Effect of infiltration pressure on the birefringent properties of a side-hole fiber filled with indium.

The effect of the infiltration pressure on the birefringent properties of a side-hole fiber filled with indium was investigated by the fiber-optic Sagnac loop interferometry. The fiber was made at the various gas pressures during the metal infiltration process. It was found that the birefringence of the fiber strongly decreased from 5.55×10(-4) to 1.68×10(-4) with the increase of the pressure from 15 to 45 bars, due to the compensation effect of the pressure applied during the infiltration. The temperature dependence of the birefringence, dB(m)/dT, was found to be constant of ∼-3.06×10(-6)/K regardless of the magnitude of the pressure.