Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating
- 2124 Promontory Cir., San Ramon, CA 94583
- 126 Echo Ave., Oakland, CA 94611
- 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
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