals are output, allowing compressions across multiple mode orders to be distinguished. This also makes the sensor suitable for use as an array for weighing loads by evaluating the local pressures across a suitable area or structure.

[0058] The optical sensor (e.g. a photodiode) can be configured to integrate intensity over the entire spectral range for which the optical sensor is photosensitive.

[0059] As in Fig. As shown schematically in Figure 5, a first state (state 1) can be characterized by a first spectrum (spectrum 1) (see vertical section with solid line), a second state (state 2) can be characterized by a second spectrum (spectrum 2) (dashed vertical line). The spectra can be characterized, for example, by the fact that, as in Fig. 5 In each spectrum, one mode is located at approximately 870 nm (Mode 0), but the spectra differ in Mode 1 (approximately 905 nm) and Mode 2 (approximately 910 nm). Thus, by appropriately selecting spectral windows when measuring the spectra (overlap between the spectrum transmitted through the stack and the sensitivity spectrum of the optical sensor), the compression states of the stack can be determined, and thus the applied pressure can be determined.

[0060] As in Fig. As shown schematically in Figure 5, the unique assignment of the sensor signal constellation to a specific compression state allows the fatigue of the layer stack to be detected by comparing the zero-load signals at different times. Since the relative intensity of the mode peaks follows a fixed curve for different wavelengths, the sensor signals from the optical sensors can be evaluated as relative values. This allows, for example, fluctuations in the brightness of the radiation source caused by production or the operating environment to be compensated.

[0061] Fig. 6 illustrates a graphic showing an embodiment for an evaluation of one or more periodic sensor signals (sensor signals I(D1) and I(D2)) under (e.g. continuous) change of the mirror layer distance of an optoelectronic pressure sensor.

[0062] The signals I of the detectors D1 and D2 (e.g. a fixed mode and a flexible mode) have a different periodicity due to the mode behavior.

[0063] According to various embodiments, the layer stack can be sensitive to different pressures depending on the application by selecting the compressible materials. Materials with suitable stress-strain curves can also be selected to adjust the relative layer thickness change. For example, materials with sublinear stress-strain curves can be used for this purpose, so that for high compressive pressures, the relative compression increases and a stronger wavelength change is achieved with a lower number of modes.

[0064] According to various embodiments, different materials with different compression behaviors can also be used in the layer stacks, making it possible, for example, to detect pressures over a larger area, since, for example, even when a spacer layer is fully compressed, another spacer layer with a higher compression modulus can be used to generate a differential signal. In this case, the layer stack can be designed, for example, such that the softer spacer layer is protected by an incompressible spacer and cannot be compressed beyond a certain degree of compression (see, for example, Fig. 2).

[0065] The compressible spacer layer may not cover the entire substrate, but may, for example, keep the optical path free for the measurement in order to avoid disturbances caused by surface roughness of the compressible spacer layer and to avoid effects caused by changes in the refractive index at different pressures (see, for example, Fig. 2).

[0066] According to various embodiments, the optoelectronic pressure sensor or a method for operating the optoelectronic pressure sensor can comprise interpolating multiple optical modes and using the interpolated optical modes to evaluate a measured value. This can, for example, significantly expand the measurable pressure range.

[0067] According to various embodiments, the optoelectronic pressure sensor or a method for operating the optoelectronic pressure sensor may comprise using a plurality of coupled modes to determine a hysteresis of the sensor (see, for example, Fig. 6).

[0068] According to various embodiments, an output signal of the optoelectronic pressure sensor (e.g. stored as data) can be used to detect a sensor change (e.g. material fatigue).

[0069] According to various embodiments, two output signals of the optoelectronic pressure sensor can be used to detect the exact pressure change and to determine the mode in which the measurement is taken.

[0070] Some examples are described below which relate to what is described herein and shown in the figures.

[0071] Example 1 is an optoelectronic pressure sensor 100, the optoelectronic pressure sensor comprising an optical resonator; the optical resonator 110 comprising: a first mirror layer structure 111, a second mirror layer structure 114, a third mirror layer structure 116, and a first spacer layer 112 arranged between the first mirror layer structure 111 and the second mirror layer structure 114, and a second spacer layer 115 arranged between the second mirror layer structure 114 and the third mirror layer structure 116, wherein at least the first spacer layer 112 or the second spacer layer 115 comprises an elastic material and is configured such that at least one property of the optical resonator 110 is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator 110;at least one radiation source 120 for generating electromagnetic radiation 120e, wherein the optical resonator 110 and the radiation source 120 are configured such that the generated electromagnetic radiation 120e is coupled into the optical resonator 110; and at least one optical sensor 140 arranged outside the optical resonator 110 for detecting electromagnetic radiation exiting the optical resonator 110. The first spacer layer 112 comprises a first elastic material, and the second spacer layer 112 comprises a second elastic material different from the first elastic material.

[0072] In Example 2, the optoelectronic pressure sensor according to Example 1 can further optionally be configured such that the respective mirror layer structures 111, 114, 116 have one or more dielectric mirror layers.

[0073] In Example 3, the optoelectronic pressure sensor according to Examples 1 or 2 may further optionally be configured such that the optical resonator 110 further comprises a spacer layer 113 arranged between the first mirror layer structure 111 and the second mirror layer structure 114 such that the compression of the first spacer layer 112 is limited to a predefined compression state.

[0074] In Example 4, the optoelectronic pressure sensor according to Example 3 can further optionally be configured such that the first spacer layer and the second spacer layer 115 are arranged and formed in the optical resonator 110 such that, when the first spacer layer 112 has reached the predefined compression state due to an external pressure acting on the optical resonator 110 in a first pressure range, the at least one property of the optical resonator 110 is further varied when the second spacer layer 115 is compressed and / or expanded due to an external pressure acting on the optical resonator 110 in a second pressure range.

[0075] Example 5 is an optoelectronic pressure sensor comprising: an optical resonator 110 with one or more resonance structures 110A, 110B, wherein each of the one or more resonance structures 110A, 110B is formed by a respective pair of mirror layer structures 111 / 114, 114 / 116 and a spacer layer 112, 115 arranged within the pair of mirror layer structures, wherein at least one spacer layer 112, 115 of the one or more resonance structures 111 / 114, 114 / 116 comprises an elastic material and is configured such that at least one property of the optical resonator 110 is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator 110;at least one radiation source 120 for generating electromagnetic radiation 120e, wherein the optical resonator 110 and the radiation source 120 are configured such that the generated electromagnetic radiation 120e is coupled into the optical resonator 110; a sensor arrangement 140 configured to detect electromagnetic radiation emerging from the optical resonator 110 in the first wavelength range and in the second wavelength range, to output a first measurement signal representing an intensity of the detected electromagnetic radiation in the first wavelength range, and a second measurement signal representing an intensity of the detected electromagnetic radiation in the second wavelength range, to determine an external pressure based on the first measurement signal and the second measurement signal;and an evaluation device 150 which is configured to calculate an intensity difference between the first measurement signal and the second measurement signal, wherein the intensity difference represents an absolute pressure value of an external pressure acting on the optical resonator 110.;

[0076] Example 6 is an optoelectronic pressure sensor comprising: an optical resonator 110 with one or more resonance structures 110A, 110B, wherein each of the one or more resonance structures 110A, 110B is formed by a respective pair of mirror layer structures 111 / 114, 114 / 116 and a spacer layer 112, 115 arranged within the pair of mirror layer structures, wherein at least one spacer layer 112, 115 of the one or more resonance structures 111 / 114, 114 / 116 comprises an elastic material and is configured such that at least one property of the optical resonator 110 is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator 110;at least one radiation source 120 for generating electromagnetic radiation 120e, wherein the optical resonator 110 and the radiation source 120 are configured such that the generated electromagnetic radiation 120e is coupled into the optical resonator 110; a sensor arrangement 140 configured to detect electromagnetic radiation emerging from the optical resonator 110 in the first wavelength range and in the second wavelength range, to output a first measurement signal representing an intensity of the detected electromagnetic radiation in the first wavelength range and a second measurement signal representing an intensity of the detected electromagnetic radiation in the second wavelength range, and to determine an external pressure acting on the optical resonator 110 based on the first measurement signal and the second measurement signal;and an evaluation device 150 which is configured to detect a temporal intensity difference between the first measurement signal and the second measurement signal, wherein the temporal intensity difference represents a temporal absolute pressure change of an external pressure acting on the optical resonator 110.;

Claims

[1] Optoelectronic pressure sensor (100) comprising: an optical resonator (110), the optical resonator (110) comprising: a first mirror layer structure (111), a second mirror layer structure (114), a third mirror layer structure (116) and a first spacer layer (112) arranged between the first mirror layer structure (111) and the second mirror layer structure (114), and a second spacer layer (115) arranged between the second mirror layer structure (114) and the third mirror layer structure (116), wherein at least the first spacer layer (112) or the second spacer layer (115) comprises an elastic material and is configured such that at least one property of the optical resonator (110) is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator (110); at least one radiation source (120) for generating electromagnetic radiation (120e), wherein the optical resonator (110) and the radiation source (120) are configured such that the generated electromagnetic radiation (120e) is coupled into the optical resonator (110); and at least one optical sensor (140) for detecting electromagnetic radiation coupled into the optical resonator (110); wherein the first spacer layer (112) comprises a first elastic material and wherein the second spacer layer (115) comprises a second elastic material different from the first elastic material. [2] Optoelectronic pressure sensor (100) according to claim 1, wherein the respective mirror layer structures (111, 114, 116) comprise one or more dielectric mirror layers. [3] Optoelectronic pressure sensor (100) according to one of claims 1 or 2, wherein the optical resonator (110) further comprises a spacer layer (113) arranged between the first mirror layer structure (111) and the second mirror layer structure (114) such that the compression of the first spacer layer (112) is limited to a predefined compression state. [4] Optoelectronic pressure sensor (100) according to claim 3, wherein the first spacer layer (112) and the second spacer layer (115) are arranged and formed in the optical resonator (110) such that, when the first spacer layer (112) has reached the predefined compression state due to an external pressure acting on the optical resonator (110) in a first pressure range, the at least one property of the optical resonator (110) is further varied when the second spacer layer (115) is compressed and / or expanded due to an external pressure acting on the optical resonator (110) in a second pressure range. [5] Optoelectronic pressure sensor (100) comprising: an optical resonator (110) having one or more resonance structures (110A, 110B), wherein each of the one or more resonance structures (110A, 110B) is formed by a respective pair of mirror layer structures (111 / 114, 114 / 116) and a spacer layer (112, 115) arranged within the pair of mirror layer structures, wherein at least one spacer layer (112, 115) of the one or more resonance structures (110A, 110B) comprises an elastic material and is configured such that at least one property of the optical resonator (110) is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator (110); at least one radiation source (120) for generating electromagnetic radiation (120e), wherein the optical resonator (110) and the radiation source (120) are arranged such that the generated electromagnetic radiation (120e) is coupled into the optical resonator (110); a sensor arrangement configured to detect electromagnetic radiation, electromagnetic radiation coupled into the optical resonator (110), in a first wavelength range and in a second wavelength range, to output a first measurement signal representing an intensity of the detected electromagnetic radiation in the first wavelength range, and a second measurement signal representing an intensity of the detected electromagnetic radiation in the second wavelength range, to determine an external pressure based on the first measurement signal and the second measurement signal; and an evaluation device (150) which is configured to calculate an intensity difference between the first measurement signal and the second measurement signal, wherein the intensity difference represents an absolute pressure value of an external pressure acting on the optical resonator (110). [6] Optoelectronic pressure sensor (100) comprising: an optical resonator (110) having one or more resonance structures (110A, 110B), wherein each of the one or more resonance structures (110A, 110B) is formed by a respective pair of mirror layer structures (111 / 114, 114 / 116) and a spacer layer (112, 115) arranged within the pair of mirror layer structures, wherein at least one spacer layer (112, 115) of the one or more resonance structures (110A, 110B) comprises an elastic material and is configured such that at least one property of the optical resonator (110) is varied when the elastic material is compressed and / or expanded due to an external pressure acting on the optical resonator (110); at least one radiation source (120) for generating electromagnetic radiation (120e), wherein the optical resonator (110) and the radiation source (120) are arranged such that the generated electromagnetic radiation (120e) is coupled into the optical resonator (110); a sensor arrangement configured to detect electromagnetic radiation, electromagnetic radiation coupled into the optical resonator (110), in a first wavelength range and in a second wavelength range, to output a first measurement signal representing an intensity of the detected electromagnetic radiation in the first wavelength range, and a second measurement signal representing an intensity of the detected electromagnetic radiation in the second wavelength range, to determine an external pressure acting on the optical resonator (110) based on the first measurement signal and the second measurement signal; and an evaluation device (150) which is configured to detect a temporal intensity difference between the first measurement signal and the second measurement signal, wherein the temporal intensity difference represents a temporal absolute pressure change of an external pressure acting on the optical resonator (110). [7] Optoelectronic pressure sensor (100) according to claim 6, wherein the evaluation device (150) is configured to detect the temporal intensity difference based on a temporal profile of oscillation frequencies, preferably a temporal profile of oscillation frequencies of the first measurement signal and / or the second measurement signal.

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