ESTIMATION OF THE OPTIMAL POWER LEVELS OF TRANSMITTERS IN FIBER-OPTIC TRANSMISSION SYSTEMS WITH FREQUENCY DEVISION CHANNELS
Vardges A. Vardanyan, Siberian State University of Telecommunications and Informatics, Novosibirsk, Russia, vardgesvardanyan@mail.ru
Abstract
Currently, optical access networks are experiencing an explosive demand for broadband multimedia services, cloud computing services and information content storage. This circumstance, on the one hand, forces the developers of telecommunication equipment to find solutions which guarantee the required high data transfer rate of users, and, on the other hand, use cost-effective user-class equipment. To solve the problems associated with an increase in the capacity of optical access networks, it is proposed to use frequency division multiplexing not only in the optical band, but also in the radio band. In the case of frequency division multiplexing in the radio frequency band, multichannel signals are formed, where spectral effective multi-level signals of different modulation formats are transmitted in channels. Using the frequency multiplexing of such multichannel signals in the optical band, an increase in the transmission capacity of the transmission system is achieved. However, an increase in channel loading leads to the appearance of nonlinear phenomena in an optical fiber, which limits the further increase in transmission capacity of the transmission system. The work deals with the transmission of frequency multiplexed signals of the formats BPSK, QPSK, ASK, QAM over a fiber operating in a nonlinear mode. It is shown that the optical power levels of transmitters are limited from below by spontaneous noise of an optical amplifier, and from above by nonlinear phenomena. When forming up to 80 optical frequency multiplexed channels by the BPSK, QPSK, ASK modulation formats, four-wave mixing becomes the limiting factor, and for channels with the QAM formats – phase cross-modulation. A further increase in the number of optical channels leads to the fact that stimulated Raman scattering is added to these limiting nonlinear phenomena. Formulas are given that allow to calculate the optimal optical power levels of transmitters depending on the required parameters of the transmission system: the transmission distance, the number of spectral and subcarrier channels, their modulation formats and the frequency interval between them.
Keywords: FDM, FWM, XPM, SRS.
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Information about author:
Vardges A. Vardanyan, Associate Professor, Candidate of Engineering Sciences, Department of Telecommunications and Optical Systems,
Siberian State University of Telecommunications and Informatics, Novosibirsk, Russia