FIELD: fiber-optic communications. SUBSTANCE: low-noise optical amplifier 2 with active fiber has laser radiating substance 3 connected to optical fiber of communication line 1 and accepting light therefrom with trans mission wavelength, in which active fiber 6 is also fed from light source with pump wavelength and its length corresponds to frequency absorption of pump light directly introduced in it; placed after active fiber 6 is selective mirror 8 that reflects light with pump wavelength and is transparent for light with transmission wavelength; mirror 8 is better to have optical demultiplexor 9 adapted to split pump wavelength into two output fibers 11, 12; fiber 7 has mirror 13 on its end carrying pump wavelength that reflect at least pump wavelength. EFFECT: reduced noise, improved design. 7 cl, 5 dwg
