Recent advances in distributed optical fiber temperature sensing using the Landau-Placzek ratio

Distributed optical fiber temperature sensing (DTS) provides an elegant way of monitoring the temperature at many points without necessitating the accurate positioning of individual discrete sensors. This paper demonstrates recent advances in distributed temperature sensing based on spontaneous Brillouin scattering. A high spatial and temperature resolution is achieved by exploiting a novel low cost detection system. The experimental configuration consists of two key components; a Q-switched laser source to generate the backscattered signal and the low cost detection system which comprises an in-fiber double pass Mach-Zehnder interferometer and a sensitive InGaAs APD connected to a computer based averaging system. It is the relative low cost of these components which has made the Brillouin based temperature sensor so attractive for commercial exploitation. A spatial resolution of 3.0 meters with a Brillouin temperature resolution of 0.9 degrees C at a range of 16km has been achieved.