We report herein on the development of a linearly polarized, single-frequency tunable laser system producing more than 10 W in the 1550 nm range, using a two-stage erbium/ytterbium co-doped fiber-based master oscillator power amplifier (MOPA) architecture. The all-fiber MOPA provides an ultralow intensity noise of −160dBc/Hz beyond 200 kHz between 1533 and 1571 nm ( Δλ=38nm ) at full output power and a minimum optical signal to noise ratio of 38 dB. A good stability is obtained over 4 h at maximum power for several wavelengths with peak-to-peak fluctuation less than 3% and rms below 0.5%.