NANO-OPTIC FILTER ARRAY BASED SENSOR

• US 20120129269A1
• Filed: 03/19/2010
• Published: 05/24/2012
• Est. Priority Date: 03/20/2009
• Status: Active Grant

• Current Assignee: NanoLambda, Inc.
• Original Assignee: NanoLambda, Inc.
• Inventors: Choi, Byung Il, Lee, Byounghee, Song, Min Kyu
• Granted Patent: US 9,395,473 B2
• Time in Patent Office: Days
• US Class Current: 436/164
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/0285 Nanoscale sensors
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 21/554 detecting the surface plasmon resonance of nanostructured metals, e.g. localised surface plasmon resonance
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: G02B 5/204 in which spectral selection is performed by means of a conductive grid or array, e.g. frequency selective surfaces for use with wavelengths longer than the infrared light H01Q15/0006

Abstract

A device such as a filter or reflector includes a conductive layer including a periodic pattern of elements. The elements have shapes and sizes configured such that a transmittance or reflectance spectrum of the conductive layer has a drop at a long-wavelength end. The elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength. The spectrum further includes a peal- between the dip and the drop.

Claims

1. A device comprising:

a conductive layer including a periodic pattern of elements;

wherein the elements have shapes and sizes configured such that a transmittance or reflectance spectrum of the conductive layer has a drop at a long-wavelength end of the spectrum;

wherein the elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength; and

wherein the spectrum further includes a peak between the dip and the drop.

2. The device of claim 1, wherein:

the elements include at least one of an aperture or a conductive particle, and wherein the aperture or the conductive particle has a characteristic size comparable to but smaller than a wavelength of interest;

the conductive layer comprises at least one of a highly conductive metal, an alloy of metals, a highly doped semiconductor, a carbon nanotube, a graphene, a material coated with highly conductive materials, or combined multiple layers thereof;

wherein a thickness of the conductor layer is thicker than an optical skin depth at a wavelength of interest;

wherein the elements include a plurality of apertures or gaps, and wherein the plurality of apertures or gaps have sharpened edges to concentrate electrical charges or fields to thereby enhance a transmittance or reflectance at the peak wavelength;

wherein the elements include a plurality of apertures or gaps, and wherein the plurality of apertures or gaps have narrowed widths to enhance sharpness of the dip and the peak;

wherein the elements have at least one of;

two alternating periods of the periodic pattern;

or

two alternating shapes or sizes, or

wherein the shapes of the plurality of apertures include at least one of a rectangle, a ninety-degree zigzag shaped slit, or a cross.

6. The device of claim 1, further comprising:

a magnetic material configured to affect a Plasmon mode of the conductive layer;

two dielectric layers, wherein the conductive layer is disposed between the two dielectric layers, wherein the elements include a plurality of apertures and gaps, and wherein the apertures and gaps are filled with a dielectric material the same as the two dielectric layers to thereby reduce numbers of dips and peaks in the spectrum and increase the transmittance or reflectance.

11. The device of claim 1, wherein the elements include apertures or gaps disposed over both sides of the conductive layer, and wherein shapes and sizes of the apertures or gaps over both sides of the conductive layer are the same.

12. The device of claim 1, wherein the elements include apertures or gaps disposed over both sides of the conductive layer, and wherein shapes and sizes of the apertures or gaps over both sides of the conductive layer are different.

13. The device of claim 1, further comprising another conductive layer, wherein:

a separation of two conductive layers is comparable to and smaller than a wavelength of interest;

the array elements include slits in the conductive layer, and wherein the slits each have a length larger than a width, and wherein the length is about half a pitch of the periodic pattern; and

the device is configured as a transmissive filter or a reflective filter.

16. The device of claim 1, wherein the conductive layer comprises:

a single highly conductive material across the device;

or at least two different highly conductive materials across the device.

17. The device of claim 1, further comprising at least two different dielectric materials sandwiching the conductive layer.

18. The device of claim 1, further comprising:

a dielectric layer adjacent the conductive layer, wherein at least one of the conductive layer or the dielectric layer is configured to receive a current or voltage input to modulate the transmittance or reflectance, and wherein the device is configured as a tunable optical filter or reflector;

another conductive layer, wherein a distance between the two conductive layers is smaller than a predetermined wavelength, and wherein the device is configured as a Fabry-Perot filter, the device further comprising a dielectric material between the two conductive layers, wherein the dielectric material comprises structures having a size comparable to the predetermined wavelength and configured to change an effective refractive index of the dielectric material; and

a plurality of filters and a plurality of photodetectors, wherein each of the plurality of filters comprises;

a conductive layer including a periodic pattern of elements;

wherein the elements have shapes and sizes configured such that the transmittance or reflectance spectrum of the conductive layer has a drop at a long-wavelength end of the spectrum;

wherein the elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength;

wherein the spectrum further includes a peak between the dip and the drop; and

wherein at least one of the plurality of filters and its associated photodetector or photodetectors are configured to perform at least one of the following;

monitoring an ambient light;

monitoring proximity;

or

color or spectral detection.

20. A method of designing the device of claim 1 to modify a spectral shape of an incident light, the method comprising:

simulating a transmittance or reflectance spectrum of a conductive layer, wherein the conductive layer has at least one periodic pattern of elements, wherein the elements include apertures in the conductive layer or conductive particles disposed over the conductive layer, and wherein the elements have a characteristic size comparable to a wavelength of the incident light;

configuring shapes and sizes of the elements such that the spectrum has a drop at a long wavelength end;

configuring a period of the elements such that the spectrum is suppressed at wavelengths resonant with at least one Plasmon resonant wavelength, wherein a peak is located between the dip and the drop; and

selecting an optimal configuration from a plurality of simulations having different configurations including at least one of;

the shapes, sizes or the period of the elements;

or

refractive indices of the conductive layer and adjacent layers.

3-5. -5. (canceled)

7-10. -10. (canceled)

14-15. -15. (canceled)

19. (canceled)

21. A system comprising:

an array of photodetectors;

an array of filters; and

a processing unit;

wherein each filter of the array of filters is optically coupled to a photodetector or a group of photodetectors of the array of photodetectors; and

wherein the processing unit is configured to calculate a vector value of outputs from the array of photodetectors and to perform at least one of;

analyzing properties of a target object;

monitoring a change of the target object;

or

estimating a spectral profile of light from a target object through at least one of the following methods;

linear, multi-linear, or nonlinear estimation,

trained mapping;

or

pattern recognition.

22. The system of claim 21, wherein the optical filters include at least one of:

a Fabry-Perot filter;

a linear variable filter;

a nanostructured thin film filter, or

a photonic crystal filter; and

wherein each of the filters comprises;

a conductive layer including a periodic pattern of elements;

wherein the elements have shapes and sizes configured such that a transmittance or reflectance spectrum includes a drop at a long-wavelength end;

wherein the elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength; and

wherein the spectrum further includes a peak between the dip and the drop; and

wherein;

the processing unit is configured to estimate a spectral profile of the light from the target object by sampling and digitizing a spectral response of the filters or combined spectral responses of each filter, and a spectral response of the photodetectors coupled to the filters, to thereby analyze properties of the target object;

wherein the vector value is one of;

an array of outputs from the photodetectors coupled to the filters;

a matrix of cross relationships among the outputs of the photodetectors;

a matrix of ratio relationships among the outputs of the photodetectors;

or

a matrix of first or second derivatives of the outputs of the photodetectors; and

wherein the linear or nonlinear estimation methods use at least one of the following operations;

matrix inversion;

equalization;

Moore-Penrose pseudoinverse;

least square;

linear or nonlinear regression;

or

neural network or multilayer neural network.

28. The system of claim 21, wherein the array of photodetectors is configured to use at least two different sizes of pixels or at least two different shutter times to enhance at least one of a sensitivity or a dynamic range, and wherein the processing unit is configured to normalize the outputs of the array of photodetectors through pixel binning;

and

wherein the array of photodetectors is configured to be partially covered by the array of filters such that the system is configured to obtain image data and spectral data at the same time; and

wherein the processing unit is configured to use a spatial, a temporal, or a moving time averaging process to improve a signal-to-noise ratio of the outputs from the photodetectors, wherein the spatial averaging process comprises repeating identical filters over the array of photodetectors and averaging the outputs, and wherein the temporal averaging process comprises reading the output from a photodetector repeatedly over multiple frames and averaging the outputs; and

wherein the processing unit is configured to use known input constraints to process the vector value to;

analyze properties of the target object;

monitor changes in the target object;

or

estimate a spectral profile of light from the target object;

wherein the known input constraint comprise at least one of;

positivity or negativity of the light from the target object;

known spectral data of light sources used;

boundary conditions of the light from the target;

or

temporal, spatial, or frequency modulated information.

32. The system of claim 21, further comprising memory configured to store a database of pre-tested or pre-measured relationship between the vector value and the properties of the target object, wherein the database is used to map or transform spectral response data into the properties of the target object;

and

wherein the processing unit is configured to convert or map the vector value into tristimulus values;

or

wherein the processing unit is configured to convert or map the vector value into International Commission on Illumination (CIE) XYZ values, xy chromaticity values, xyY values, or RGB values; and

wherein a mosaic pattern of groups of the filters is repeated spatially over the entire area of the array of photodetectors; and

wherein the number of filters in each group is at least four;

wherein spectral outputs of pixels within each group are used to define, process, or approximate a spectral response of said group and neighboring groups; and

wherein the system is configured as one of a transmissive flat panel display, a reflective flat panel display, a transreflective flat panel display, a photodetector array, an optical modulator, a multispectral imager, or a hyperspectral imager.

35. The system of claim 21, wherein the vector value of the outputs is converted or mapped into tristimulus values, the system further comprising:

a light source;

a light path; and

a wireless or wired communication device;

wherein the system is configured as a digital color or spectral measurement device;

or

wherein the color or spectral changing agent changes color or spectrum when the color or spectral changing agent comes into contact with a target biochemical material; and

wherein a degree of color or spectral change of the agent is related to an amount of the target biochemical being contacted; and

wherein the system is configured as one of;

an indirect biochemical material detection apparatus;

a color or spectral sensing device for TV;

a color or spectral sensing device for ambient light;

a color or spectral sensing device for a printer;

a color or spectral sensing device for a skin;

a color or spectral sensing device for food;

or

a color or spectral sensing device for process monitoring.

38. The system of claim 21, further comprising:

a light source;

a light path;

a mechanical device configured to attach the system to a body; and

a wireless or wired communication device;

wherein;

the system is configured as a noninvasive health monitoring device;

the light source is configured to emit light onto a part of body;

the array of photodetectors is configured to detect reflected, scattered, or transmitted light from the part of body; and

the vector value of the outputs from the array of photodetectors indicate the body'"'"'s vital or health information;

the mechanical device comprises at least one of a band, a clip, or a hook;

the light emitted from the light source outputs is modulated by at least one of frequency modulation, amplitude modulation, or code modulation;

the light from the light source is wavelength-multiplexed from light emitted by at least two light emitters;

the mechanical device is configured to attach the system to one of an earlobe, a finger tip, a wrist, or an upper arm of a person; and

further comprising a fluorescence material embedded in the part of body for enhancing the outputs from at least one of the array of photodetectors, or a reference light source and a reference light path for self calibration of the system; and

wherein the system is configured to self train or self calibrate a conversion between the vector value and the vital or health information at an initial use or after power off of the system.

23-27. -27. (canceled)

29-31. -31. (canceled)

33-34. -34. (canceled)

36-37. -37. (canceled)

39-46. -46. (canceled)

47. A filtering method, comprising:

providing incident radiation to a plasmonic filter; and

detecting a filtered reflected, scattered, or transmitted radiation from the filter which contains layer has a drop at a long-wavelength end of a spectrum, a dip at a Plasmon mode resonant wavelength, and a peak between the dip and the drop.

48. The method of claim 47 wherein a biochemical material is detected, comprising:

exposing a color or spectral changing agent to the biochemical material;

providing the incident radiation on the color or spectral changing agent;

sensing a color or spectral change using a color or spectral sensor by filtering the reflected, scattered, or transmitted light from the color or spectral changing agent; and

determining an amount of the biochemical material based on the color or spectral change.

49. A multi-purpose sensor comprising a plurality of filters and a plurality of photodetectors, wherein each of the plurality of filters comprises:

a conductive layer including a periodic pattern of elements;

wherein the elements have shapes and sizes configured such that a transmittance or reflectance spectrum of the conductive layer has a drop at a long-wavelength end of the spectrum;

wherein the elements have a period configured such that the spectrum has a dip at a Plasmon mode resonant wavelength;

wherein the spectrum further includes a peak between the dip and the drop; and

wherein at least one of the plurality of filters and its associated photodetector or photodetectors are configured to perform at least one of the following;

monitoring an ambient light;

monitoring proximity;

or color or spectral detection.

50. The multi-purpose sensor of claim 49, wherein the sensor is configured to be embedded in one of a portable device having a screen, a cellular phone, a TV or computer monitor.