Title: Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

Abstract

A technique for increasing the excitation and collection of evanescent fluorescence radiation emanating from a fiber optic sensor having a high refractive index (n.sub.r), dielectric thin film coating has been disclosed and described. The invention comprises a clad optical fiber core whose cladding is removed on a distal end, the distal end coated with a thin, non-porous, titanium dioxide sol-gel coating. It has been shown that such a fiber will exhibit increased fluorescence coupling due in part by 1) increasing the intensity of the evanescent field at the fiber core surface by a constructive interference effect on the propagating light, and 2) increasing the depth of penetration of the field in the sample. The interference effect created by the thin film imposes a wavelength dependence on the collection of the fluorescence and also suggests a novel application of thin films for color filtering as well as increasing collected fluorescence in fiber sensors. Collected fluorescence radiation increased by up to 6-fold over that of a bare fused silica fiber having a numerical aperture (N.A.) of O.6.

Inventors:

Kao, Hung Pin ^[1]; Schoeniger, Joseph ^[2]; Yang, Nancy ^[3]

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+ Show Inventor Affiliations

1. 2124 Promontory Cir., San Ramon, CA 94583
2. 126 Echo Ave., Oakland, CA 94611
3. 72 Bacon Ct., Lafayette, CA 94549

Issue Date:

Mon Jan 01 00:00:00 EST 2001

Research Org.:

Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)

OSTI Identifier:

873556

Patent Number(s):

6188812

Assignee:

Kao, Hung Pin (2124 Promontory Cir., San Ramon, CA 94583);Schoeniger, Joseph (126 Echo Ave., Oakland, CA 94611);Yang, Nancy (72 Bacon Ct., Lafayette, CA 94549)

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G - PHYSICS G02 - OPTICS G02B - OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS

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G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G01N21/648 - {using evanescent coupling or surface plasmon coupling for the excitation of fluorescence}
G01N21/7703 - {using reagent-clad optical fibres or optical waveguides

G - PHYSICS G02 - OPTICS G02B - OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS

G02B6/262 - {Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements}
G02B6/4203 - {Optical features}

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DOE Contract Number:  

AC04-94AL85000

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

method; apparatus; enhanced; evanescent; fluorescence; color; filtering; refractive; index; film; coating; technique; increasing; excitation; collection; radiation; emanating; fiber; optic; sensor; dielectric; disclosed; described; comprises; clad; optical; core; cladding; removed; distal; coated; non-porous; titanium; dioxide; sol-gel; shown; exhibit; increased; coupling; due; intensity; field; surface; constructive; interference; effect; propagating; light; depth; penetration; sample; created; imposes; wavelength; dependence; suggests; novel; application; films; collected; sensors; 6-fold; bare; fused; silica; numerical; aperture; fused silica; sol-gel coating; numerical aperture; fiber optic; optical fiber; refractive index; titanium dioxide; film coating; radiation emanating; optic sensor; exhibit increased; clad optical; oxide sol-gel; fiber sensors; fluorescence radiation; interference effect; fiber sensor; evanescent fluorescence; color filter; /385/356/