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Proceedings Paper

Brillouin spectrum narrowing in high extinction ratio nanosecond pulse from phase locked DFB lasers
Author(s): Yun Li; Xiaoyi Bao; Jeffrey Snoddy; Liang Chen
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Paper Abstract

The Brillouin spectrum narrowing phenomenon for nanosecond pulses in Brillouin Optical Time Domain Analysis (BOTDA) sensor system is demonstrated with high extinction ratio (ER > 24 dB) nanosecond pulse over short fibre length (10 m). The line width of the Brillouin spectrum is ~52 MHz for 10 ns pulse by feedback phase locking of the pump and probe waves from: 1) DFB lasers (2 MHz bandwidth) and 2) fibre lasers (5 kHz bandwidth) at the Brillouin frequency. It is found that the coherent length (inverse of the Brillouin line width in the fibre) of the Brillouin scattering process is not determined by the laser bandwidth, rather by the enhanced phonon field generated from phase locked pump and probe lasers for nanosecond pulses. For the same bandwidth of the pump and probe lasers, the line width of the Brillouin spectrum with high extinction ratio nanosecond pulses under the phase locking of the pump and probe waves is much narrower than that from the frequency locking of the pump and probe waves at the Brillouin frequency.

Paper Details

Date Published: 5 August 2009
PDF: 8 pages
Proc. SPIE 7386, Photonics North 2009, 73861F (5 August 2009); doi: 10.1117/12.839204
Show Author Affiliations
Yun Li, Univ. of Ottawa (Canada)
Xiaoyi Bao, Univ. of Ottawa (Canada)
Jeffrey Snoddy, Univ. of Ottawa (Canada)
Liang Chen, Univ. of Ottawa (Canada)


Published in SPIE Proceedings Vol. 7386:
Photonics North 2009

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