Range-scalable distributed acoustic sensing with EDFA repeaters demonstrated over 2227 km.

We demonstrate a new, to the best of our knowledge, range-scalable repeatered distributed acoustic sensing (DAS) solution sharing technology with existing long-haul subsea telecom networks capable of low noise and high spatial and temporal resolution. Single ended DAS interrogation through a 2227 km line comprising 39 repeatered fiber spans is demonstrated with a 10 m spatial resolution, a 1.78 kHz sampling rate, and a strain resolution of 35 pε/√Hz for the outermost span.

Synthesis of birefringent reflective gratings.

The layer-peeling method for reconstruction of fiber and waveguide gratings is extended to the case of birefringent reflective gratings with polarization-dependent background index and polarization-dependent effective index contrast. Using a discrete grating model, we characterize the set of possible reflection and transmission Jones matrices and show that for a given wavelength, the total structure can be represented by a discrete reflector sandwiched between two retardation sections. In reflection the discrete reflector acts as a partial polarizer.