Mid-infrared nanosecond pulse generation from a graphene modulated Er³⁺-doped fluoride fiber laser

We demonstrate a 2792.0 nm passively Q-switched Er³⁺-doped fluoride fiber laser using a graphene saturable absorber mirror (GSAM). Through optimizing the cavity design and the parameters of the GSAM, stable pulses are obtained with a repetition frequency ranging from 60.2 to 221.8 kHz. The shortest pulse duration is 238.2 ns, which, to the best of our knowledge, is the shortest passively Q-switching pulse obtained in 3 μm mid-infrared wavelength region. The maximum average output power is 535 mW, and the single pulse energy is 2.53 μJ. Further improvement of the pulse energy and pulse width is possible by optimizing the bleaching energy of the GSAM. (author)