A small modification of the fast and distributed slope-assisted Brillouin time domain analysis (SA-BOTDA) method allows it to easily implement pump-power independent measurements of strain and/or temperature, using the ratio between readings taken on both slopes of the Brillouin gain spectrum. Employing this new double SA-BOTDA measurement technique, fast (∼100 Hz at ∼1-kHz effective sampling rate) strain measurements are shown to be immune to pump pulse power variations as large as 6 dB. At the expense of halving the sampling rate, this technique still maintains all the benefits of its SA-BOTDA predecessor. In particular, its ability to handle (Brillouin) longitudinally inhomogeneous fibers is demonstrated.

We report a 10cm spatial resolution in a Brillouin-based distributed sensing system using two simultaneously launched gain and loss pump pulses, having slightly different durations. Post-recording subtraction of the probe signal, excited by the shorter pulse, from the corresponding one, obtained from the longer pump pulse, is no longer required, since it is done automatically by the overlapping parts of the gain and loss pump pulses. Using a 30ns gain pump pulse and a 29ns loss pump pulse we were able to improve upon previously published results, achieving a distributed strain measurement along a standard single mode optical fiber with a spatial resolution of ~10cm. This technique does not broaden the involved Brillouin gain spectra so that the strain/temperature sensitivity is not compromised.

No abstract

No abstract

No abstract