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Measurement of Broadband Instantaneous Frequency by Stimulated Brillouin Scattering (CAT#: STEM-ST-0116-YJL)

Introduction

Characterization of an unknown microwave signal is important in high speed communications, radar detection, and space exploration fields, etc. Among them, the spectrum analysis and instantaneous frequency measurement (IFM) are widely used in radar warning receivers, anti-stealth defense, and electronic intelligence systems. Compared to the signal source analyzer, the IFM technique is able to determine the instantaneous frequency (i.e. spectrum changing with time) of an unknown signal with the use of low-cost and low-speed photodetectors instead of expensive electronic receivers.




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.

Applications

Brillouin scattering is used to determine acoustic velocities and elastic properties of a number of crystalline solids, glasses, and liquids.

Procedure

1. Sample preparation
2. Measurement by scattering detection instrument
3. Data analysis

Materials

Brillouin scattering measurement system (Brillouin spectrometer)