Long-range Millimeter-resolution OFDR Based on 100 GHz Linear Frequency-sweep of Optical Source by Injection-locking Technique and Cascaded FWM Process

We demonstrate a high spatial resolution OFDR by utilizing injection-locking technique and cascaded FWM. A frequency sweeping span of ~100 GHz is obtained for realizing a 1.1 mm spatial resolution over 2 km measurement range.