A fully packaged photonic integrated sensor for real-time detection of chemical contaminants in water solutions

In this paper, a real-time photonic integrated chemical sensor module is presented. The device, based on the evanescent field detection principle, consists of an interferometric structure integrated in a silicon chip, electrically controlled through a thermal phase modulator, and partially exposed to the liquid under test by means of a proper fluidic system. The sensor monitors the refractive index of the water solutions injected above the sensing area and detects a phase shift whenever a refractive index change, i.e. a change in the chemical composition of the solution, occurs. A fully packaged prototype has been developed and tested for the detection of inorganic contaminants in water samples. Results show the sensor capabilities in terms of high sensitivity, realtime functioning in the detection of toxic heavy metal quantitively.