Dynamic Interaction Process Analysis Between Failure-Detecting Light Pulse and 2D Optical Encoder in Link Health Detection System for PON

We explore the dynamic interaction process between the failure-detecting light pulse and fiber Bragg grating (FBG) based two-dimensional (2-D) optical encoder in a link health detection system (LHDS) for a passive optical network (PON). The dynamic interaction model for PON-LHDS with a 2-D optical encoder supporting 2 m −1 users is derived by discussing the overlap between the failure-detecting light pulse spectrum and the FBG reflection spectrum, where m is the number of the failure-detecting light sources. A series of received light pulses for PON-LHDS with six wavelength channels involving 32 users are obtained based on the model, considering the variation of the FBG parameters. The simulation results show that the central wavelength difference between the failure-detecting light pulse and the coding FBG is the key factor affecting a system performance that 0.1 nm central wavelength difference will reduce the equivalent reflection coefficient to 0.89 and result in a 6.56-dB peak power difference of the coded signal. The PON-LHDS with a 32-user 2-D optical encoder is a setup, and the experiment results indicate that the peak power of the coded signal between two channels has a 2.8-dB difference due to the central wavelength difference, consistent with the calculation results of the dynamic interaction model.