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Publication Number
US-9864144-B2
Publication Date
2018-01-09
Expiration Date
Abstract
A multi-path interferometric sensor for sensing small changes in the refractive index of sensing arms thereof, such as caused by the presence of an analyte or changes in analyte concentration, is disclosed. The sensor includes a single light source, a single detector, and a plurality of interferometers or a single multi-path interferometer. The various sensing branches within the multi-path interferometric sensor each include a delay having a different length. This results in a different modulation frequency for each interferometer, each of carriers include phase information that correlates to a change in refractive index and, ultimately, analyte concentration. The plural carrier frequencies enable simultaneous detection of multiple samples.
Core Innovation
A multi-path interferometric sensor is described that uses a single light source for producing an optical signal, wherein the light source is configured for wavelength scanning through a range of wavelengths on a periodic basis. Surface waveguides define a plurality of interferometers, and each interferometer receives a portion of the optical signal in both a sensing branch and a reference branch. The sensing branch includes a sensing window in which a portion of a cladding of the waveguide defining the sensing branch is thinned relative to the cladding of the waveguide defining the reference branch.
Each sensing branch has a length that is different from one another, such that the portion of the optical signal received by each interferometer is characterized by a different modulation frequency as a consequence of the different length of the sensing branch. A detector receives the portion of the optical signal from each interferometer, and the architecture supports multiple interferometers with different path-length delays, producing distinguishable modulation-frequency characteristics for phase extraction.
The multi-path interferometric sensor is also described as enabling a multi-path interferometer having a plurality of sensing branches and a reference branch, where each sensing branch receives a portion of the optical signal. The sensing branches include sensing windows with thinned cladding relative to the reference branch, and the sensing branches and the reference branch have different lengths that produce different modulation frequencies. In this arrangement, a single detector receives the portion of the optical signal from each sensing branch and the reference branch.
Claims Coverage
Two independent claims are provided, each covering a multi-path interferometric sensor that distinguishes multiple sensing paths by different waveguide lengths that yield different modulation frequencies, while using a single wavelength-scanned light source and a single detector.
Single wavelength-scanned light source with multi-path interferometers
A multi-path interferometric sensor comprising a single light source for producing an optical signal, wherein the light source is configured for wavelength scanning through a range of wavelengths on a periodic basis; surface waveguides defining a plurality of interferometers; each interferometer includes a sensing branch and a reference branch, each receiving a portion of the optical signal; and a detector for receiving the portion of the optical signal from each interferometer.
Sensing windows with thinned sensing-branch cladding
Each sensing branch includes a sensing window in which a portion of a cladding of the waveguide defining the sensing branch is thinned relative to the cladding of the waveguide defining the reference branch.
Different sensing-branch lengths producing different modulation frequencies
Each sensing branch has a length that is different from one another; the portion of the optical signal received by each interferometer is characterized by a different modulation frequency as a consequence of the different length of the sensing branch of each interferometer.
Single detector receiving signals from multiple sensing and reference branches
A multi-path interferometric sensor comprising surface waveguides defining a multi-path interferometer, where the multi-path interferometer includes a plurality of sensing branches and a reference branch, each sensing branch and the reference branch receiving a portion of the optical signal; a single detector for receiving the portion of the optical signal from each sensing branch and the reference branch.
Sensing-branch and reference-branch length diversity for modulation-frequency separation
Each of the sensing branches has a length that is different from one another and different from the reference branch; the portion of the optical signal received by each sensing branch and the reference branch is characterized by a different modulation frequency as a consequence of the different lengths of each sensing branch and the reference branch.
Overall claim coverage centers on multi-path surface-waveguide interferometry using thinned-cladding sensing windows to define the sensing region and using different branch lengths to generate different modulation frequencies for multiple interferometric paths that are collectively received by a detector, including an arrangement using a single detector for signals from multiple sensing branches and a reference branch.
Stated Advantages
Enables simultaneous detection of multiple samples using a single detector output.
Some sensing structures can be identical (sensor 800).
Documented Applications
Multi-sample sensing using distinct interferometers/sensing branches configured for refractive-index sensing based on measurable phase shifts induced by analyte changes in the cladding.
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