Nonlinear effects in φ-OTDR system

Recent trends in long distance phase-sensitive optical time-domain reflectometer (φ-OTDR) have led to a proliferation of studies on nonlinear effects. We explores stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), selfphase modulation (SPM) and modulation instability (MI) in the φ-OTDR system both theoretically and experimentally. Results show that the analytical model of above nonlinear effects have significance for practice reference, except for MI in the case of long distance. The depletion of power and amplified spontaneous emission power density as the most effective consequences of modulation instability must be taken into account. Compared with theoretical analysis, numerical simulation provides more accurate results, and experiments support the existence of unreported intrinsic spectral component of MI around the signal.