Bend-insensitive ultra short long-period gratings by the electric arc method and their applications to harsh environment sensing and communication.

Ultra short long-period gratings (LPGs) fabricated using the electric arc discharge method are demonstrated with regular single-mode fibers. The gratings were as short as two periods, which were the shortest LPGs ever reported. The evolution of this short gratings and their characteristics are investigated in this paper. The excellent bending insensitivity and high temperature robustness demonstrated by this unique LPG make it particularly suitable for harsh environment sensing and communication.