Detecting Submerged Objects by Brillouin Scattering (CAT#: STEM-ST-0158-YJL)

Name: Detecting Submerged Objects by Brillouin Scattering
SKU: STEM-ST-0158-YJL
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Introduction

The fundamental idea of detecting submerged objects, such as underwater rocks, fish, or the seabed, is to measure the intensity of the retro-reflected signal. If the intensity is strong enough, one can detect the existence of an object, and determine its depth under the water by the time delay of the signal. In the last two decades, light-scattering methods have been widely used in physical or chemical determinations and remote sensing of the ocean.

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Principle Applications Procedure Materials

Principle

From a quantum point of view, Brillouin scattering is an interaction of light photons with acoustic or vibrational quanta (phonons), with magnetic spin waves (magnons), or with other low frequency quasiparticles interacting with light. The interaction consists of an inelastic scattering process in which a phonon or magnon is either created (Stokes process) or annihilated (anti-Stokes process). The energy of the scattered light is slightly changed, that is decreased for a Stokes process and increased for an anti-Stokes process. This shift, known as the Brillouin shift, is equal to the energy of the interacting phonon and magnon and thus Brillouin scattering can be used to measure phonon and magnon energies.