Multi-watt picosecond 1.7 µm Tm-doped fiber laser amplification system

We report on a multi-watt, high-repetition-rate picosecond 1.7 µm Tm-doped fiber (TDF) laser amplification system. The seed oscillator is a figure-9 passively mode-locked TDF laser, which delivers a pulse train with a center wavelength of 1738nm and a fundamental repetition rate of ∼85 MHz. After a pre-amplifier and two stages of TDF amplifiers, the output power can be amplified to 5.2 W at a pump power of 10 W, corresponding to a slope efficiency of 52.1%. The output pulse duration is 33.87 ps and the pulse energy is 61 nJ. These results demonstrated that it is an effective method for achieving high-power ultrafast fiber laser source at 1.7 µm waveband, which would be a promising candidate for diverse applications such as polymer welding, bioimaging, mid-infrared laser generation and medical applications.