High pulse energy picosecond erbium-doped fiber oscillator with near-Fourier-limited pulse duration

We report a high-pulse-energy, narrowband erbium-doped fiber (EDF) laser oscillator mode-locked by a semiconductor saturable absorber mirror (SESAM), delivering pulses with a nearly Fourier-transform-limited duration. The oscillator adopts a linear cavity configuration, in which linear loss is intentionally introduced by splicing polarization-maintaining (PM) fibers with mismatched core diameters and geometries. This design preserves the polarization state of the output while effectively suppressing multi-pulsing behavior under high pump power. The system delivers a pulse duration of 14.98 ps, a central wavelength of 1560.19 nm, a 3 dB spectral bandwidth of 0.20 nm, and an average output power of 16.30 mW. To the best of our knowledge, the achieved single-pulse energy of 937.86 pJ is the highest ever reported among SESAM mode-locked EDF oscillators with nearly transform-limited pulse durations. Following single-stage amplification, the output power is increased to 94.30 mW. The spectral linewidth broadened marginally from 0.20 nm to 0.21 nm, indicating minimal chirp and excellent spectral integrity. Long-term measurements confirm stable operation. The compact all-fiber configuration, combined with high pulse energy and near-transform-limited performance, makes this laser a promising candidate for use as a seed source in high-power MOPA systems and advanced nonlinear optical applications.