There are few reports on the mode-locking operation of indium sulfide (In₂S₃) in fiber lasers. In this paper, we experimentally demonstrate a harmonic mode-locked fiber laser in 2-μm region by taking advantage of an In₂S₃-based saturable absorber (SA). The In₂S₃-based SA has nonlinear optical modulation depth of 20.8 % and saturation power of 0.14 kW at 1930 nm. The fundamentally mode-locked solitons at 1938.59 nm with the 3-dB bandwidth of 5.04 nm, pulse width of 1.16 ps, and pulse repetition rate of 41.73 MHz are generated. The maximum harmonic-resonance frequency is 459 MHz (11th harmonic), which is the highest operating frequency that has been demonstrated in In₂S₃-based mode-locked fiber lasers as far as we know. The spectral and temporal characteristics of the output pulses are investigated versus harmonic order. The results prove that In₂S₃ possesses the characteristics of mode-lockers and could be a promising optical switch for ultrafast pulses generation.

关于硫化铟（In ₂ S ₃）在光纤激光器中的锁模操作的报道很少。在本文中，我们利用基于 In ₂ S ₃的可饱和吸收体 (SA)实验证明了 2 μm 区域的谐波锁模光纤激光器。基于 In ₂ S ₃的 SA 在 1930 nm 处具有 20.8% 的非线性光调制深度和 0.14 kW 的饱和功率。产生了 1938.59 nm 的基本锁模孤子，3 dB 带宽为 5.04 nm，脉冲宽度为 1.16 ps，脉冲重复率为 41.73 MHz。最大谐波谐振频率为 459 MHz（第 11 次谐波），这是 In _{2 中}已证明的最高工作频率据我们所知，基于S ₃的锁模光纤激光器。研究了输出脉冲的频谱和时间特性与谐波阶次的关系。结果证明In ₂ S ₃具有锁模器的特性，可能是一种很有前途的超快脉冲光开关。