2-$\mu\hbox{m}$ Tm-Doped All-Fiber Pulse Laser With Active Mode-Locking and Relaxation Oscillation Modulating

We report on the actively mode-locked and relaxation-oscillation-modulated 2- μm all-fiber laser, using an electronic optical phase modulator with fiber pigtail. Linear-cavity and ring-cavity fiber lasers with Tm-doped fiber were set up with a center wavelength around 1.95 μm. Actively mode-locked stable pulse train was generated with a repetition rate of 11.884 MHz (linear cavity) and 12.099 MHz (ring cavity), and the duration of the pulse was 816 ps and 446 ps, respectively. The stable pulse train with a duration of 5.885 μs and a repetition rate of 4-18 kHz was generated by actively modulating the relaxation oscillation of the linear-cavity fiber laser. Similar results for the ring-cavity fiber laser were 1.554 μs and 6-26 kHz, respectively. All the stable pulse trains' energy fluctuations were less than 7%.