Design And Development Of Optical Fiber Protection System

From last century when fiber and laser with excellent performance were invented to the recent years when submarine optical fiber cable and ordinary fiber are being used as the main channel of information transmission widely, the human has entered the era of optical fiber communications. Optical fiber is accepted by our information society mainly because of its larger transmission capacity, higher reliability and lower transmission loss. On one side, the optical fiber communication technique meets our human's requirement for information with large capacity. On the other side, the optical fiber communication technique is also propelled by our human's needs. However, we have transferred our attention to the quality of optical fiber instead of only staring at the capacity. Now, the transmission situation is not ideal for optical fiber communication system. Beside the damage of optical devices, the optical fiber communication is always cut down by optical fiber's break caused by earthwork, rodents, fire, shooting and so on.This thesis mainly discusses the principles and compositions of the fiber protection system, just to overcome the problems caused by optical fiber's break. The fiber protection system provides redundancy protection by providing backup lines or searching available lines. Unnecessary losses could be avoided if backup lines be selected in time. And the key point is to get a reliable switching standard which concerns about the accuracy and sensitivity for the optical power from optical fiber cable. Right now, there are many disadvantages for fiber protection principles being used, just like low accuracy, less sensitivity, small detecting range, fixed threshold once set and so on.To solve these drawbacks above, this thesis designs and develops a new fiber automatic protection system with lager detecting range and higher accuracy using logarithmic amplifier, micro-processing chips and optical devices on the basis of'1+1' fiber protection system. Additionally, network communication module is added to realize the communication between the remote computer and the on-line detecting module by transplanting uIP to micro-processing chips. What's more, this paper analyses and fits the test data and then amends the system in order to improve the accuracy. After running and testing, the optical power of the system designed can reach a range of-60-4dBm, and the switching time is at the lever of many micro-seconds. Compared with working by communicating with remote computer, it needs less time to response with faults just working alone. And the switching time reaches ITU-T's standards.An optical fiber automatic protection scheme is proposed in this thesis, and it was designed and realized. The results showed that the system ran stably and reliably, with better performance in sensitivity and larger measurement range than current schemes being used now. So the work is very important for improving the reliability of optical communication networks.