INTEGRATED OPTICAL SENSORS FOR HALOGENATED AND NONHALOGENATED HYDROCARBONS

Optical devices with integrated Mach-Zehnder structures can be used for the detection of hydrocarbons, if one of the two arms of the interferometer is covered with a polymer sensitive to these gases. The protection of the reference arm with an inert material allows liquid phases to be examined as well. A combination of the sensitive layer on the chip with fiber optics, a light source, and a detection system enables a sensor to be set up. Furthermore, a device can be constructed that is able to apply multicomponent analysis using an array of different polymers that interact at the same time with an organic mixture. By iterative Runge-Kutta calculations or application of electrodynamic approaches, the structure of the chip and the measurement window (polymer length) on one of the arms can be optimized. Thus, calibration curves and the limit of detection can be given for a variety of hydrocarbons, even including perhalogenated compounds. Using the band of a light-emitting diode, spectral investigations become possible in a small range of 70 nm. The absolute interferometric phase can be determined using such spectral observations.