A METHOD OF TAKING THE SPECTRAL CHARACTERISTICS OF THE LASER-EMISSION INTO ACCOUNT IN AN OPTICAL-FIBER TRANSMISSION-SYSTEM

The wide introduction of optical-fiber transmission systems into communications networks has given rise to the need to predict the data-transmission quality in digital linear optical channels with satisfactory accuracy, taking into account the actual characteristics of the components of the transmission system. When modeling the transmission of signals along an optical-fiber transmission system the root mean square width of the spectral line of the laser sigma(l) is usually specified as the spectral characteristic of the source of optical radiation [1, 2], ignoring the fact that actual semiconductor lasers employed in optical-fiber transmission systems are multimode and have a line spectrum with energy bands separated by intervals of the order of 0.2-0.4 nm [3, 4]. We will consider a method of taking into account the actual experimentally determined spectral characteristics of the radiation sources employed in optical-fiber transmission systems in distorting the digital signals transmitted along digital linear optical channels. The method uses the mathematical model of a digital linear optical channel proposed in [5, 6].