Organic vapors detection using single mode fiber at third telecommunication window

An optical fiber sensor to detect Volatile Organic Compounds (VOCs) is presented in this work. A material that shows a color change (from orange to green) in presence of organic vapors, is fixed onto a cleaved ended pigtail by Electrostatic Self Assembly method [1]. This way, when an optical signal is guided to the device head, changes in the sensing material produce variations in the reflected optical power. Standard Mono mode fiber (9/125 μm) and a DBF laser (@ 1550nm) have been used. Typically, wider fibers (62.5/125 μm) and lower wavelengths (laying in the visible spectral) are used to measure the effect of color change, but working at 1550nm makes easier multiplexing several optical signals. A sensor was implemented and exposed to saturated concentrations of several VOCs, registering a change in the reflected optical power, especially significant for acetic acid.