1030-nm passively Q-switched ytterbium-doped fiber laser using excited-state absorption of thulium fiber

We demonstrated a pulsed ytterbium all-fiber laser passively Q-switched using excited-state absorption of thulium fiber and a mode-field-area mismatch. The absorption cross section of the excited state ³ F₄ was measured and deter-minedtobethe key factor inducing pulsing, and it was much higher than that of the ground state ³ H₆ over 0.95-1.15 μm. By successfully realizing the pulsed laser at 1030 nm, which is the most critical wavelength for Q-switching, we verified that the excite state ³ F₄ of Tm³⁺ could be a full-range saturable-absorber Q-switch for a Yb fiber laser over 1.0-1.15μm.