Phase Noise Cancelled OFDR With cm-Level Spatial Resolution Using Phase Diversity

Optical frequency domain reflectometry (OFDR) has high spatial resolution and high sensitivity compared with optical time domain reflectrometry, provided the phase noise of optical source is cancelled. A new method was proposed to cancel phase noise in the OFDR. The proposed method detects short-distance and long-distance breakpoints with high spatial resolution. Double side band with a suppress carrier modulation was used with phase diversity detection. Experiments confirmed that the proposed method was achievable. Breakpoints at approximate distance 120 m were detected as short-distance breakpoints and ~20 as long distance. Performance of the proposed method has been further demonstrated by measuring expansion in fiber length due to change in temperature.