Plasmonic gold-enhanced GaAs for femtosecond laser generation

Surface plasmon resonance (SPR) can significantly enhance the local electromagnetic fields, facilitating the interaction between light and matter at the nanoscale. However, its ultrafast photonics application in lasers remains unexplored, especially for femtosecond pulsed laser generation. In this work, we investigate the femtosecond pulse generation based on SPR-enhanced nonlinear absorption characteristics in GaAs for the first time, to the best of our knowledge. The gold nanoparticles (GNPs)+GaAs bilayer saturation absorber (SA) decorated on the tapered fiber generates a modulation depth of 2.02% and a saturable intensity of 3.13 MW/cm 2 . Stable mode-locked pulses can be obtained in an erbium-doped fiber cavity, as demonstrated here. The signal-to-noise ratio (SNR) of the pulses is 75 dB and the shortest pulse duration can reach 384 fs, highlighting the potential of the SPR effect in manufacturing ultrafast optical devices.