We present a novel distributed Brillouin optical time domain reflectometer (BOTDR) using standard telecommunication fibers based on single-photon avalanche diodes (SPADs) in gated mode, ν−BOTDR, with a range of 120 km and 10 m spatial resolution. We experimentally demonstrate the ability to perform a distributed temperature measurement, by detecting a hot spot at 100 km. Instead of using a frequency scan like conventional BOTDR, we use a frequency discriminator based on the slope of a fiber Bragg grating (FBG) to convert the count rate of the SPAD into a frequency shift. A procedure to take into account the FBG drift during the acquisition and perform sensitive and reliable distributed measurements is described. We also present the possibility to differentiate strain and temperature.

We investigate a novel distributed Brillouin optical time domain reflectometer (BOTDR) using standard telecommunication fibers based on single-photon avalanche diodes (SPADs) in gated mode, ν −BOTDR, with a range of 120 km and 10 m spatial resolution. We experimentally demonstrate the ability to perform a distributed temperature measurement, by detecting a hot spot at 100 km. Instead of using a frequency scan like conventional BOTDR, we use a frequency discriminator based on the slope of a fiber Bragg grating (FBG) to convert the count rate of the SPAD into a frequency shift. A procedure to take into account the FBG drift during the acquisition and perform sensitive and reliable distributed measurements is described. We also present the possibility to differentiate strain and temperature.

Angular momentum is an important physical property that plays a key role in light-matter interactions, such as spin-orbit interaction. Here, we investigate theoretically and experimentally the spin-orbit interaction between a circularly polarized optical (spin) and a transverse vortex acoustic wave (orbital) using Brillouin backscattering in a silica optical nanofiber. We specifically explore the state of polarization of Brillouin backscattering induced by the TR21 torso-radial vortex acoustic mode that carries an orbital angular momentum. Using a full-vectorial theoretical model, we predict and observe two operating regimes for which the backscattered Brillouin signal is either depolarized or circularly polarized, depending on the input pump polarization. We demonstrate that when the pump is circularly polarized and thus carries a spin angular momentum, the backscattered signal undergoes a handedness reversal of circular polarization due to opto-acoustic spin-orbit interaction and the conservation of overall angular momentum.

We present a long-range Brillouin optical time domain reflectometer (BOTDR) based on photon counting technology using single-mode fibres. We use the slope of a fiber Bragg grating (FBG) as a frequency discriminator, in order to convert count rate variation into a frequency shift. We demonstrate experimentally the ability to perform a distributed temperature measurement, by detecting a hot spot in a thermal bath and the possibility to achieve measurement above 100 km with a spatial resolution of 10 m. A performance study of our distributed sensor as a function of the photon counter efficiency is also presented.

We demonstrate the potential of Brillouin distributed fiber sensor for the measurement of groundwater flow in an experimental site of Port Douvot close to the city of Besan¸con. The flow measurement is obtained by using active heating method based on heat pulse instrument. An industrial sensor cable with single mode fiber and multimode fiber was immersed on ground. We compare distributed Brillouin sensor reflectometry (BOTDR) and Analysis (BOTDA) on single mode fiber (SMF) and multimode optical fiber (MMF) with a spatial resolution of 1 m, a temperature resolution of 0.2 °C and an acquisition time of 1 min. These parameters are compatible with hydrology application. Active heating of borehole water in conjunction with fiber optic distributed temperature sensor measurements are realized. Contrary to Raman based distributed temperature sensor, Brillouin instrument allows measuring absolute temperature measurement and simplify the implementation on the setup. We demonstrate in this paper that Brillouin scattering based temperature sensor can be used for hydrogeology application.

After presenting a theoretical modelling based on the heat equation, we show two different experiments to measure the laser induced temperature variation in silica nanofibers in air, a direct one and an indirect one based on Brillouin scattering, leading to an estimated value of the convective parameter h.

We present experimental results demonstrating the possibility to tune the wavelength of the photon pair emitted through four wave mixing in a nanofiber, using the pressure of a gas surrounding the nanofiber. Using Argon, a shift of idler wavelength of -1.1nm/bar is measured demonstrating fine adjustment possibility of emission wavelength, allowing to choose between different WDM channels.