Phase-noise and shot-noise limited operations of low coherence optical time domain reflectometry

摘要: This letter shows theoretically and experimentally that Fresnel end reflection of the waveguide under test degrades sensitivity low coherence optical time domain reflectometry (OTDR). Optical mixing reference light in OTDR produces phase noise proportion to reflectivity. With balanced detection technique, excess photon is subdued becomes dominant source degradation. At 3.2% 300 μA mean photocurrent, floor due −138 dB/Hz. By reducing fiber with matching oil, a shot‐noise limited −140 dB at 3 Hz bandwidth has been demonstrated submillimeter resolution.