Fiber fault detection in WDM-PONs based on a random optoelectronic oscillator

A method for multichannel fiber break detection in wavelength-division-multiplexed (WDM) passive optical networks (PONs) based on a random optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. By incorporating a random chirped fiber Bragg grating (R-CFBG) into the OEO loop, the inherent OEO cavity length limitation in conventional designs is successfully overcome. The implemented architecture generates a broadband random optical signal with a 3 dB bandwidth of about 10.5 nm, covering multiple WDM channels while demonstrating superior autocorrelation properties. After passing through WDM, the broadband random optical signals undergo selective filtering, ensuring that the filtered optical signals in each corresponding channel retain their well-preserved randomness. Experimental results indicate that this method achieves a distance-independent spatial resolution of 9 mm and a dynamic range of approximately 43.15 km. Moreover, it is experimentally verified that mutual interference does not occur among multiple channels during the detection process.