High-power 120 fs pulses at 1.23 GHz from a single-mode Er-Yb-doped Fiber laser

We present a compact single-mode Erbium-doped master oscillator power amplifier (MOPA) fiber laser that can directly produce 100 fs pulses at 2.2 W and 120 fs pulses at 4.5 W average power. The laser operates at a 1.2 GHz pulse repetition rate, with a central wavelength around 1550 nm. The laser system consists of a passively mode-locked oscillator with a repetition rate of 77.6 MHz and an average power of 16.3 mW. Using a repetition rate multiplier consisting of six 50/50 couplers, we achieved pulses with a repetition rate of 1.23 GHz. The output was subsequently increased to approximately 4.5 W average and 30 kW peak power using a cladding pump 10/125 Erbium-Ytterbium (Er-Yb) doped gain fiber. Through numerical modeling of pulse generation within the laser, we achieved a very good agreement with experimental results, inferring the pulse dynamics and its power scaling limitations.