INFLUENCE OF PUMP PULSE WIDTH ON THE PERFORMANCE OF BRILLOUIN OPTICAL FIBER SENSORS

In this article, we have investigated the influence of pump pulse width on the spatial resolution of optical fiber temperature and strain sensors based on stimulated Brillouin scattering. Pump pulse widths of 2, 5, 10, 20, 50, and 100 ns were used. For pulse widths of 2 and 5 ns, broadening of the Brillouin Gain Spectrum (BGS) is observed. That spectral broadening makes it difficult to estimate the center frequency of the BGS. Conversely, longer pulses (20, 50, or 100 ns) produce narrow spectra and high frequency accuracy, on one hand, and lead to a worse spatial resolution (2, 5, and 10 m), respectively on the other hand. A Pulse width of 10 ns showed an optimal balance between spatial and frequency resolutions. It enabled detection of temperature and/or strain variations of 156°C and 3630 µε over 100 m long sensing distance, with uncertainty of only 5.027×10⁻⁴ °C and 117×10⁻⁶ µε.