Proposal of OCDR based on periodic pseudo-random modulation

We propose and experimentally demonstrate an optical correlation-domain reflectometry (OCDR) method based on periodic pseudo-random modulation (PPRM). In conventional OCDR systems that employ sinusoidal modulation, additional “noise peaks” sometimes appear before and after the true reflection peak. Here, we show that PPRM effectively suppresses these unwanted noise peaks. Moreover, without introducing extra hardware, we achieve a measurement range of 3 km and a spatial resolution of around 5 cm—a performance level previously unattainable under standard OCDR conditions.