Recent Advances in Distributed Acoustic Sensing Based on Phase-Sensitive Optical Time Domain Reflectometry

Figure 4

Generation of high ER pulses for a high SNR ϕ-OTDR using the nonlinear Kerr effect [20]: (a) schematic of the generation, (b) CW light from laser, (c) sinusoidally modulated signal, (d) signal after pulse modulation, (e) signal after nonlinear Kerr medium, and (f) after filtering the nth order sideband ( in all cases stands for the power of the signal).

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