A temperature-stabilized optical amplifier (100) comprises at least an erbium-doped waveguide (101) for amplifying optical signals; at least a first and a second pump sources (103, 104) for generating respective pump beams at a first and, respectively, a second pump wavelength (λ 1 , λ 2 ), said first and second pump wavelength being lower and, respectively, higher than 978 nm at an intermediate temperature of a predetermined range of temperature, and being subjected to drift as a consequence of temperature variations; and a pump distribution device (105), optically coupled to said pump sources for receiving said pump beams, and optically coupled to said at least an erbium-doped waveguide for feeding to said at least an erbium-doped waveguide a mixed pump radiation comprising at least a power fraction of each of said pump beams.