Heterodyne detection technique using stimulated Brillouin scattering and a multimode laser.
We present, for the first time to our knowledge, the use of multiple axial laser modes in distributed temperature sensing based on stimulated Brillouin scattering. One axial mode stimulates a Stokes wave with a temperaturedependent Brillouin frequency shift in the 13-GHz range. Optical heterodyning of the stimulated Stokes wave with a second axial laser mode allows one to generate and evaluate a beat signal in a lower frequency range. Using diode-pumped solid-state lasers, we have reduced the Brillouin beat frequency to the 500-MHz range. Hence, low-cost detectors and conventional signal-processing techniques can be applied for the beat signal processing.
Czarske
J
J
Müller
H
H