A Novel Method of Inducing Phase Shifts in Fiber Bragg Grating without Using Phase Mask

A method of inducing phase shifts in Fiber Bragg Grating (FBG) by increasing Dc refractive index of the FBG is presented and experimentally verified. Only submicrometer-precision in control is enough and the phase mask in not necessarily needed in fabrication. The proposed method is markedly advantageous in cost-effectiveness, flexibility and simplicity compared to traditional ways in fabrication and mass production particularly in applications like optical code-division multiple-access (OCDMA) en/decoder ,optical filter in which complex multi-phase shifts are needed.