Optical element, refractive index sensor, refractive index sensor array, and biosensor

• US 8,269,956 B2
• Filed: 07/09/2009
• Issued: 09/18/2012
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Hashiguchi, Tsuyoshi, Hirai, Hideaki
• Primary Examiner(s): Toatley, Jr., Gregory J
• Assistant Examiner(s): Underwood, Jarreas C
• Application Number:
  US12/500,150
• Publication Number:
  US 20100014073A1
• Time in Patent Office: 1,167 Days
• Field of Search: None
• US Class Current: 356/128
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01N 21/41 Refractivity; Phase-affecting properties, e.g. optical path length G01N21/21 takes precedence
• CPC Class Codes: G01N 21/4133 Refractometers, e.g. differential
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G02B 5/008 Surface plasmon devices diffractive gratings with a pitch less than or comparable to the wavelength G02B5/1809; surface plasmons in integrated optics G02B6/1226; optical analysis of materials by means of surface plasmons G01N21/553
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength
• CPC Class Codes: G02B 5/203 having holographic or diffractive elements diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18

Abstract

An optical element for resonating and reflecting incident light having a wavelength includes a periodic structure formed of protrusions and recessions. A period of the periodic structure is equal to or less than the wavelength of the incident light. The incident light having the wavelength is resonated and reflected by a resonance caused between the incident light and the protrusions and recessions. Widths of the protrusions are spatially changed.

Claims

1. An optical element for resonating and reflecting incident light having a wavelength, comprising:

a periodic structure formed of protrusions and recessions, a period of the periodic structure being equal to or less than the wavelength of the incident light, and the incident light having the wavelength being resonated and reflected by a resonance caused between the incident light and the protrusions and recessions,

wherein widths of the protrusions are spatially changed.

2. The optical element as claimed in claim 1, wherein the widths of the protrusions are spatially changed while the period of the periodic structure is set constant.

3. The optical element as claimed in claim 1, wherein the widths of the protrusions are spatially changed while a refraction index of the periodic structure is set constant.

11. The optical element as claimed in claim 1, wherein the periodic structure includes a material that is transparent with respect to the incident light.

4. A refractive index sensor comprising:

an optical element for resonating and reflecting incident light having a wavelength, the optical element including a periodic structure formed of protrusions and recessions, a period of the periodic structure being equal to or less than the wavelength of the incident light, and the incident light having the wavelength being resonated and reflected by a resonance caused between the incident light and the protrusions and recessions, and widths of the protrusions being spatially changed;

a photodetector configured to detect a position on the optical element where the incident light is reflected,

wherein the position on the optical element changes in accordance with a refractive index of a sample provided on the optical element.

5. The refractive index sensor as claimed in claim 4, wherein the photodetector is formed of plural light receiving elements, and the light receiving elements are arranged in an array according to a change in the widths of the protrusions of the periodic structure of the optical element.

6. The refractive index sensor as claimed in claim 4, wherein the photodetector is formed of a linear CCD;

and the linear CCD is provided according to a change in the widths of the protrusions of the optical element.

7. The refractive index sensor as claimed in claim 4, wherein the photodetector is formed of a linear CMOS sensor;

and the linear CMOS sensor is provided according to a change in the widths of the protrusions of the optical element.

8. The refractive index sensor as claimed in claim 4, wherein the optical element and the photodetector are stacked on each other.

9. A refractive index sensor array comprising:

a refractive index sensor including

an optical element for resonating and reflecting incident light having a wavelength, the optical element including a periodic structure formed of protrusions and recessions, a period of the periodic structure being equal to or less than the wavelength of the incident light, the incident light having the wavelength being resonated and reflected by a resonance caused between the incident light and the protrusions and recessions, and widths of the protrusions being spatially changed, and

a photodetector configured to detect a position on the optical element where the incident light is reflected, the position on the optical element changing in accordance with a refractive index of a sample provided on the optical element,

wherein the refractive index sensor is arranged in a one-dimensional or two-dimensional array.

10. A biosensor comprising the refractive index sensor array as claimed in claim 9.