DEVICE AND METHOD FOR DETERMINING A REFRACTIVE INDEX

• US 20170307521A1
• Filed: 10/01/2015
• Published: 10/26/2017
• Est. Priority Date: 10/02/2014
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V., Trustees of Boston University
• Original Assignee: Boston University, Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Schade, Wolfgang, Burgmeier, Jrg, Baumann, Anna Lena, Reinhard, Bjrn
• Granted Patent: US 10,184,888 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 2021/7776 Index
• CPC Class Codes: G01N 21/412 Index profiling of optical fibres
• CPC Class Codes: G01N 21/4133 Refractometers, e.g. differential
• CPC Class Codes: G01N 21/552 Attenuated total reflection
• CPC Class Codes: G01N 21/554 detecting the surface plasmon resonance of nanostructured metals, e.g. localised surface plasmon resonance
• CPC Class Codes: G01N 21/77 by observing the effect on a chemical indicator
• CPC Class Codes: G01N 21/774 the reagent being on a grating or periodic structure
• CPC Class Codes: G01V 1/18 Receiving elements, e.g. seismometer, geophone or torque detectors, for localised single point measurements

Abstract

A device for determining a refractive index may be provided. The device including at least one waveguide having a core and a cladding surrounding the core, the cladding being at least partly removed in at least one first longitudinal portion and the core including at least one fiber Bragg grating in at least one second longitudinal portion. A method for determining a refractive index or a pressure change in a fluid may also provided. The method may include at least one waveguide having a core and a cladding surrounding the core, the cladding being at least partly removed in at least one longitudinal portion. A method for producing such a device may also be provided.

Claims

1. Device for determining a refractive index or hydrophone, which contains at least one waveguide (10) having a core (11) and a cladding (12) surrounding the core (11), the cladding (12) being at least partly removed in at least one first longitudinal portion (21) and the core containing in at least one second longitudinal portion (22) at least one fiber Bragg grating (4), at least one partial area of the surface (210) being provided in the first longitudinal portion (21) with nanoparticles (3), characterized in that the device further contains an apparatus for detecting the intensity of the light reflected by the fiber Bragg grating (4).

2. Device or hydrophone according to claim 1, characterized in that the second longitudinal portion (22) forms at least part of the first longitudinal portion (21).

3. Device or hydrophone according to claim 1, characterized in that periodic holes (220) are present in the cladding (12) adjacent to the fiber Bragg grating (4).

4. Device or hydrophone according claim 1, characterized in that the waveguide (10) is made as a single mode fiber.

5. Device or hydrophone according to claim 3, characterized in that the holes (220) contain clusters of nanoparticles (3).

6. Device or hydrophone according claim 1, characterized in that the nanoparticles (3) contain a metal or an alloy and have a plasmon frequency which corresponds approximately to a resonance frequency of the fiber Bragg grating (4).

7. Device or hydrophone according to claim 1, characterized in that the nanoparticles contain, or consist of, palladium.

8. Device or hydrophone according to claim 1, characterized in that at least one partial area of the surface provided with nanoparticles (3) in the first longitudinal portion additionally carries antibodies.

9. Device or hydrophone according to claim 1, further containing at least one laser light source, the emission wavelength of which corresponds approximately to the Bragg wavelength of the fiber Bragg grating (4), and at least one photodiode which is configured to receive light reflected by the fiber Bragg grating (4).

10. Device or hydrophone according to claim 1, characterized in that the first longitudinal portion (21) has a length of about 0.1 mm to about 5.0 mm or that the first longitudinal portion (21) has a length of about 0.5 mm to about 2.0 mm.

11. Device or hydrophone according to claim 1, further containing an apparatus for detecting the wavelength of the light reflected by the fiber Bragg grating (4).

15. Method for producing a device according to claim 1, characterized in that at least one fiber Bragg grating (4) in the core (11) of a waveguide (10) having a core (11) and a cladding (12) surrounding the core (11) is produced by point-to-point exposure with laser radiation and the cladding (12) of the waveguide (10) is then at least partly removed by wet or dry chemical etching and at least one partial area of the surface (210) of the core (11) is provided with nanoparticles (3).

12. Method for determining a refractive index or a pressure change of a fluid, which uses at least one waveguide (10) having a core (11) and a cladding (12) surrounding the core (11), the cladding (12) being at least partly removed in at least one first longitudinal portion (21) and the core in at least one second longitudinal portion (22) containing at least one fiber Bragg grating (4), characterized in that at least one partial area of the surface (210) in the first longitudinal portion (21) is provided with nanoparticles (3) and light is coupled into the core of the waveguide (11) and the refractive index and/or the pressure change is determined from the intensity of the reflected light.

13. Method according to claim 12, characterized in that antigens and/or viruses are also identified by additionally providing at least one partial area of the surface (210) of the core (11) in the first longitudinal portion (21) with antibodies.

14. Method according to claim 12, characterized in that laser light is coupled into the core (11) of the waveguide (10), the wavelength of which approximately corresponds to the Bragg wavelength of the fiber Bragg grating (4).

16. Method according to claim 14, characterized in that an aqueous solution of hydrogen fluoride is used for etching and periodic holes (220) are etched into the cladding (12) adjacent to the fiber Bragg grating (4).

17. Method according to claim 14, characterized in that the nanoparticles (3) are activated by a plasma.

18. Method according to claim 14, characterized in that the nanoparticles are deposited in the periodic holes (220) in clusters.

19. Method according to claim 14, characterized in that the wavelength of the light reflected by the fiber Bragg grating (4) is additionally determined.