Optical sensor and method

• US 10,168,471 B2
• Filed: 03/08/2013
• Issued: 01/01/2019
• Est. Priority Date: 03/08/2013
• Status: Active Grant

• Current Assignee: Predrag Mikulic, Saurabh Mani Tripathi, Wojtek J. Bock
• Original Assignee: Predrag Mikulic, Saurabh Mani Tripathi, Wojtek J. Bock
• Inventors: Bock, Wojtek J., Tripathi, Saurabh Mani, Mikulic, Predrag
• Primary Examiner(s): Smith, Chad H
• Application Number:
  US13/789,760
• Publication Number:
  US 20140254977A1
• Time in Patent Office: 2,125 Days
• Field of Search: None
• CPC Class Codes: G01D 5/35316 using a Bragg gratings
• CPC Class Codes: G01N 21/7743 the reagent-coated grating coupling light in or out of the waveguide
• CPC Class Codes: G02B 6/02085 characterised by the grating profile, e.g. chirped, apodised, tilted, helical

Abstract

An optical sensor has a waveguide having a core, a cladding having an outer surface and a long period fiber grating. The core, the cladding and the long period fiber grating collectively provide at least two resonant wavelengths. The optical sensor also has binding sites on the outer surface of the cladding for binding to elements to be detected to the outer surface of the cladding. The cladding may be thinned down to a thickness sufficiently low produce the resonant wavelengths. The binding sites include agents for binding to the elements to be detected with the agents being covalently bonded to the surface of the cladding. Example binding sites can include bacteriophages for detecting E. coli bacteria, Palladium for detecting hydrogen, or synthetic DNA for detecting viruses of certain molecules for example.

Claims

1. Use of an optical sensor capable of providing at least one split resonance in measuring spectral shifts in resonance wavelengths of the at least one split resonance to detect one or more elements in a water-based solution to be detected using said spectral shifts, the optical sensor comprising:

a waveguide having a circular core, a circular cladding having an outer surface and a long period fiber grating, the waveguide having a portion along its length including the circular core, the circular cladding and the long period fiber grating with the long period fiber grating having a single grating period within said portion of the waveguide, the circular core, the circular cladding and the long period fiber grating within said portion of the waveguide being tuned to collectively excite at least one cladding mode, each of the at least one cladding mode having a corresponding one of the at least one split resonance with two resonant wavelengths; and

binding sites on the outer surface of the circular cladding for binding to the elements to be detected to the outer surface of the circular cladding.

3. An optical sensor according to claim 1 wherein the cladding is thinned down to a thickness sufficiently low to produce the at least one split resonance.

4. An optical sensor according to claim 1 wherein the binding sites comprise a biophage.

5. An optical sensor according to claim 1 wherein the binding sites comprise a bacteriophage.

6. An optical sensor according to claim 1 wherein the binding sites comprise Palladium.

7. An optical sensor according to claim 1 wherein the binding sites comprise synthetic DNA.

8. An optical sensor according to claim 1 wherein the binding sites comprise at least two different types of binding sites capable of binding to different types of elements.

2. An optical sensor to detect one or more elements in a water-based solution comprising:

a waveguide having a core, a cladding having an outer surface and a long period fiber grating, the waveguide having a portion along its length including the core, the cladding and the long period fiber grating with the long period fiber grating having a single grating period within said portion of the waveguide, the core, the cladding and the long period fiber grating within said portion of the waveguide being tuned to collectively excite at least one cladding mode in the water-based solution, each of the at least one cladding mode having a corresponding one of at least one split resonance with two resonant wavelengths; and

binding sites covalently bonded on the outer surface of the cladding for binding to elements to be detected to the outer surface of the cladding.

9. A method of fabricating an optical sensor, to detect one or more elements in a water-based solution, having a waveguide with a circular core, a circular cladding having an outer surface and a grating, the waveguide having a portion along its length including the circular core, the circular cladding and the grating with the grating having a single grating period within said portion of the waveguide, the method comprising:

etching the circular cladding at the outer surface within said portion of the waveguide to thin the circular cladding down to a thickness sufficiently low to excite a cladding mode when the optical sensor is immersed in the water-based solution, the cladding mode having a split resonance with two resonant wavelengths.

10. A method according to claim 9 comprising:

covalently bonding binding sites to the outer surface of the circular cladding for allowing elements to be detected to bind to the outer surface of the circular cladding.

11. A method according to claim 9 wherein the grating is a long period fiber grating.

12. A system for detecting an element to be detected in a water-based solution, the system comprising:

an optical sensor comprising;

a waveguide having a circular core, a circular cladding having an outer surface and a long period fiber grating, the waveguide having a portion along its length including the circular core, the circular cladding and the long period fiber grating with the long period fiber grating having a single grating period within said portion of the waveguide, the circular core, the circular cladding and the long period fiber grating within said portion of the waveguide being tuned to collectively excite at least one cladding mode in the water-based solution, each of the at least one cladding mode having a corresponding one of at least one split resonance with two resonant wavelengths; and

binding sites on the outer surface of the circular cladding for binding to the element to be detected to the outer surface of the circular cladding;

a light source coupled to the optical sensor for providing light to the optional sensor; and

,

a detector coupled to the optical sensor for receiving said light after transmission through the optical sensor, measuring spectral shifts in the two resonance wavelengths of the at least one split resonance, and detecting the element to be detected using said spectral shifts.