An analysis is presented for etched optical fiber Bragg reflectors using the normal mode based orthogonal coupled mode theory for the grating assisted coupling of forward and backward modes and, using waveguide mode based non orthogonal coupled mode theory for the mode excitation at the input/output junction. The analysis shows that three are three kinds of Bragg reflections in the reflector, which means six distinct peaks in the reflective spectrum when its polarization sensitivity taken into account. It agrees well with the experimental result. The power reflectivity depends on not only coupling coefficients but also structure parameters, especially the depth of the Al 2O 3 layer, the distance between the Al 2O 3 layer and the fiber core, and the refractive index of the index matching layer.