A Preliminary Detection On Organic Gas By Planar Optical Waveguide

With the rapid development of sensor technology, sensor application has become a main means to detect the small changes of our surrounding environment. In the field of sensor, planar optical waveguide sensor based on integrated optics has become an important research branch. For optical waveguide gas sensor, most studies focus on the response of the physical quantity to light intensity, this research focus on sensor technology of a five-layer planar optical waveguide, which includes the production of low concentration gas in the laboratory, and the detecting the gas by the optical waveguide. Results will lay the basis for the development of the gas sensor in the future.First of all, we design and optimize the structure of planar optical waveguide by softwares, and use PECVD (Plasma Enhanced Chemical Vapor Deposition) technique to fabricate the non-symmetric five-layer planar optical waveguide. Then, we use the linear CCD (Coupled Devices Charge) to collect the interference fringes generated by a laser through the optical waveguide. Finally, choose ethanol, isoamyl acetate, and xylene to prepare low concentration organic gases in the laboratory. Because different concentrations of gases will change the effective refractive index of upper and lower layer of the waveguide, as a result, the optical interference fringes move. To compare the relationship between fringe movement and gas concentration, we confirm the response of optical waveguide to gas concentration, which will lay a foundation for the follow-up research of planar optical waveguide sensor.