Influence of uniaxial crystal material cladding on reflectivity and dispersion of uniform fiber Bragg grating

Abstract

The fiber Bragg grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of fiber Bragg grating proposed in the paper published in 2003 was investigated again and an error was corrected in the calculation, its effective index, reflectivity and dispersion were examined using coupled-mode theory and numeric solution. The calculated results indicate that no low frequency cutoff phenomenon exists in the HE11 mode, more power is transmitted by the core of the fiber with cladding made of isotropic material, the reflectivity of the fiber Bragg grating with cladding made of uniaxial crystal material is much higher than that with cladding made of isotropic material, the parameter Kcl, i.e., the ratio of the extraordinary to the ordinary ray refractive index, has a stronger impact on the reflectivity, Bragg wavelength and the dispersion of this kind of fiber Bragg grating when it varied from 1.00 to 1.01 than in other regions. This means that the characteristics of the fiber Bragg grating with uniaxial crystal cladding can be changed through adjusting Kcl while keeping its length, periodicity and the other parameters as constants.