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

Patent · Mon Jan 01 00:00:00 EST 2001

OSTI ID:873556

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

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

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.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-94AL85000
• 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 Number(s): US 6188812
• OSTI ID: 873556
• Country of Publication: United States
• Language: English

Related Subjects

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
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