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

The wide introduction of optical-fiber transmission systems into commu nications networks has given rise to the need to predict the data-tran smission quality in digital linear optical channels with satisfactory accuracy, taking into account the actual characteristics of the compon ents of the transmission system. When modeling the transmission of sig nals along an optical-fiber transmission system the root mean square w idth of the spectral line of the laser sigma(l) is usually specified a s the spectral characteristic of the source of optical radiation [1, 2 ], ignoring the fact that actual semiconductor lasers employed in opti cal-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 expe rimentally determined spectral characteristics of the radiation source s employed in optical-fiber transmission systems in distorting the dig ital signals transmitted along digital linear optical channels. The me thod uses the mathematical model of a digital linear optical channel p roposed in [5, 6].