Dept. of Geosciences Colloquium: Transmission fibre-optic sensing

Zoom: https://tau-ac-il.zoom.us/j/83294569872?pwd=WmdPUWRPdGVQejIvcXhsQmFJY094UT09

​Abstract:

Distributed Acoustic Sensing (DAS) is rapidly transitioning from an experimental technology to a mature element of the seismological toolbox. Despite numerous success stories in a wide range of applications, DAS continues to suffer from the limitation to short interrogation distances of typically few tens of kilometres and the high cost of the interrogation units. These drawbacks, often combined with plain curiosity, motivate the development of alternative fibre-optic sensing technologies.

In this talk, I will present two novel technologies based on the transmission, instead of back-scattering, of laser pulses, which enables interrogation distances of thousands of kilometres. While the first system exploits microwave-frequency signals, the second system co-uses the active noise cancellation in metrological frequency dissemination. For these kinds of transmission systems, we show that different segments of the fibre can have different sensitivities for deformation sensing, largely depending on fibre curvature. Data from a large-scale experiments support this theory and demonstrate that transmission-based systems can constrain earthquake source mechanisms using only a single time series.
 

Event Organizer: Dr. Roy Barkan