Passively Q-switched Tm^3+-doped silica fiber lasers

Abstract

By splicing on a length of ${\text{Ho}}^{3+}$-doped silica fiber onto a diode-pumped double-clad ${\text{Tm}}^{3+}$-doped silica fiber, stable passive Q switching of the ${\text{Tm}}^{3+}$-doped silica fiber laser is demonstrated. The formation of Q-switched pulses was found to depend on both the length and the position of the ${\text{Ho}}^{3+}$-doped silica fiber that was inserted into the fiber laser cavity. For stable Q-switched pulse generation, ${\text{Ho}}^{3+}$-doped silica fiber lengths shorter than twice the absorption depth must be used. For long ${\text{Ho}}^{3+}$-doped silica fiber lengths, randomly generated pulses are observed at operating wavelengths longer than $2090\text{\hspace{0.17em} nm}$, which are attributed to intracavity pumping of the ${\text{Ho}}^{3+}$-doped silica fiber.