60 nm Bandwidth, 17 nJ Noiselike Pulse Generation from a Thulium-Doped Fiber Ring Laser

We report on the generation of high-energy noiselike pulse in a passively mode-locked thulium-doped fiber ring laser based on the nonlinear polarization evolution technique. A newly developed heavily thulium-doped germanate glass fiber was used as the gain medium. By properly rotating the polarization controllers, the 17.3 nJ noiselike pulse with 60.2 nm spectral bandwidth was obtained at the fundamental pulse repetition frequency of 6.37 MHz. Correspondingly, the maximum average output power was 110 mW. The direct output of high-energy noiselike pulse from the thulium-doped fiber laser provides a good candidate of pulse source for some important applications such as the supercontinuum generation at mid-infrared wavelength range and optical metrology.