Sub-200 fs, 344 MHz mode-locked Tm-doped fiber laser

We demonstrate a compact, self-starting mode-locked thulium-doped fiber laser based on nonlinear polarization evolution (NPE), with a fundamental repetition rate of ∼344MHz and a pulse duration of ∼160fs. The generated pulses centered at ∼1975nm have a maximum output power of ∼560mW, corresponding to a pulse energy of ∼1.63nJ. To the best of our knowledge, the achieved repetition rate represents the highest value of fundamentally NPE mode-locked fiber lasers at ∼2µm, while the average output power is also higher than the previously reported 2 µm ultrafast single-mode fiber oscillators. The timing jitter in the integrated range [5 kHz, 10 MHz] and the integrated relative intensity noise in the range [10 Hz, 10 MHz] reach ∼35fs and ∼0.009%, respectively. Our high-performance laser is an ideal candidate for various applications, including mid-infrared frequency metrology and high-speed optical sampling.