Dual-Waveband Self-Pulsed Laser at 3 $\mu$ m and 2.1 $\mu$ m

We report dual-waveband self-pulsing at 3 and 2.1 μm in a Ho-doped ZBLAN fiber laser, for the first time to our knowledge. In a linear cavity bi-directionally pumped at 1150 nm, stable 3- and 2.1-μm self-pulsing in the kHz region with a ns~μs scale was simultaneously achieved. Their behaviors depending on the pump power were similar to Q-switching and gain-switching, respectively. The preliminary experimental results indicated that the origin of the 3-μm self-pulsing was probably the excited state re-absorption process
⁵
I
₇
→
⁵
I
₆
and the 2-μm self-pulsing should be induced by the 3-μm self-pulsing by the way of gain-switching. At the maximum pump power of 8.72 W, the largest output power of 917.5 mW (3 μm)/414.7 mW (2.1 μm) and pulse energy of 5.87 μJ (3 μm)/2.62 μJ (2.1 μm) were gained. This demonstration provides an alternative way for 3- and 2.1-μm dual-waveband short pulse generation in a simple scheme, which can find direct medical applications.