Dynamic Strain Measurement of 10-km Fiber With Frequency-Swept Pulsed BOTDA

Single-shot BOTDA based on an optical chirp chain probe wave for distributed ultrafast measurement

“…In a conventional BOTDA system, the distributed BGS is reconstructed by injecting a high-power pump pulse to interrogate the local-stimulated Brillouin scattering (SBS) and then sweeping the continuous probe wave frequency over a wide spectral range; such a process imposes the main limiting factor on the sampling rate 42 . To date, BOTDA for dynamic measurement is classified into three categories: frequency-comb-based sweep-free scheme 43 – 47 , slope-assisted scheme 30 , 31 , 39 , 42 , 48 , 49 , and fast-frequency sweeping scheme 50 , 51 . The sweep-free scheme makes use of a frequency comb to demodulate the BGS; however, there is a trade-off between the spatial resolution and the frequency interval for the comb, with the spatial resolution usually a few tens of meters.…”

“…Obviously, the sampling rate for this scheme depends on both the length of the FUT and the number of scanning frequencies. Recently, a frequency-sweep pulsed BOTDA 51 was implemented to obtain a Lorentzian-shaped correlated gain in the time domain by linear-frequency modulation of two 1.0-μs pulses as pump and probe pulses coupled with a point (20 m) dynamic strain measurement with a sampling rate of 10 kHz obtained at the end of 10 km. Although a distributed dynamic measurement can be realized through adjusting the delay between the probe and pump pulses, the effective sampling rate is divided by the sensing point number.…”

Multi-point dynamic strain sensing using external modulation-based Brillouin optical correlation domain analysis

“…In order to demonstrate the capability of phase modulation-based BOCDA in detecting dynamic strain variations at multiple locations, dynamic strain is emulated in Fiber 2 by switching the optical path [23] between two fibers whose Brillouin frequencies differ by 40 MHz approximately. The FUT is shown in Fig.…”

Recent progress in slope-assisted Brillouin optical correlation-domain reflectometry

“…To date, a variety of methods have been implemented to acquire the information on Brillouin gain spectrum (BGS) distributions, from which the magnitude and position of strain or temperature change can be derived [1]. One of the most widely used techniques is a time-domain technique, which includes Brillouin optical time-domain analysis (BOTDA) [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and Brillouin optical time-domain reflectometry (BOTDR) [18][19][20][21][22][23][24][25]. Their performance has been dramatically enhanced, and even sub-centimeter spatial resolution and real-time operation have been achieved.…”