In Stimulated Brillouin Scattering, there is an interaction between optical and acoustic wave. On what parameters does the frequency of this acoustic wave depends ?
For intense beams of light (e.g. laser) travelling in transparent medium may induce acoustic vibrations in the medium via electrostriction. The beam may display Brillouin scattering as a result of those vibrations, usually in the direction opposite the incoming beam. BS and SBS have satisfy to conservation laws of energy and momentum (phase matching). The mentioned conditions determine frequencies of light scattering and acoustical waves. The frequency spectra of acoustic vibrations is continuous from 0 to some GHz and determined by temperature and density of material (see Brillouin theory of thermal capacity). Amplification of acoustic vibration due to electrostriction takes place only for those vibrations that satisfy to phase matching.
Can a change in frequency of pump wave change the frequency of acoustic vibrations ?
No not at all. The power of stokes wave can never be equal to the input pump power.
Maximum conversion efficiency possible is the quantum limited efficiency which is the ratio, lamda_P/lamda_S (Obtained by using photon number conservation). Since lamda_P is always less than lamda_S, ratio will never become 1.
In Stimulated Brillouin Scattering, the acoustic wave frequency can be given by the equation: ω=4*π*n*ν*V/c, where ω is the acoustic wave frequency, n is the refractive index of the medium, ν is the incident laser frequency, V is the acoustic velocity in the medium, and c is velocity of light in the vacuum. So the paremeters that affect the acoustic wave frequency include: refractive index of the medium, incident laser frequency, and the acoustic velocity in the medium
What is the typical bandwidth of acoustic waves in chalcogenides ?
Do chalcogenide glasses have higher electrosctrictive coefficient than III-V semiconductors?
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Optics