Correlation optical time domain reflectometry based on broadband random optoelectronic oscillator

A correlation optical time domain reflectometry (COTDR) based on broadband random optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. Different from the conventional COTDR that utilizes an external feedback semiconductor laser as the chaotic source, the proposed scheme employs a random optoelectronic oscillator as the random signal source. With the assistance of randomly distributed feedback in the OEO caused by the random fiber Bragg grating, the generated signals have random and broadband characteristics, whose frequencies are not restricted by a fixed cavity length in the OEO. Due to the avoidance of relaxation oscillations in semiconductor chaotic laser, the generated random signal has a wide and flat spectrum as well as excellent autocorrelation features. The experimental results illustrate that the proposed COTDR can achieve a range-independent spatial resolution of about 10 mm and its dynamic range is at least 78.47 km.