In this paper, we demonstrate the transmission spectral and surrounding refractive index (SRI) sensing performance of long-period fiber gratings (LPFGs) at 2 μm waveband. The cladding modes operat…
As the most common member of the underground pipeline, optical cable has already spread throughout the urban region. By combining the distributed acoustic sensing (DAS) system with the existing opt…
Correcting the nonlinear frequency sweep of the tunable laser source in optical frequency domain reflectometry (OFDR) is critical for accurate measurement. It is common to correct the nonlinear fre…
In the coherent Φ-OTDR system with small laser-frequency-drift less than 50 kHz, the phase change in the quiet region without external perturbation is theoretically deduced to be linear with the f…