Modeling and performance evaluation of ferrocene-based polymer clad tapered optical fiber gas sensors

The possibility of utilizing certain polymers, known as variable-index materials, as cladding in tapered optical fibers for gas sensing is explored. We have shown that any small variation in the refractive index of the cladding of a tapered single-mode fiber has a direct influence on the transmission characteristic of the tapered region. A 4% deviation in the refractive index of a certain polymer is obtained upon the exposure of the polymer to ammonia. Sensitivity, repeatability, and selectivity of several fabricated sensors are also illustrated. (C) 1998 Society of Photo-Optical Instrumentation Engineers.