Nonlinear Effects and Remote-Pump Power Budget in Erbium-Doped Fiber Amplifiers for Long-Reach TDM Fiber-Optic Sensor Interrogation

Remotely pumped erbium-doped fiber amplifiers (EDFAs) can extend fiber-optic sensor interrogation reach without electrical power at the remote site, but their power budget is constrained by pump attenuation, amplified spontaneous emission and fiber nonlinearity. This work develops a rate-equation and nonlinear-propagation framework for a two-stage remote EDFA (1550 nm signal, 1480 nm pump) under CW and pulsed TDM operation, using two independent platforms. Over a 40 km feeder, Brillouin scattering is the dominant limitation, reducing gain from 12.29 to 9.43 dB and raising noise figure from 5.14 to 5.88 dB, while Kerr, Rayleigh and Raman effects are minor. An EDF-length sweep identifies an optimum near 5–9 m, and pulsed operation reaches up to 24.81 dB gain and 4.29 dB noise figure, the platforms agreeing within 0.7 dB. Extending the feeder from 40 to 150 km, the architecture keeps a clear edge over a single-stage design — 17.2 dB gain at 100 km versus 11.0 dB — while needing less pump power and delivering more received power at every reach tested. Broadening the pump linewidth to about 10 GHz captures most of this SBS-mitigation benefit; pushing further brings little additional gain. The results provide simulation-based design guidelines for remotely powered EDFA repeaters in TDM fiber-sensor networks, pending experimental confirmation.