Investigation Of The Key Technologies Of The Distributed Sensor Based On Brillouin Scattering

Brillouin distributed fiber senor is a novel technique, which uses the temperature and strain sensitivity of Brillouin scattering to detect in a long-distance fiber. Brillouin fiber ring laser can generate laser output, whose wavelength separates a Brillouin frequency shift from the pump wavelength. These two techniques attract more and more attention lately, and this paper investigates these two techniques from three aspects.Firstly, according to two different circumstances, which are long distance steady equations and short distance transient equations, two different numerical solutions are used to simulate the coupled wave equations. The parameters and the general principles in the simulation are discussed appropriately. Referring to these theories, Differential double-pulse pair (DDP) technique is proposed for ensuring large dynamic range and sub-meter spatial resolution, meantime it can improve the ability to detect small frequency shift, leading to achieve minimum detectable change lower than 1 MHz.Secondly, fiber ring cavity and the character of Brillouin fiber ring laser are simulated in theory. And a fiber laser system based on the Brillouin scattering is established in experiment. A 10 dBm stable Brillouin laser output is generated after optimizing the parameters and mastering the disciplines.Thirdly, based on Brillouin fiber ring laser and Brillouin distributed fiber senor, a novel system is proposed in order to remove the expensive frequency shifter and eliminate the demand for narrow bandwidth laser source. Thus, the whole system is relatively simple, and it can accomplish the distributed temperature and strain sensing in a long distance.