A twin-hole fiber was provided with Au-Sn alloy electrodes and thermally poled at 255 masculineC with 4.3 kV applied during 155 minutes. An electric field 6X107 V/m was recorded. The poled fiber was cleaved and etched, revealing that the depletion region overlapped the entire core, was wedge shaped and pointed towards the cathode. The recorded profile closely followed the spatial distribution of the poling field.

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Twin-hole fibers were provided with Au-Sn alloy electrodes and thermally poled at 255 degrees C. The evolution of the depletion layer was studied by etching fibers poled at varying poling temperatures. The electro-optic response was measured for different poling times. When the depletion region did not overlap the core the direction of the recorded field was opposite to the applied poling field. Poling for a longer time made the depletion region extend through the core and changed the sign of the recorded field.

We have recently introduced a new approach in the utilisation and actuation of liquid matrices inside microstructured optical fibers, by infiltrating in their capillaries magnetically active fluids, namely, ferrofluids. The specific optofluidic approach provides the possibility of actuation of the infiltrated liquid by applying an external magnetic field, thus, exhibiting magnetofluidic capabilities. We apply this infiltration protocol in microstructured optical fiber Bragg gratings for developing magnetic field tunable/sensitive photonic devices and sensing probes. The material and implementation considerations related to this infiltration approach of viscous and opaque ferrofluids inside microstructured optical fibers, and the corresponding effects on the guiding and scattering behavior of the microstructured optical fiber Bragg gratings are presented and discussed. An updated review on this infiltrated microstructured optical fiber devices will be presented, focusing on the demonstration of simple magnetofluidic configurations such as "on-off" Bragg grating trimmers, "infiber" magnetometers, ferrofluidic defected Bragg reflectors and external magnetic field modulators. The design principles of such "in-fiber" magnetofluidic photonic devices will be analysed, along with their particular functionalities and application prospects; while in addition, the infiltration and fiber capillary functionalisation processes will be presented.

The physics of electrically switched long-period grating in a twin-hole fiber with internal electrodes is studied. Dynamic measurements for the two polarizations show how the grating spectra shift in time due to the mechanical stress and heat transfer in the core and the cladding.