报道了石墨烯可饱和吸收体作用于2 μm激光的被动调Q脉冲输出特性.采用线型谐振腔，掺铥光纤和石墨烯可饱和吸收镜分别作为增益介质和被动调Q器件，792 nm半导体激光器端面泵浦掺铥光纤，利用一组准直聚焦透镜将腔内光束会聚到石墨烯所在位置，成功实现了中心波长为1 958 nm的被动调Q脉冲输出.当泵浦功率为3.0 W时，获得了1.02 μs的最窄脉冲宽度，对应的平均输出功率为26 mW，脉冲重复频率为116 kHz，单脉冲能量为224 nJ，平均输出功率、脉冲宽度与泵浦功率近似呈线性关系.实验结果表明，石墨烯优良的可饱和吸收特性，可有效实现2 μm波段的被动调Q激光运转.

The output characteristics of graphenebased passively Qswitched pulses at 2 μm wavelengths were reported. On the basis of linear resonant cavity, Tm3+doped fiber and graphene saturable absorber mirror served as gain medium and passively Qswitched device respectively. Tm3+doped fiber was end pumped by 792 nm semiconductor laser. Light in the cavity was focused onto graphene membrane through a set of collimation and focusing lens. Passively Qswitched pulses centered at 1 958 nm wavelength were acquired successfully. The minimum pulse width of 1.02 μs was obtained when pump power rise to 3.0 W, and corresponding average output power of 26 mW, repetition rate of 116 kHz, single pulse energy of 224 nJ were obtained respectively. Furthermore, average output power and pulse width presented approximate linear relationship with incident pump power. The experimental results indicate that excellent saturated absorption characteristic of graphene is effective for passively Qswitched pulse operation at 2 μm wavelengths.