Theoretical evaluation of Brillouin dynamic grating length localized by optical correlation domain technique through reflection spectrum simulation

Abstract

We derive formulae based on Fourier transformation to calculate the reflection spectrum of a Brillouin dynamic grating (BDG), which is localized along an optical fiber by an optical correlation domain technique. First, we calculate the typical reflection spectra of the BDG localized by the technique and confirm the validity of the formulae by showing coincidence with previous theoretical or experimental works. Next, we evaluate theoretically the spatial resolution in the BDG distributed measurement by the technique, through simulations considering different strained fiber lengths. It is confirmed theoretically, for the first time, that the resolution in the BDG measurement is worse than that for the Brillouin gain spectrum.

Brillouin Optical Correlation-Domain Technologies Based on Synthesis of Optical Coherence Function as Fiber Optic Nerve Systems for Structural Health Monitoring

“…To clarify the degradation of the spatial resolution, a simulation technique for the BDG-distributed measurement based on the BOCDA technique has been developed. Figure 44 shows the simulation results [108]. In the upper portion of Figure 44, the fiber sample that was used in the simulations is shown.…”

“…From the simulations and experiments, it is known that the equivalent spatial resolution for the BDG distributed measurement by the BOCDA is worth more than that of the BFS measurement [108]. The reason for the degradation of the spatial resolution was thought to be attributed to the side lobes existing on both the sides of the correlation peak position.…”

“…(a) Fiber considered in the simulations; strained section is set at the correlation peak position whose length is changed in the simulations. (b) BDG reflection spectra simulated for the cases with different lengths of the strained section; (b-1), (b-2), and (b-3) correspond to the strained section lengths of 5d z , 15d z , and 25d z , respectively, where d z is the theoretical spatial resolution for BOCDA [108]. Figure 44.…”

Simultaneous temperature sensing using distributed cascading fiber Bragg grating-based single-ended Brillouin optical time-domain analyzer

“…Brillouin scattering-based optical fiber sensors have four main structures, depending on their different functions. These are: Brillouin optical time-domain analyzers (BOTDAs) [8][9][10][11]; Brillouin optical time-domain reflectors (BOTDRs) [12,13]; Brillouin optical frequency-domain analyzers (BOFDAs) [14,15] and Brillouin optical correlationdomain analyzers (BOCDAs) [16,17].…”

Detection of 2-mm-long strained section in silica fiber using slope-assisted Brillouin optical correlation-domain reflectometry

“…Hence, many types of Brillouin-based measurement schemes have been developed, such as Brillouin optical time-domain reflectometry (BOTDR), [2][3][4][5] Brillouin optical frequencydomain reflectometry (BOFDR), 6) Brillouin optical correlation-domain reflectometry (BOCDR), [7][8][9][10] Brillouin optical time-domain analysis (BOTDA), [11][12][13][14][15] Brillouin optical frequency-domain analysis (BOFDA), [16][17][18] and Brillouin optical correlation-domain analysis (BOCDA). [19][20][21][22][23] While each scheme has its own merit and demerit, BOCDR is the only technique that operates by inherently one-end light injection and has high spatial resolution and cost efficiency, although it suffers from the trade-off relationship between the spatial resolution and the measurement range.…”