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1. WO2011000494 - OPTICAL SENSOR AND METHOD FOR DETECTING MOLECULES

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

Claims

1. Optical sensor comprising an optical waveguide (19) into which light can be fed, and at least one light-sensitive element (4) for detecting light coupled out of the waveguide (1) and also various ring resonators (2) , the ring resonators

(2) being coupled optically to the mentioned waveguide (1) and, with the exception of at most one of the ring resonators (2) , each having a device (5) for adjusting resonance frequencies of the respective ring resonator (2) and/or of a coupling between the ring resonator (2) and the waveguide (1) ,

characterized in that

at least two of the ring resonators (2) have different optical lengths in an initial state and are disposed for having their resonance frequencies influenced by different variables to be measured which are specific for each of these ring resonators (2) .

2. Sensor according to claim 1, characterized in that the at least two ring resonators (2) each have one sensitive region which is provided with an active layer which is different for each of these ring resonators (2) for selective immobi- lization of one or more substances to be detected.

3. Sensor according to one of the claims 1 or 2, characterized in that among all ring resonators (2) there is at least one reference resonator with resonance frequencies which are independent of the variables to be measured.

4. Sensor according to one of the claims 1 to 3 , characterized in that it has a light source (3) exhibiting a tunable wavelength for coupling light into the waveguide (1) .

5. Sensor according to one of the claims 1 to 4 , characterized in that the mentioned devices (5) are equipped with a means for varying an effec- tive refractive index of the respective ring resonator (2) .

6. Sensor according to claim 5, characterized in that it has at least one control unit (6) for the devices for adjusting the resonance frequen- cies of the ring resonators (2) , which is configured for modulating the effective refractive indices of the ring resonators (2) with different time dependencies which are specific for each of these ring resonators (2) .

7. Sensor according to one of the claims 1 to 6 , characterized in that the devices (5) for adjusting the resonance frequencies of the ring resonators (5) have a heating element or electrical contacts for applying an electrical field to the respective ring resonator (2) .

8. Sensor according to one of the claims 1 to 7 , characterized in that it has at least a second waveguide (7) which, together with the first- mentioned waveguide (1) , forms a Mach-Zehnder interferometer.

9. Sensor according to claim 8, characterized in that both the first-mentioned waveguide (1) and the second waveguide (7) are coupled optically to a light-sensitive element, respectively, (4) and a difference amplifier (9) is provided for evaluating output signals of these light- sensitive elements (4) .

10. Sensor according to one of the claims 8 or 9, characterized in that the first-mentioned waveguide (1) or the second waveguide (7) is

equipped with a phase shifter (10) .

11. Sensor according to one of the claims 1 to 10, characterized in that it has at least one additional waveguide (1') which is coupled optically to a light-sensitive element and also various additional ring resonators (2) which are coupled optically to the additional waveguide (1'), each of the additional ring resonators (2) being equipped with a device (5) for adjusting their resonance frequencies, and also at least two of the additional ring resonators (2) having dif- ferent optical lengths in an initial state and being designed to have their resonance frequencies influenced by means of different variables to be measured which are specific for each of these ring resonators (2) .

12. Method for detecting molecules of at least one substance by means of a sensor according to one of the claims 1 to 11, in which light is fed into the waveguide (1) , a fluid to be examined is brought in contact with at least two of the ring resonators (2) of the sensor and an output signal of the light-sensitive element (4) is evaluated as a function of wavelength, a shift of resonances in the output signal caused by the fluid being detected and the ring resonator (2) to which this shift can be attributed being identified in such a way that the resonance frequencies of the ring resonators (2) and/or their coupling to the waveguide (1) are varied with different time dependencies which are specific for each of the ring resonators (2) and it is determined which of these time dependencies is correlated with the shifted resonances.

13. Method according to claim 12, characterized in that the devices (5) assigned to the different ring resonators (2) for adjusting the resonance frequencies and/or the coupling between ring resonator (5) and waveguide (1) are actuated successively or periodically with different fre- quencies.

14. Method according to one of the claims 12 or 13, characterized in that the output signal is evaluated as a function of wavelength in that the light fed into the waveguide (1) is tuned over a wavelength range which comprises at least one resonance wavelength of each of the ring resonators (2) .

15. Method according to one of the claims 12 to 14, characterized in that light of two different polarizations is fed into the waveguide (1) and the output signal for each of these polarizations is evaluated independently.