Coherent optical time domain reflectometry using three frequency multiplexing probe

This paper proposes a multi-frequency probe based coherent optical time domain reflectometry (MFP C-OTDR). In the new C-OTDR scheme, single frequency light is converted to multi-frequency light and three multiplexing frequencies with the same power level are adopted as the probe, while local oscillator (LO) remains original single frequency. Coherent detection between the backscattered Rayleigh light of the multi-frequency probe and LO generates many intermediate frequencies (IFs), and three IFs corresponding to the three dominant frequencies of the probe are simultaneously measured and processed. Experimental results indicate that the MFP C-OTDR can triple the measurement number compared with conventional single frequency probe based C-OTDR, which brings much quick fading noise reduction capability and a 1.2 dB single way dynamic range (SWDR) enhancement. (C) 2012 Elsevier Ltd. All rights reserved.