# US 8,542,957 B2 · Optical waveguide sensor and manufacturing method of the same

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- Number: US 8,542,957 B2
- Document ID: US8542957B2
- Status: Granted
- Kind: B2
- Application number: 13/086,455
- Filed: 2011-04-14
- Published: 2011-11-03
- Granted: 2013-09-24
- Earliest claimed: 2010-04-28
- Assignees: Denso Corporation
- Applicants: Shuichi Yamashita; Yukihiro Takeuchi
- Inventors: Shuichi Yamashita; Yukihiro Takeuchi
- Web page: https://patentgrep.com/patent/US8542957B2

## CPC

- G02B 6/125: Bends, branchings or intersections
- G01N 21/552: Attenuated total reflection
- G01N 2021/7783: {Transmission, loss}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

An optical waveguide sensor includes a substrate and an optical waveguide. The optical waveguide includes a core and a lateral clad. The core extends in a spiral shape above a surface of the substrate. The lateral clad is disposed in a same layer as the core above the surface of the substrate and is in contact with either side surfaces of the core. At least a part of a surface of the core located opposite from the substrate is a transmission surface from which light leaks and is absorbed by a detected object.

## Claims

### Claim 1

An optical waveguide sensor comprising:
a substrate; and
an optical waveguide including a core and a lateral clad, the core extending in a spiral shape above a surface of the substrate, the lateral clad disposed in a same layer as the core above the surface of the substrate and being in contact with either side surfaces of the core, at least a part of a surface of the core located opposite from the substrate being a transmission surface from which light leaks and is absorbed by a detected object, wherein
the substrate has a removed section that opens on the surface of the substrate,
portions of the core and the lateral clad bridging the removed section form a membrane, and
both the surface of the core located opposite from the substrate and a surface of the core facing the substrate are the transmission surfaces, and further comprising:
a support layer disposed on at least one of the transmission surfaces of the core for reinforcing the membrane, wherein
when the light guided in the optical waveguide has a wavelength λ, the support layer has a refractive index ns at the wavelength λ, and the support layer has a thickness ts, the support layer satisfies a relationship of ns×ts≦λ.

### Claim 2 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
when the core has a refractive index n1, the lateral clad has a refractive index n2, and a difference between the refractive index n1 and the refractive index n2 is indicated by Δn, the optical waveguide satisfies a relationship of:
0.02n12−0.17n1+0.36≦Δn≦0.51n12−3.10n1+4.95.

### Claim 3 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
the core has a thickness of equal to or less than 2.0 μm.

### Claim 4 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
the refractive index n1 of the core is less than or equal to 3.

### Claim 5 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
the lateral clad has a refractive-index inclination portion in a predetermined region from a boundary with the core, and a refractive index of the refractive-index inclination portion decreases continuously or in a stepwise manner with a distance from the core.

### Claim 6 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
the removed section is a through hole that penetrates the substrate from the surface to an opposite surface.

### Claim 7 (depends on 1)

The optical waveguide sensor according to claim 1, wherein
the support layer satisfies a relationship of ns×ts≦0.3λ.

### Claim 8 (depends on 1)

The optical waveguide sensor according to claim 1, further comprising
a light source that inputs the light to an input end of the optical waveguide, and
a light detector that detects the light output from an output end of the optical waveguide.