Generation of a 33.9 nJ, 91 fs pulse at 920 nm from an Nd-doped fiber laser

High-energy, sub-100 fs pulses at 920 nm have significant applications in various scientific fields. Compared to the Ti-sapphire laser and nonlinear frequency conversion of ultrafast fiber lasers at other wavelengths, the direct generation of a 920 nm femtosecond pulse using an Nd-doped fiber laser offers a more effective approach. In this study, an all-polarization-maintaining (PM) Nd-doped fiber laser system is developed. Through precise optimization of the system parameters, including the pre-chirp group-delay dispersion (GDD) and pump powers of the two-stage amplifiers, an average output power of 2.07 W is achieved. The pulse can be compressed to 91 fs by using a grating pair. The compressed pulse has an average output power of 1.52 W, corresponding to a pulse energy of 33.9 nJ. The proposed system demonstrated excellent power stability over 10 hours. To the best of our knowledge, this work represents the highest pulse energy for sub-100 fs pulse at 920 nm directly generated from an Nd-doped fiber laser system, providing a reliable laser source for practical applications.