A new method for the detection of xylene gas by using an optical waveguide (OWG) sensor was studied. The zinc oxide thin films was fabricated by the sensitive element of this glass optical waveguide sensor with coating thin film of zinc oxide on the surface of tin-diffused glass optical waveguide by dip coating. The optical waveguide sensor was used as a typical example to detect a kind of volatile organic compounds (VOCs) gas xylene. The results showed that the zinc oxide thin film has strong response to the xylene gas compared to other volatile organic compounds although they have same concentration. The sensor exhibits a linear response to xylene gas in the range of 1×10^－3 to 4×10^－6 (volume fraction) with rapid response and good reversibility and responsive time was less than 8 s. The sensor has the advantages of high sensitivity, good reversibility and easy fabrication.

Key words: glass optical-waveguide, zinc oxide thin film, xylene