Optical sensing devices and methods

• US 7,903,906 B2
• Filed: 12/29/2006
• Issued: 03/08/2011
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Smith, Terry L., Koch, Barry J., Yi, Yasha
• Primary Examiner(s): WONG, TINA MEI SENG
• Application Number:
  US11/617,932
• Publication Number:
  US 20090310902A1
• Time in Patent Office: 1,530 Days
• Field of Search: None
• US Class Current: 385/12
• CPC Class Codes: G01N 21/7746 the waveguide coupled to a cavity resonator

Abstract

An optical sensing system and method of using it includes a light source and a first bus waveguide having an input port that is in optical communication with the light source. The system further includes a microresonator configured so that the light source excites at least first and second resonant guided optical modes of the microresonator. The microresonator includes a first location on a surface of a core of the microresonator where a field intensity of the first mode is greater than a field intensity of the second mode. The microresonator core has a first cladding at the first location. The microresonator also has a second location on a surface of the core of the microresonator where a field intensity of the first mode is less than or equal to a field intensity of the second mode, the microresonator core having a second cladding at the second location. The first cladding is different than the second cladding.

Claims

1. An optical sensing system comprising:

a light source;

one or more bus waveguides comprising a first bus waveguide, the first bus waveguide comprising an input port that is in optical communication with the light source; and

a microresonator configured so that the light source excites at least first and second resonant guided optical modes of the microresonator, the microresonator comprising;

a first location on a surface of a core of the microresonator where a field intensity of the first mode is greater than a field intensity of the second mode, the microresonator core having a first cladding at the first location;

a second location on a surface of the core of the microresonator where a field intensity of the first mode is less than or equal to a field intensity of the second mode, the microresonator core having a second cladding at the second location, the first cladding being different than the second cladding,

wherein one of the first and second cladding is an optically-thick cladding layer, wherein a perturbation introduced at the optically-thick cladding layer will be unlikely to interact with a first or second mode of the microresonator.

2. The optical sensing system of claim 1, wherein one of the first and second cladding is a functionalized layer that is capable of chemically specific bonding with an analyte.

3. The optical sensing system of claim 1, wherein the first and second cladding have different indices of refraction.

4. An optical sensing system comprising:

a light source;

one or more bus waveguides comprising a first bus waveguide, the first bus waveguide comprising an input port that is in optical communication with the light source; and

a microresonator comprising a surface, the microresonator optically coupled to the one or more bus waveguides, wherein the microresonator is configured so that the light source excites at least first and second resonant guided optical modes of the microresonator, the surface further comprising;

an unavailable first portion configured to not permit the first and second modes to interact with a perturbation of the microresonator at the unavailable first portion; and

an available second portion different from the one or more coupling regions and different from the unavailable first portion, wherein the available second portion is configured to permit the first and second modes to interact with the perturbation of the microresonator in a way that the first and second resonant guided optical modes interact differently with the perturbation,

wherein the microresonator surface comprises patterned cladding that prevents the perturbation from optical coupling to the unavailable first portion of the microresonator surface.

5. The system of claim 4 wherein the perturbation is one of a group consisting of:

a scattering center, and

a change in refractive index of the available portion of the surface of the microresonator;

the optical sensing system further comprising a detector in optical communication with the optical sensing system.

6. The system of claim 4 wherein the perturbation is a metallic, semiconductor, dielectric or metamaterial nanoparticle.

7. The system of claim 4 wherein the microresonator and the first bus waveguide are integrated on a substrate.

8. The system of claim 4, wherein the available portion comprises a functionalized layer that is capable of chemically specific bonding with an analyte.

9. The system of claim 4, wherein the unavailable portion comprises a cladding that has a different index of refraction than an available portion.

10. The system of claim 4, wherein microresonator is optically coupled to the one or more bus waveguides at one or more respective coupling regions of the microresonator surface, wherein the unavailable portion is distinct from the one or more coupling regions.

11. A method of detecting the presence of a perturbation of a microresonator comprising:

providing an optical sensing system comprising;

a light source;

one or more bus waveguides, the one or more bus waveguides comprising a first bus waveguide that has an input port that is in optical communication with the light source; and

a microresonator comprising a surface and being optically coupled to the one or more bus waveguides at one or more respective coupling regions of the surface, the microresonator being configured to support at least first and second resonant guided optical modes of the microresonator when the first and second modes are excited by the light source, the microresonator surface further comprising;

an unavailable first portion configured to not permit the first and second modes to interact with a perturbation of the microresonator at the unavailable first portion;

exciting the at least first and second resonant guided optical modes of the microresonator with the light source;

exposing an available second portion of the surface of the microresonator to a perturbation of the microresonator, wherein the available second portion is different from the unavailable first portion, the available second portion being configured to cause the perturbation to interact differently with the first and second resonant guided optical modes and

detecting the interaction,

wherein the microresonator surface comprises patterned cladding that prevents the perturbation from optical coupling to the unavailable first portion of the microresonator surface.

12. The method of claim 11 wherein the perturbation is one of a group consisting of:

a scattering center, and

a change in refractive index of the available portion of the surface of the microresonator.

13. The method of claim 11 wherein the perturbation is a metallic, semiconductor, dielectric or metamaterial nanoparticle.

14. The method of claim 11, wherein the step of exposing induces a first frequency shift in the first resonant guided optical mode and a second frequency shift in the second resonant guided optical mode, wherein the second frequency shift can be zero;

and

the step of detecting the interaction further comprises comparing the first frequency shift and the second frequency shift.

15. A method of detecting the presence of a perturbation of a microresonator comprising:

providing an optical sensing system comprising;

a light source;

one or more bus waveguides, the one or more bus waveguides comprising a first bus waveguide that has an input port that is in optical communication with the light source; and

a microresonator comprising a surface and being optically coupled to the one or more bus waveguides at one or more respective coupling regions of the surface, the microresonator being configured to support at least first and second resonant guided optical modes of the microresonator when the first and second modes are excited by the light source, the microresonator surface further comprising;

an unavailable first portion configured to not permit the first and second modes to interact with a perturbation of the microresonator at the unavailable first portion;

exciting the at least first and second resonant guided optical modes of the microresonator with the light source;

exposing an available second portion of the surface of the microresonator to a perturbation of the microresonator, wherein the available second portion is different from the unavailable first portion, the available second portion being configured to cause the perturbation to interact differently with the first and second resonant guided optical modes and detecting the interaction;

wherein the step of exposing induces a first frequency shift in the first resonant guided optical mode and a second frequency shift in the second resonant guided optical mode, wherein the second frequency shift can be zero; and

the step of detecting the interaction further comprises comparing the first frequency shift and the second frequency shift.