Horizontally-scalable microcavity-enhanced raman scattering integrated platform for multigas chemical analysis

Patent metadata

Field	Value
Publication number	US-10401296-B1
Application number	US-201615065438-A
Country	US
Kind code	B1
Filing date	Mar 9, 2016
Priority date	Apr 13, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

An integrated approach to optical sensing (˜cm3 excluding electronics) at concentrations of parts-per-million or less (ppm). The invention enables the trace detection of chemicals in fluids (gas or liquid) in a highly integrated package. The simultaneous detection of any number of Raman active molecular species (including isotopes) may be achieved in a scalable, low-cost manner.

First claim

What is claimed is:

1. A horizontally-scaled Raman sensor for chemical analysis of a fluid, where the concentration of multiple chemical species of interest in a sample can be detected simultaneously, said sensor comprising:
a first high-reflector micromirror having a substantially planar surface;
an array of second high-reflector micromirrors each having a curved concave surface,
wherein a longitudinal extent of said substantially planar surface is substantially parallel to a longitudinal extent of said curved surface,
a channel formed between said first high-reflector micromirror and said array of second high-reflector micromirrors, said sample following a path of travel through said channel and along said substantially planar and curved surfaces;
an array of ultrahigh finesse microcavities formed between said substantially planar surface and each concave micromirror, said array of microcavities each having a microcavity length equal to the distance between said substantially planar surface of said first high-reflector micromirror and said curved surface of said each second high-reflector micromirror;
an excitation laser positioned to emit a light beam incident upon said first high-reflector micromirror and said each second high-reflector micromirror;
a Raman emission signal detector positioned to receive an array of Raman shifted emission signals in order to detect a concentration of a species of interest within said sample that is disposed between said substantially planar surface of said first high-reflector micromirror and said curved surface of said array of second high-reflector micromirrors, wherein said microcavities enhance a magnitude of said Raman shifted emission signals,
said first high-reflector micromirror and said each second high-reflector micromirror each exhibiting a high reflectivity of greater than about 99.9% both at a frequency of said light beam emitted by said excitation laser and at a frequency of a Raman-shifted signal of said species of interest,
whereby at least one of said array of second high-reflector micromirrors is resonant with a frequency of said excitation laser frequency and doubly-resonant with said Raman-shifted signal of said species of interest,
whereby said species of interest can be detected at concentrations of parts-per-million or less.

2. A sensor as in claim 1 , wherein said first high-reflector micromirror is a semiconductor mirror.

3. A sensor as in claim 2 , wherein said first high-reflector micromirror and said each second high-reflector micromirror are dielectrically coated.

4. A sensor as in claim 2 , further comprising gain layers, including quantum wells or quantum dots, are present within said semiconductor micromirror.

5. A sensor as in claim 1 , further comprising a laser focusing component positioned between said excitation laser and said first high-reflector micromirror to focus or mode match said light through said microcavities.

6. A sensor as in claim 5 , wherein said laser focusing component is a microlens array having a curvature that matches said first and second micromirrors to said microlens array.

7. A sensor as in claim 1 , further comprising a secondary filter that removes any residual laser pump light, said secondary filter positioned between said Raman emission signal detector and said first and second micromirrors.

8. A sensor as in claim 1 , wherein said microcavity length is tunable piezoelectrically.

9. A sensor as in claim 1 , wherein said sample is selected from the group consisting of a gas and a liquid.

10. A sensor as in claim 1 , wherein said microcavity length is about 1 μm to about 10 μm.

11. A sensor as in claim 1 , wherein said excitation laser is an array of vertical-external-cavity surface-emitting lasers.

12. A sensor as in claim 1 , wherein said excitation laser is a non-resonant laser.

13. A sensor as in claim 1 , wherein said array of second high-reflector microcavities includes about 10,000-1,000,000 microcavities on a 1 cm 2 area.

14. A sensor as in claim 1 , wherein said Raman emission signal detector includes image processing that yields a signal with magnitude that scales with the number of microcavities in said array of microcavities.

15. A sensor as in claim 1 , wherein said array of second high-reflector micromirrors are disposed directly adjacent to one another, such that said array of microcavities are adjacent to one another also.

16. A sensor as in claim 1 , wherein a radius of curvature of said curved concave surface of said each second high-reflector micromirror is smaller than a distance between adjacent curved concaved surfaces.

17. A sensor as in claim 1 , wherein said Raman emission signal detector is a charge-coupled device.

18. A horizontally-scaled Raman sensor for chemical analysis of a fluid, where the concentration of multiple chemical species of interest in a gas or liquid sample can be detected simultaneously, said sensor comprising:
a first high-reflector semiconductor micromirror having a substantially planar surface;
an array of second high-reflector micromirrors each having a curved concave surface, wherein said first high-reflector micromirror and said each second high-reflector micromirror are dielectrically coated,
wherein a longitudinal extent of said substantially planar surface is substantially parallel to a longitudinal extent of said curved surface,
wherein said array of second high-reflector microcavities includes about 10,000-1,000,000 microcavities on an approximately 1 cm 2 area,
wherein a radius of curvature of said curved concave surface of said each second high-reflector micromirror is smaller than a distance between adjacent curved concaved surfaces;
a channel formed between said first high-reflector micromirror and said array of second high-reflector micromirrors, said sample following a path of travel through said channel and along said substantially planar and curved surfaces;
an array of ultrahigh finesse microcavities formed between said substantially planar surface and each concave micromirror, said array of microcavities each having a microcavity length equal to the distance between said substantially planar surface of said first high-reflector micromirror and said curved surface of said each second high-reflector micromirror,
wherein said microcavity length is tunable piezoelectrically, wherein said microcavity length is about 1 μm to about 10 μm,
wherein said array of second high-reflector micromirrors are disposed directly adjacent to one another, such that said array of microcavities are adjacent to one another also,
an excitation laser positioned to emit a light beam incident upon said first high-reflector micromirror and said each second high-reflector micromirror, wherein said excitation laser is a non-resonant laser or an array of vertical-external-cavity surface-emitting lasers;
a laser focusing component positioned between said excitation laser and said first high-reflector micromirror to focus or mode match said light through said microcavities, wherein said laser focusing component is a microlens array having a curvature that matches said first and second micromirrors to said microlens array;
a charge-coupled device positioned to receive an array of Raman shifted emission signals in order to detect a concentration of a species of interest within said sample that is disposed between said substantially planar surface of said first high-reflector micromirror and said curved surface of said array of second high-reflector micromirrors, wherein said microcavities enhance a magnitude of sa

Assignees

• Muller Andreas
• Univ South Florida

Inventors

• Muller Andreas

Classifications

• G01N2021/651

  Cuvettes therefore · CPC title

• G01N21/65 Primary

  Raman scattering · CPC title

• A61B2562/046

  in a matrix array · CPC title

• A61B2562/0233

  Special features of optical sensors or probes classified in A61B5/00 · CPC title

• A61B2562/028

  Microscale sensors, e.g. electromechanical sensors [MEMS] · CPC title