INTEGRATED-OPTIC AMMONIA SENSOR

Fibre coupled optical sensors for chemical and biologial species are i mportant for process control, environmental control and pollution dete ction. An integrated optic ammonia sensor is described here; this is b ased on evanescent field absorption. The sensitive element of this sen sor is a strip waveguide, fabricated by field assisted ion exchange, c oated with a immobilized indicator dye. The sensor has a short respons e time and a long lifetime. An experimental arrangement is shown which has been built up for the characterization of different integrated op tic sensor elements. Spectral response characteristics, response times and the generation of reference signals are reported in detail. The s imple temperature dependence, the humidity independence and the very l ow cross sensitivity of this ammonia sensor is illustrated.