Tm–Ho Co-Doped Fiber Saturable Absorber Based All-Optical Active Q -Switching

We build an all-optical, all-fiber actively Q -switched Er-doped fiber laser with a simple ring cavity. Active Q -switching is attained by saturating a section of 34 cm Tm–Ho co-doped fiber saturable absorber with a 1550 nm pulsed fiber laser. The repetition rate of the pulsed output is 30 kHz determined by that of the subsidiary pump. The maximum pulse energy generated is about 80 nJ with a pulse duration of 2.07 μ s. The line width of the pulsed output is only 0.054 nm limited by the resolution capability of the spectrum analyzer.