This paper estimates the nonlinear refractive index of low attenuation bend insensitive fiber through experiments and simulation. We have studied and analysed the impact of all optical parameters such as wavelength difference of dual-frequency input signal, fiber length, effective area and dispersion on nonlinearity measurements of this fiber. In addition, a comparative study has been made between different fiber types with different optical properties to choose the more tolerant fiber against nonlinearity for high power fiber optic communications.