On The Possibility of Improving the Reliability of Communication in Fiber-Optic Systems with Spectral Compaction

In the article, the authors present a concrete example of a block diagram of a signal transmission device at WDM. Operation of this device with the representation of plots of pulse diagram of operation at standard characteristics of services and evaluation of their quality indicators depending on the fault tolerance in the whole system under study. Recommendations for practical use in various types of network topology are given. Spectral compaction technologies such as CWDM, DWDM, HDWDM, principles of construction of these technologies, as well as advantages and disadvantages are considered. The functional schemes of the signal transmission device and the functional scheme of the optical transceiver and the principle of operation of these devices are given. The frequency plan for CWDM systems is defined by ITU G. 694.2. The scope of CWDM technology is urban networks with a distance of up to 50 km. The advantage of this type of WDM systems is low (compared to other types) the cost of equipment due to lower requirements for the constituent equipment of the fiber optic network. The frequency plan for DWDM systems is defined by ITU G. 694.1. The field of application — backbone network. This kind of WDM systems has higher requirements for components than CWDM (radiation source spectrum width, source temperature stabilization, etc.). The impetus for the rapid development of DWDM networks was given by the appearance of inexpensive and efficient fiber erbium amplifiers (EDFA) operating in the range from 1525 to 1565 nm (the third window of transparency of quartz fiber). For simplicity, the model is limited to a frequency plan DWDM with a step of 100 GHz, and CWDM has eight main channels in the range of 1470-1610 nm. The calculations of reliability indicators of the basic version and the modified version of the signal transmission device are given