Abstract: A method of providing in-line Raman amplification in an optical fiber sensing system, including the procedures of generating a probe light having a probe wavelength, transmitting the probe light into an optical fiber, generating at least one Raman pump light at a respective pump wavelength, the pump wavelength being shorter than the probe wavelength, generating at least one Raman seed light at a respective seed wavelength, the seed wavelength being between the pump and probe wavelengths, transmitting the Raman pump light into the optical fiber, transmitting the Raman seed light into the optical fiber and propagating the Raman pump light, the Raman seed light and the probe light along the optical fiber to achieve distributed Raman amplification of signal light produced by the probe light as it propagates along the optical fiber.

Abstract: Distributed fiber sensing system including a laser source, a circulator, a detector and an optical fiber, the circulator coupled with the laser source, the detector and the optical fiber, the laser source for generating at least two ultra-narrow linewidth interrogating pulses, the detector having a predetermined detection bandwidth for detecting back-scattered signals, the laser source including an ultra-narrow linewidth laser and a modulator, coupled with the ultra-narrow linewidth laser and the circulator, the modulator generating a plurality of pairs of interrogating pulses having a time delay, a frequency difference between two pulses of the same interrogating pair being less than the predetermined detection bandwidth and a frequency difference between two pulses not of the same interrogating pair being larger than the predetermined detection bandwidth, wherein the optical fiber can be characterized based on beat-notes between back-scattered signals originating from the pair of interrogating pulses detect

Abstract: A method of providing in-line Raman amplification in an optical fiber sensing system, including the procedures of generating a probe light having a probe wavelength, transmitting the probe light into an optical fiber, generating at least one Raman pump light at a respective pump wavelength, the pump wavelength being shorter than the probe wavelength, generating at least one Raman seed light at a respective seed wavelength, the seed wavelength being between the pump and probe wavelengths, transmitting the Raman pump light into the optical fiber, transmitting the Raman seed light into the optical fiber and propagating the Raman pump light, the Raman seed light and the probe light along the optical fiber to achieve distributed Raman amplification of signal light produced by the probe light as it propagates along the optical fiber.