EP3304146A1

EP3304146A1 - Optical sensor for measuring trace components in liquids and/or gases

Info

Publication number: EP3304146A1
Application number: EP16726280.7A
Authority: EP
Inventors: Kai-Peter Stamer
Original assignee: Bartec Benke GmbH
Current assignee: Bartec Benke GmbH
Priority date: 2015-06-02
Filing date: 2016-05-27
Publication date: 2018-04-11
Also published as: WO2016192845A1; DE102015007206A1

Abstract

The optical sensor serves to measure trace components in liquids and/or gases and has at least one optical resonator (2) which has at least one porous layer, the porous layers whereof serve to receive moisture particles. The resonator (2) is a ring resonator, with which at least one optical waveguide (1) is associated. Light is fed into the waveguide (1), which is partially decoupled into the ring resonator (2). Interference with the waveguide (1) arises in the ring resonator (2) because of the partially very high fineness thereof, into which waveguide a light spectrum is radiated. A comb of wave length minima can be filtered out of the transmission spectrum. If trace components are deposited in the pores of the ring resonator (2), the refractive index and the optical path length are changed, which leads to wavelength shift of the filtered wavelength minima. The amount of trace components can be determined from the wavelength shift.

Description

OPTICAL SENSOR FOR MEASURING TRACE COMPONENTS IN LIQUIDS AND / OR GASES

The invention relates to an optical sensor according to the preamble of claim 1.

Optical sensors are used to measure trace moisture in gases and liquids. They consist of several porous and dielectric layers, in the pores of which any moisture particles are deposited. If light is radiated by the moisture sensor, the refractive index of the incident light changes as a result of the embedded moisture particles. This leads to a wavelength shift in the optical sensor which is proportional to the humidity in the medium to be measured. From the wavelength shift, the content of moisture in the medium to be measured can be detected.

The measuring principle is based on the basic principle of a Fabry-Perot interferometer. However, for many applications it has too slow a response to changes in humidity. The cause of this relatively slow reaction behavior lies in the structure of the layer system and in the thicknesses and porosities of the individual layers. The thicker the layer system, the slower it dries in a gas stream. On the other hand, the thickness of the layer system is crucial for the finesse of the Fabry-Perot interferometer and thus also determines the half-width at the wavelength minimum. This significantly influences the accuracy of the signal analysis.

The known optical sensor has a layer system of eleven alternating low and high refractive porous layers, which consist of S1O2, Zr0 ₂ . The layer system has a total thickness of more as 2um. Such a design of the optical sensor represents a compromise between the smallest possible thickness and a high finesse. The response times measured with such an optical sensor at a dew point change between + 10 ° C and -60 ° C at a gas temperature of 30 ° C vary due to the different porosity of the layers between 1 and 7 hours.

The invention has the object of providing the generic optical sensor in such a way that the measurement times are significantly reduced without affecting the measurement accuracy.

This object is achieved in the generic optical sensor according to the invention with the characterizing features of claim 1.

In the sensor according to the invention, the resonator is formed by a ring resonator. In the ring resonator due to its sometimes very high finesse interference with the waveguide, in which a light spectrum is irradiated. From the transmission spectrum a comb of wavelength minima can be filtered out. If trace constituents are deposited in the pores of the ring resonator, the refractive index and thus the optical path length are changed. This leads to a wavelength shift of the wavelength minima filtered out. From the wavelength shift can be determined in a known manner, the content of trace constituents in the medium to be measured with high accuracy. With the sensor according to the invention results compared to the known sensor a greatly reduced thickness of the moisture layer, whereby a much faster reaction time can be made possible.

Generally, a modems spectrum is filtered out of the transmission spectrum, which can be used to determine the content of trace constituents. The shift of the wavelength minima offers the possibility to calibrate highly accurate gas characteristics. The ring resonator is self-contained, but may have any outline shape.

In an advantageous embodiment, the ring resonator is assigned a further waveguide. The modems spectrum or the discrete wavelength maxima running in the ring resonator are partially decoupled into it. The decoupled light can be fed separately to a spectrometer, with which the decoupled light is evaluated.

In an advantageous embodiment, a plurality of ring resonators are arranged one behind the other along the waveguide. Such a design allows a better measurement of the trace moisture content. Also, the plurality of ring resonators may be formed so that they have different sized pores, so that when several ring resonators and different trace constituents can be detected in a measurement process. The pore size is adapted to the trace constituent to be detected. Thus, for example, by corresponding pore size of the ring resonators simultaneously different concentrations of H ₂ 0 and / or other molecules can be detected in sample gases.

In an advantageous embodiment, the plurality of ring resonators may be located between the two waveguides, so that the ring resonators at least partially decouple the coupled light in the other waveguide. The further waveguide thus makes it possible to add additional discrete wavelength maxima to the mode spectra of the further ring resonators and to feed them to a spectrometer or a similar measuring device.

In a further advantageous embodiment, two adjacent ring resonators are located between the two waveguides. In a further embodiment, a plurality of such annular resonators arranged in pairs may be provided one behind the other between the two waveguides.

The ring resonator (s) and the waveguide (s) may be provided on a carrier. It can be made of glass or crystal, for example.

However, it is also possible for the ring resonator (s) to be located on the carrier while the waveguide (s) are embedded in the carrier. The waveguide is thus protected in the sensor.

In an advantageous embodiment, the ring resonator (s) may be wholly or partially surrounded by a cladding layer on the outer diameter. This cladding layer is advantageously at least one optical PVD layer. The material of the cladding layer has a refractive index which is smaller than the refractive index of the material of the ring resonator. The cladding layer can be compared to the gas to be measured or the liquid to be measured both as a protective layer and, with a defined pore size, which is smaller than the pore size of the material of the ring resonator, as a filter layer and with a defined pore size, which is greater than the pore size of the material of the ring resonator, serve as a storage layer.

The waveguide may be made of ion-implanted glasses or crystals or PVD optical layers. Such PVD layers may consist, for example, of SiO ₂ , ZrO ₂ , TiO ₂ or TaO ₅ .

Advantageously, the ring resonator on optical PVD layers, for example, S1O2, r0 ₂ , T1O2 or TaOs. could be.

The subject of the application results not only from the subject matter of the individual claims, but also by all the information and features disclosed in the drawings and the description. They are, even if they are not the subject of the claims, as erfindungswesent- borrowed, as far as they are new individually or in combination over the prior art.

Further features of the invention will become apparent from the other claims, the description and the drawings.

The invention is explained below with reference to some embodiments shown in the drawings. Show it

1 shows a schematic representation of a first embodiment of a sensor according to the invention,

FIG. 2 shows wavelength minima filtered out from the transmission spectrum of the sensor according to FIG. 1, FIG.

3 shows a representation corresponding to FIG. 1 of a second embodiment of a sensor according to the invention, FIG.

FIG. 4 shows, in a representation corresponding to FIG. 2, the wavelength minima which are filtered out of the transmission spectrum associated with the sensor according to FIG. 3, FIG.

5 is an enlarged section of the diagram of FIG. 4,

Fig. 6

to

10 further diagrams corresponding to FIG. 5 for explaining a wavelength shift,

Fig. 1 1

to

FIG. 14 in illustrations corresponding to FIG. 1, further embodiments of sensors according to the invention, FIG. 1 5 is a plan view of another embodiment of a sensor according to the invention,

16 is a side view of the sensor of FIG. 15,

17 is a front view of the sensor of FIG. 15,

Fig. 18

to

21 in each case in section further embodiments of sensors according to the invention,

FIG. 22 shows the sensor according to FIGS. 15 to 17, which is connected to an LED light source and a polychromator.

The sensors are used to measure trace moisture or trace gases in gases and / or liquids. For example, the sensor determines the moisture content in natural gas. For this purpose, the sensor protrudes into the natural gas pipeline so that it is detected by the natural gas flowing through it. The sensor is connected to a measuring device (not shown) which detects the signals coming from the sensor and evaluates them in a known manner. The determined moisture content is assigned to a dew point by means of an evaluation unit of the measuring device.

The optical sensor will be described below using the example of a humidity sensor. It can also be designed as a gas sensor with which trace gases in the medium can be detected and measured.

The humidity sensor has in the embodiment of FIG. 1, a ring resonator 2, which serves as an optical measuring medium. The ring resonator is a self-contained waveguide, which in the exemplary embodiment circular shape Has. However, the ring resonator 2 may have any other suitable geometric shape.

The ring resonator 2 has a porous coating, which is preferably at least one PVD layer vapor-deposited on a base support. This porous layer consists for example of Si0 ₂ , Zr0 ₂ or Ta ₂ Os. The porosity of this layer is matched to the trace constituent to be detected. If this trace constituent to be detected is water, then the pores of the porous layer typically have a diameter of about 3 Å. If the medium to be measured contains water, then water molecules are deposited in the pores of the porous layer whose diameter is slightly less than 3 Å , The water molecules incorporated in the porous layer change, as will be described, the refractive index of an incident light, which results in a wavelength shift which is proportional to the moisture content in the medium to be measured.

The light necessary for measuring the moisture content is coupled via a waveguide 1 in the ring resonator 2. The waveguide 1 may be made of suitable materials, such as ion-implanted glasses and crystals, or of PVD optical layers, which may be, for example, SiO ₂ , ZrO ₂ , ΤΊΟ ₂ , Ta ₂ O _5, and the like. In the waveguide 1 8 indicated light is initiated by an arrow. The light source used is preferably LED, which has a long service life, is inexpensive and requires no maintenance. Further sources of light are halogen lamps or, for example, also laser LEDs or laser diode-pumped phosphor layers or pumped TLSaphire.

The thickness of the porous layer is for example some 100 nm. However, this value is not to be understood as limiting. The layer has such a thickness that an optimally fast adaptation to changing moisture conditions in a gas or liquid stream is possible. The ring resonator is a ring waveguide in which a continuous wave is formed due to the total reflection capability of the ring waveguide.

The smallest distance 9 between the waveguide 1 and the ring resonator 2 is the measuring distance, which determines the size of the coupling factor. It is a measure of the decoupling of a portion of the light from the waveguide. 1

The ring resonator 2 partly has a very high finesse F. This has the consequence that arise in the ring resonator 2 interference with the waveguide 1. The proportion of the coupled into the ring resonator 2 portion of the light 8 can be represented in a transmission spectrum, in which the intensity is plotted against the wavelength of the light 8. From this transmission spectrum, the wavelength minima can be filtered out. An example of this is shown in FIG. 2, in which a comb of wavelength minima, which arise during the coupling of the light from the waveguide 1 into the ring resonator 2, have been filtered out of the transmission spectrum.

If there is moisture in the medium to be tested, in this case water, then the water molecules deposit in the porous layer of the ring resonator 2. By the stored water molecules, the refractive index of the light coupled into the ring resonator 2 changes. This leads to a wavelength shift that is proportional to the moisture content in the medium to be measured.

On the basis of the wavelength shift, which is visible in the transmission spectrum or in the filtered-out wavelength minima, the moisture content in the analyst can be determined with high accuracy. This will be explained in more detail with reference to the following embodiment of the sensor.

In the embodiment according to FIG. 3, the waveguide 1 is assigned two ring resonators 2, 3. They are advantageously designed differently and arranged with the measuring distance 9 next to the waveguide 1, in which the light 8 is introduced. In the manner described, a portion of the light is coupled into the ring resonators 2, 3. From the associated transmission spectrum two combs of wavelength minima can be filtered out. The corresponding diagram is shown in FIG. 4.

FIG. 5 shows the wavelength range between 1 .300 and 1 .307 nm from FIG. 4 in an enlarged representation.

FIG. 6 shows, from two ring resonators, in each case a wavelength minimum which has been filtered out of a transmission spectrum which results when water molecules are incorporated into the porous layer of the ring resonator 2 and into the non-porous layer or into the porous layer coated with an impermeable protective layer of the ring resonator 3 get no water molecules. A comparison of FIGS. 5 and 6 shows that, due to the incorporated water molecules, the one wavelength minimum from the ring resonator 2 has shifted from the wavelength 1.301, 45 nm to the wavelength 1.301, 68 nm. This wavelength shift, caused by the stored water molecules, is proportional to the measured moisture in the medium. The wavelength minimum of the ring resonator 3, which is in the exemplary embodiment at a wavelength of 1.301, 1 nm, serves as a reference value and can compensate for temperature influences. The evaluation unit in the measuring device to which the sensor is connected, can determine the dew point and thus the proportion of moisture in the medium to be tested due to the difference between the two wavelength minima and at a known temperature of the medium.

By way of example, the temperature of the medium would, as shown in FIG. 13, comprise another additional ring resonator made of a non-porous layer of a material having a high thermo-optic coefficient dn / dt which differs greatly from the thermo-optical coefficient of the two ring resonators 2 and 3. when a difference value of its wavelength minimum with respect to the reference value of the ring sonators 3 measured and this difference value would be assigned a temperature value based on a calibration curve.

FIGS. 7 to 10 show examples of how the wavelength shift results as a function of the moisture content in the medium to be measured. By way of example, it is shown in FIG. 7 that the two wavelength minima are at a wavelength of 1,300 and 1 .303, 1 nm. If water molecules are deposited in the porous layer of the ring resonator or resonators 2, this leads to a wavelength shift, as can be seen from the diagram according to FIG. 8. Both wavelength minima have shifted to 1, 303.1 and 1, 303.4 nm.

With an even greater proportion of water, the wavelength minimum in FIG. 9 shifts to a wavelength of 1.303.65 nm. With an even greater water content, this wavelength minimum shifts to a wavelength of almost 1.304 nm (FIG. 10).

These examples show that the wavelength shift is detected with high accuracy and accordingly the moisture content in the medium to be measured can be determined very accurately.

Fig. 1 1 shows a further embodiment of a sensor. In contrast to the previous embodiments, two waveguides 1, 5 are provided, between which the ring resonator 2 is located. Both waveguides 1, 5 are advantageously made of the same material, such as of ion-implanted glasses or crystals or of optical PVD layers, which consist for example of S1O2, Zr02, Ti0 ₂ or Ta ₂ Os. In the waveguide 1, the light 8 is introduced, which is partially coupled in the manner described in the ring resonator 2. The mode spectra or discrete wavelength maxima forming in the ring resonator 2 are decoupled into the waveguide 5, which forwards the coupled-out light 8 '. The decoupled and passed through the waveguide 5 light 8 'can be separately fed to a spectrometer. The two waveguides 1, 5 are advantageously arranged with the same measuring distance 9 next to the ring resonator 2.

From the transmission spectrum resulting from the coupling of the light 8 from the waveguide 1 into the ring resonator 2, the moisture content can be determined in the manner described when the wavelength shift occurs.

In the embodiment according to FIG. 12, in turn, the two waveguides 1, 5 are provided, of which the waveguide 1 couples the light 8 into the ring resonator 2, as has been described with reference to the preceding exemplary embodiments. In addition to the ring resonator 2, there is a second ring resonator 10, which lies with the measuring distance 9 next to the ring resonator 2. As a result, light from the ring resonator 2 can be coupled into the ring resonator 10. The waveguide 5 ensures that the mode spectrum or the discrete wavelength maxima running in the ring resonator 10 are coupled out into the waveguide 5. The decoupled light 8 'can in turn be supplied to a spectrometer.

The use of two adjacent ring resonators 2, 10 offers the advantage that the second ring resonator 10 could be dimensioned to be e.g. only every second wavelength maximum from the ring resonator 2 picks up and in this way enables a doubled free spectral range. This principle is helpful if the wavelength shift between maximum dryness and maximum humidity is greater than the free spectral range in the first ring resonator 2. In this way, the entire humidity range can be detected without ambiguity.

Fig. 13 shows the possibility to arrange a plurality of ring resonators 2 to 4 in a row between the two waveguides 1 and 5. The light 8, which is supplied to the waveguide 1, in the manner described in the respective ring resonators 2 to 4 are coupled and coupled into the waveguide 5. The decoupled light 8 'can be supplied to the waveguide 5, for example, the spectrometer. In addition, in this embodiment, the waveguide 5 additionally serves to add further discrete wavelength maxima from the mode spectra of the various ring resonators 2 to 4. In this way, for example, several to many ring resonators can be used with different pore sizes from fine to coarse and thereby different gases are distinguished from each other. Also, a ring could act as a reference signal that would compensate for interference, and a ring made of another material with a high thermo-optic coefficient, which could serve to determine the gas temperature.

In FIG. 13, the points indicated between the ring resonators 3 and 4 indicate that the number of ring resonators can vary depending on the application of the sensor.

In the embodiment according to FIG. 14, the ring resonators 2 to 4 and 10 to 12 are provided in pairs between the two waveguides 1, 5. The light 8 supplied via the waveguide 1 is coupled into the respective ring resonators 2 to 4. This coupled light is in turn coupled into the ring resonators 10 to 12, which decouple the light in the waveguide 5. This coupled-out light 8 'is in turn supplied to a spectrometer, for example. As explained in the exemplary embodiment according to FIG. 13, the wavelength maxima from the mode spectra of the individual ring resonators 10 to 12 are fed to the waveguide 5, which thus adds up these wavelength maxima.

Also in this embodiment, as indicated by the points, further ring resonators can be provided in both vertical rows, depending on the application of the sensor. FIGS. 15 to 17 show a concrete embodiment of a sensor. The waveguide 1 is located in a carrier 13, which may consist for example of glass or crystal. The two ends 14, 15 of the waveguide 1 open into an end face 16 of the carrier 13. The adjoining the ends 14, 15 sections 17, 18 of the waveguide 1 are initially parallel to each other and go over a loop portion 19 into each other. The waveguide 1 is located at a short distance below the upper side 20 of the carrier 13th

On the carrier top 20, the two ring resonators 3 and 4 are arranged, which are located at the level of the loop portion 19 of the waveguide 1, viewed in plan view of the sensor. The ring resonators 3, 4 are located next to one another at a distance and are arranged with respect to the waveguide 1 so that they overlap, as seen in plan view according to FIG. 15 (see also FIG. 16).

The light 8 fed into the waveguide 1 is coupled into the ring resonators 3, 4 in the manner described. The ring resonators 3, 4, since they are arranged on the upper side 20 of the carrier 13, come into contact with the medium to be measured. The molecules of the moisture possibly contained in the medium are deposited in the porous layer of at least one ring resonator 3 and / or 4 and lead in the manner described to a wavelength shift of the wavelength minima, as has been explained with reference to the previous embodiments.

FIG. 18 shows a section through the sensor according to FIG. 11. The two waveguides 1 and 5, between which the ring resonator 2 is located, are mounted on a carrier 6, which can consist of glass or crystal by way of example. The waveguides 1, 5 and the ring resonator 2 can be very easily applied to the top 21 of the carrier 6. During the measurement, the sensor is arranged so that the medium to be measured comes into contact with the ring resonator 2, so that moisture molecules can settle in the pores of the porous layer of the ring resonator 2. The embodiment according to FIG. 19 differs from the previous embodiment in that the two waveguides 1, 5 are arranged not at the upper side, but at a short distance from the upper side 21 within the carrier 6. The distance between the waveguides 1, 5 and the ring resonator 2 is chosen so that the light fed in via the waveguide 1 can be coupled into the ring resonator 2 and coupled out of the ring resonator into the waveguide 5. The measuring distance between the waveguides 1, 5 and the ring resonator 2 is present in this case perpendicular to the carrier top 21. The position of the waveguides 1, 5 is chosen so that they lie below the ring resonator 2 in section.

FIG. 20 shows an embodiment of a sensor which basically has the same construction as the sensor according to FIG. 19. The ring resonator 2 is surrounded by a cladding layer 7, which consists of a material which has a smaller refractive index n than the coated ring resonator 2. The cladding layer 7 is advantageously an optical PVD layer. It can for example consist of SiO ₂ , which has a refractive index n of 1.45. The ring resonator 2 can in this case for example consist of ZrO ₂ with a refractive index n of 2.14.

The cladding layer 7 may completely or partially surround the ring resonator 2. The cladding layer 7 can serve both as a protective layer and as a filter layer or as an intercalation layer relative to the gas to be measured or the liquid to be measured. In the case of a filter layer, the cladding layer 7 has a defined pore size which is smaller than the pore size of the material of the ring resonator 2. In the case of an intercalation layer, the cladding layer 7 has a defined pore size which is greater than the pore size of the material of the ring resonator 2.

The embodiment according to FIGS. 18 to 20 may be provided in the case of the sensors which has the two waveguides 1, 5 located on either side of the ring resonator or resonators (FIGS. 1 to 14). Fig. 21 shows a sensor with a layer structure. The carrier 6 is formed in contrast to the embodiments according to FIGS. 18 to 20 as a ring. On the support 6, the ring resonator 2 is fixed, which is surrounded according to the embodiment of FIG. 20 of the cladding layer 7. In addition, the waveguide 1 is fixed on the carrier 6. It is embedded in the cladding layer 7, which surrounds the ring resonator 2. The waveguide 1 and the ring resonator 2 with the cladding layer 7 lie in a common plane and form a first layer 22, which is fastened on the carrier 6.

On the layer 22 with the interposition of an insulating layer 23, a second layer 24 is applied, which is the same as the first layer 22. The insulating layer 23 prevents the two layers 22, 24 interfere with each other during the measuring process.

In this way, 23 more layers 25, 26 are applied to each other on the support 6 with the interposition of an insulating layer. The dots above the sensor indicate that additional layers may be provided.

In the embodiments with multiple ring resonators, it is possible to tune the ring resonators to different trace constituents. Thus, for example, with the help of one ring resonator water and with the help of the other ring resonator ammonia can be detected in the medium in one measurement. The pore size is adapted to the molecular size of the trace constituents to be detected. The molecular sizes of some trace constituents are given below:

Water 0.28 nm

Ammonia 0.30 nm

Carbon monoxide 0.32 nm

Carbon dioxide 0.33 nm Hydrogen chloride 0.35 nm

Hydrogen sulfide 0.36 nm

Methanol 0.38 nm

Methyl mercaptan 0.45 nm

The pores of the ring resonator are adapted to the molecular sizes given above so that the corresponding molecules can be deposited in the pores.

The ring resonators 2 in the various layers can be matched to different components to be detected, so that the corresponding trace constituents can be detected in the medium to be measured.

FIG. 22 shows the sensor according to FIGS. 15 to 17 with the waveguide connected to a light source 27. It is in the illustrated embodiment, an LED light source with which the light is introduced into the waveguide 1 via a fiber cable 28. The light fed into the waveguide 1 passes through the waveguide 1 in the manner described and arrives at the end 15 in another fiber cable 29 which supplies the decoupled light to a polychromator 30. The light enters via a slit 31 in the polychromator 30 and reaches a concave grating 32, at which the light is reflected to a CCD detector 33. It is connected to the measuring device (not shown), which evaluates the signals coming from the detector 33 in the manner described.

Claims

claims

1 . Optical sensor for measuring trace constituents in liquids and / or gases, comprising at least one optical resonator, which has at least one porous layer whose pores serve to receive moist particles,

characterized in that the resonator is a ring resonator (2 to 4, 10 to 12), to which at least one optical waveguide (1, 5) is associated, into which light (8) is fed, which enters the ring resonator (2 to 4, 10 to 12) is partially decoupled.

2. Sensor according to claim

characterized in that the ring resonator (2 to 4, 10 to 12) is associated with a further waveguide, in which the in the ring resonator (2 to 4, 10 to 12) coupled light (8) is at least partially decoupled.

3. Sensor according to claim 2,

characterized in that in the further waveguide (1, 5) decoupled light (8 ') is fed to a spectrometer.

4. Sensor according to one of claims 1 to 3,

characterized in that a plurality of ring resonators (2 to 4, 10 to 12) are arranged one behind the other along the waveguide (1, 5).

5. Sensor according to claim 4,

characterized in that the plurality of ring resonators (2 to 4, 10 to 12) at least partially decouple the injected light into the further waveguide (1, 5).

6. Sensor according to one of claims 2 to 5,

characterized in that between the two waveguides (1, 5) two adjacent ring resonators (2 to 4, 10 to 12) are provided.

7. Sensor according to claim 6,

characterized in that a plurality of ring resonators arranged in pairs (2 to 4, 10 to 12) are arranged one behind the other.

8. Sensor according to one of claims 1 to 7,

characterized in that the ring resonator (s) (2 to 4, 10 to 12) and the waveguide (s) (1, 5) are provided on a carrier (6, 13).

9. Sensor according to one of claims 1 to 7,

characterized in that the ring resonator (s) (2 to 4, 10 to 12) are arranged on a carrier (6, 13) and the waveguide (1, 5) is embedded in the carrier (6, 13) / are.

10. Sensor according to one of claims 1 to 9,

characterized in that the / the ring resonator (s) (2 to 4, 10 to 12) is completely or partially surrounded by a cladding layer (7) / whose material has a smaller refractive index (4) than the material of the ring resonator.

11. Sensor according to one of claims 1 to 10,

characterized in that the ring resonator (s) (2 to 4, 10 to 12) is completely or partially surrounded by a filter layer (7), their material for filtering molecules has a smaller pore size than the material of the ring resonator.

Sensor according to one of claims 1 to 10,

characterized in that the ring resonator (s) is / are surrounded by an E storage layer having a corresponding pore size for molecules.

Sensor according to one of claims 1 to 12,

characterized in that the waveguide (1, 5) consists of ion-implanted glasses or crystals or optical PVD layers.

Sensor according to one of claims 1 to 13,

characterized in that the ring resonator (s) (2 to 4, 10 to 2) has at least one optical PVD layer, such as S1O2 Zr0 ₂ , ΤΊΟ2 or Ta0 ₅ .