High spatial resolution reflectometry for optical subscriber networks by synthesis of optical coherence function with measuremet range enhancement

We newly propose an optical coherence domain reflectometry for optical subscriber networks with measurement range enhancement, This reflectometry is based on our own technique to synthesize an optical coherence function. An optical switch after a light source generates optical pulses, which select the measuring region, in which one coherence peak is scanned with high spatial resolution. An optical fiber loop delay line including a frequency shifter is placed in a reference-path of the interferometer. In this method, the measuring region could be easily changed by the hetelodyne intermediate frequency selected at the electronic band pass filter, In the basic experiments. the reflections at 5 km distance are measured with a spatial resolution of 8 cm, and the change of the measuring region is successfully demonstrated.