Raman scattering is a phenomenon where the frequency of light changes due to the interaction between incident light and molecular motion when passing through a medium. It is also known as the Raman effect. In 1923, A.G.S. Smekal theoretically predicted the frequency change in scattering. In 1928, Indian physicist C.V. Raman observed the phenomenon of frequency shift in scattered light in gases and liquids. For his research in the field of light scattering and the discovery of the Raman effect, he was awarded the Nobel Prize in Physics in 1930. Raman scattering is a non-elastic scattering caused by the interaction between photons and various excitations of crystal molecules, such as vibrations and rotations. The incident light interacts with the optical phonons of the fiber itself, either absorbing or emitting phonons, resulting in scattered light with higher or lower frequencies.