A novel method to realize the adjustable phase-shifted fiber Bragg grating (FBG) is proposed in this paper.
By adjusting the air gap between two identical FBG, the phase shift has been changed, and the
transmission characteristics of such phase-shifted FBG can be tuned. Both theoretical simulation and
experimental measurement have been carried out to verify and demonstrate the idea. It has been shown
the proposed tuning method is effective and the experimental results agree well with the theoretical