Femtosecond mode-locking of a fiber laser using a CoSb₃-skutterudite-based saturable absorber

We experimentally demonstrate an ultrafast mode-locker based on a CoSb₃ skutterudite topological insulator for femtosecond mode-locking of a fiber laser. The mode-locker was implemented on a side-polished fiber platform by depositing a CoSb₃∕PVA composite. The measured modulation depth and saturation power for the transverse-electric mode input were ∼5% and ∼8.7 W, respectively, and ∼2.8% and ∼10.6 Wfor the trans-verse-magnetic mode input. By incorporating this mode-locker into an erbium-doped fiber-based ring cavity, we were able to readily generate mode-locked, soliton pulses having a pulse width of ∼833 fs at 1557.9 nm. The 3-dB bandwidth of the output pulses and time-bandwidth product were ∼3.44 and 0.353 nm, respectively. To the best of the authors’ knowledge, this is the first demonstration of the use of a skutterudite-based saturable absorber for femtosecond mode-locked pulse generation.