A wavelength scanning BOTDR sensing system based on Rayleigh and Brillouin self-heterodyne detection

We propose a wavelength scanning Brillouin Optical Time Domain Reflectometer (WS-BOTDR) sensing system based on Rayleigh and Brillouin (RB) self-heterodyne detection for high-accuracy temperature measurement. This method scans the power spectrum by adjusting the wavelength of laser rather than the frequency, which possesses the benefits of both electric frequency difference scanning and optical frequency difference scanning. Furthermore, the adverse effects of laser wavelength instability, polarization fading and phase fluctuation can be effectively eliminated by employing RB self-heterodyne detection. The experimental results demonstrate that the proposed method can achieve a high-accuracy measurement of 0.8 degrees C in the 50 m heating section of 9.5 km optical fiber end. It is also found that, from a practical point of view, the proposed method has prospective applications where both high-accuracy measurement and long-distance sensing are the primary concerns.