High-Repetition-Rate Pulsed Yb-Doped Fiber Laser Based on Hybrid Plasmonic Microfiber Resonator

Mode-locking based on dissipative four-wave-mixing (DFWM) has been fundamental in producing pulses with repetition rates on the order of gigahertz, where comb filters and long nonlinear components are elemental. Here we demonstrate a gigahertz stable pulsed Yb-doped fiber laser based on the hybrid plasmonic microfiber knot resonator device. Output with repetition rate of 54.8 GHz at 1 μm waveband and 2.27 ps pulse-width is achieved. Unlike previous pulse generation mechanisms, the operation utilizes the nonlinear-polarization-rotation (NPR) effect introduced by the polarization-dependent feature of the device to increase intracavity power for boosting DFWM mode-locking. The easily fabricated versatile device acts as a polarizer, comb filter, and nonlinear component simultaneously, thereby introducing a novel application of microfiber resonator devices in ultrafast and nonlinear photonics.