“…For the temperature determination, the anti-Stokes Raman scattered light is regarded as the signal light, while the Stokes Raman scattered light is seen as the reference light. Thus the temperature ( T ) dependence of the intensity ratio F( T ) can be expressed as follows [ 21 ]: where and are the intensity of AS light and S light at temperature T , respectively, K AS and K S are coefficients concerning AS and S scattering cross-section, respectively, ν AS and ν S are the frequencies of AS light and S light, h is the Planck constant, ∆ ν is the Raman shift in the transmission medium, and k B is the Boltzmann constant, α AS and α S are the attenuation coefficients for the incident AS and S light, respectively, l is the location along the fiber.…”