In-line optical fiber sensors based on cladded multimode tapered fibers.

The use of uniform-waist cladded multimode tapered optical fibers is demonstrated for evanescent wave spectroscopy and sensors. The tapering is a simple, low-loss process and consists of stretching the fiber while it is being heated with an oscillating flame torch. As examples, a refractive-index sensor and a hydrogen sensor are demonstrated by use of a conventional graded-index multimode optical fiber. Also, absorbance spectra are measured while the tapers are immersed in an absorbing liquid. It is found experimentally that the uniform waist is the part of the taper that contributes most to the sensor sensitivity. The taper waist diameter may also be used to adjust the sensor dynamic range.

[1]  B. Culshaw,et al.  Optical waveguide modelling and design for evanescent field chemical sensors , 1994 .

[2]  D Moodie,et al.  Fiber-optic refractometer that utilizes multimode waveguide overlay devices. , 1992, Optics letters.

[3]  N. Nath,et al.  Evanescent wave fiber optic fluorosensor: effect of tapering configuration on the signal acquisition , 1998 .

[4]  A. Mignani,et al.  Evanescent Wave Absorption Spectroscopy by Means of Bi-Tapered Multimode Optical Fibers , 1998 .

[5]  Kenneth O. Hill,et al.  Low-loss highly overcoupled fused couplers: Fabrication and sensitivity to external pressure , 1988 .

[6]  T Takeo,et al.  Silica glass fiber photorefractometer. , 1992, Applied optics.

[7]  Alex A. Kazemi,et al.  Highly sensitive hydrogen sensors using palladium coated fiber optics with exposed cores and evanescent field interactions , 1999 .

[8]  Reinhardt Willsch,et al.  A fibre Bragg grating refractometer , 2001 .

[9]  Sacharia Albin,et al.  Transmission property and evanescent wave absorption of cladded multimode fiber tapers. , 2003, Optics express.

[10]  Jose L. Cruz,et al.  In-line highly sensitive hydrogen sensor based on palladium-coated single-mode tapered fibers , 2003 .

[11]  David L. Kaplan,et al.  Tapered fiber tips for fiber optic biosensors , 1995 .

[12]  H. Ahlfeldt,et al.  Fiber optical Bragg grating refractometer , 1998 .

[13]  G. Laffont,et al.  Tilted short-period fibre-Bragg-grating-induced coupling to cladding modes for accurate refractometry , 2001 .

[14]  T. Birks,et al.  Shape of fiber tapers , 1992 .

[15]  Michael A. Butler,et al.  Micromirror optical-fiber hydrogen sensor , 1994 .

[16]  Joel Villatoro,et al.  Fabrication and modeling of uniform-waist single-mode tapered optical fiber sensors. , 2003, Applied optics.