Research On TDM-PON Fiber Network Fault Detection Technology Based On Optical Feedback Semiconductor Laser Cavity Length

Time division multiplexing passive optical networks have been widely deployed in optical access networks due to their simple structure and low maintenance cost.Since the fiber is relatively fragile and prone to fracture,and the fiber network has many branches and the distribution of fiber is relatively dense,it becomes extremely important to obtain the specific branch and the exact location of the fault from multiple branches in the shortest time after the fault occurs.In order to solve this problems,researchers have proposed many detection methods,of which the most widely used is the optical fiber network detection technology based on Optical Time Domain Reflectometer.However,the optical time domain reflectometer has the disadvantage that the measurement distance and the measurement accuracy cannot be improved at the same time,and when the optical time domain reflectometer is applied to the fault detection of the optical fiber network,the branch cannot be directly positioned,and some auxiliary measures are needed.This undoubtedly makes the detection structure becomes complicated,high precision could not be combined with the fault detection means detecting a simple construction to meet the needs of operators.The ultra-wide bandwidth of chaotic laser signals and the characteristics of being sensitive to initial values make it possible to obtain higher resolution when applied to the detection of breakpoints in optical fiber networks.The chaotic laser generated by the optical feedback semiconductor laser can obtain the distance information between the laser and the feedback device after being processed by the chaotic laser correlation method.When a fiber failure occurs,Fresnel reflection occurs at the location of the failure.When the optical feedback structure is applied to fiber fault detection,the position of the fault is equivalent to a mirror.When the optical feedback structure is applied to the fault detection of the time division multiplexing passive optical network,it is only necessary to place a device that can reflect the detection signal at the end of the user branch,and add a length feature to the branch through the different lengths of the reflective cavity.When the fault occurs on the trunk road,all the reflection peaks disappear,and a new reflection peak appears at the fault location;when the fault occurs in he branch circuit,the corresponding reflection peak of the branch disappears,and a new reflection peak appears at the fault location reflection peak.Based on the above research results,this article has done the following work:(1)Introduce the working principle of time division multiplexing passive optical networks,and the existing problem of detection methods,and make a specific analysis of these methods.This paper introduces the detection principle and fault location method of the optical feedback semiconductor laser cavity length feature to realize the time division multiplexing passive optical network fault.(2)Constructed a long cavity multiple feedback semiconductor laser chaotic system model,based on this model,the feasibility of optical feedback semiconductor laser cavity length feature to realize time division multiplexing passive optical network fault detection was verified.At the same time,a series of simulation studies were carried out on some specific parameters of the method.(3)A four-branch time-division multiplexing passive optical network was constructed,and experimentally studied the fault of the time-division multiplexing passive optical network based on the multiple feedback semiconductor laser cavity length Positioning method,and achieved a target accuracy of centimeter level.