Fiberoptic sensors of many types are being developed. They can be categorized as amplitude-or phase-modulated devices. Various transduction processes have been employed including: microbend losses, evanescent coupling, polarization shifts, florescence, and elastic strains induced by changes in various physical parameters. The list of physical phenomena which have been detected is quite long including: acoustic, electric, and magnetic fields; angular and linear displacement, velocity, and acceleration; temperature, pressure, stress, strain; radiation dosage and trace gases; etc. A detailed presentation of fiberoptic sensors along with discussions of optical components etc. has been given in ref. 1. Examples of both an amplitude and an intensity modulated device are given below.