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I am researching smart structures using optical fibre based sensors. One type used is distributed sensors of which there are two main kinds: ROTDR (Raman Optical time domain reflectometer) and BOTDR (Brillouin Optical time domain reflectometer). The former is based on Raman scattering within the fiber, and the latter is based on Brillouin scattering within the fiber.
Both types of scattering are inelastic, producing scattered light of a different wavelength to the incident light, as opposed to Rayleigh scattering which is eleastic.
From what I understand Raman scattered light is scattered at different (much higher THzs) frequency than Brillouin scattered light (GHzs), and the main difference between the two types is simply the way they are measured...Raman scattering schemes measure an intensity change in the back scattered light, while Brillouin scattering schemes measure a frequency shift in the back scattered light.
If they scatter within different frequency bands, and are measured in such different ways, there must be an explanation of how the two different mechanisms are different at an atomic/molecular scale...however I cannot find a reason why.
Both types of scattering are inelastic, producing scattered light of a different wavelength to the incident light, as opposed to Rayleigh scattering which is eleastic.
From what I understand Raman scattered light is scattered at different (much higher THzs) frequency than Brillouin scattered light (GHzs), and the main difference between the two types is simply the way they are measured...Raman scattering schemes measure an intensity change in the back scattered light, while Brillouin scattering schemes measure a frequency shift in the back scattered light.
If they scatter within different frequency bands, and are measured in such different ways, there must be an explanation of how the two different mechanisms are different at an atomic/molecular scale...however I cannot find a reason why.