Sub-100  fs all-fiber mode-locked laser at high repetition rates for THz spectroscopy

Ultrafast fiber lasers, as key enablers of powerful THz pulse generation, drive the recent advancements in THz technologies, specifically in THz-time domain spectroscopy. The research focuses on the generation of sub-100 fs pulses at telecom wavelengths (1500-1600 nm) suitable for high-repetition-rate THz pulse generation through photoconductive antennas. This work presents experimental results substantiated by numerical simulation, on both artificial saturable absorber (nonlinear polarization rotation) and physical saturable absorber (SESAM)-based mode-locked fiber lasers delivering sub-100 fs at a high fundamental repetition rate range of 60-80 MHz.