FIELD: optical fibres. SUBSTANCE: proposed optical amplifier is meant for fibre-optical telecommunication lines designed to transmit signal within certain range of wave lengths. This amplifier includes fluorescence-activated optical fibre 6 with addition of erbium composed of two cores 11 and 12, 101 and 102. One of cores 11, 101 is connected to light guiding fibre 4 where transmitted signal should be amplified and multiplexed with energy of light pumping and to output fibre intended for transmission of amplified signal. Second core 12, 102 is optically coupled to first core and is capable of absorption of spontaneous radiation of erbium which in opposite case would be source of noise that in the long run gives possibility to amplify passed signal within band of wave lengths corresponding to rated range of industrially manufactured and commercially accessible laser signal radiators. EFFECT: improved operational characteristics of amplifier. 25 cl, 13 dwg
