Improving the Spatial Resolution of an OFDR Based on Recirculating Frequency Shifter

We demonstrate a novel method for obtaining high spatial resolution optical frequency domain reflectometry (OFDR) utilizing recirculating frequency shifter for broadening the optical frequency sweeping. Twelve times broadened optical frequency sweeping is achieved. We obtain 0.97 cm spatial resolution over 710-m measurement range with modulation frequency sweeping span of 882 MHz. Such a spatial resolution corresponds to a frequency sweeping span of 10.31 GHz. The experimental results indicate that the measurement range can be extended to 10 km, based on the proposed method.