Optical component limitations to development of optical fibre sensors

Abstract

Interest in optical fibre sensors developed in earnest in 1977 and has grown since with increasing impetus, mainly because of their freedom from electromagnetic interference, their potential intrinsic safety and very high sensitivity in certain applications. Optical fibre sensors may be intrinsic, that is the fibre itself acts as the sensor, or extrinsic, in which the fibre is used only to convey light to and from an optical modulator; modulation may be by intensity, wavelength, phase, polarization, or by time. Considerable research effort has been mounted by industry and universities, and many laboratory examples of optical fibre sensors have been reported, but few have reached the market place. One reason for this is that many of the optical fibre components necessary for the sensors can be contrived in the laboratory but are not available in quantity at a commercial price which would justify industrial implementation of the sensors. Examples are remountable connectors with repeatable performance, directional couplers, cheap solid-state spectrometers, in-line dichroic gratings and filters, and other microcomponents. The paper gives examples of optical fibre sensors for which such optical components are necessary. It is hoped that this will stimulate physicists to undertake development of relevant optical components.