All-fiber noise-like pulse generation based on Yb-doped fiber and nonlinear fibers operating around 1040–1060 nm wavelengths

We demonstrate a compact all-fiber passively mode-locked ytterbium-doped fiber (YDF) laser that generates high-quality noise-like pulses (NLPs) via nonlinear polarization rotation. The system employs a 976 nm laser diode for pumping and features a fully fusion-spliced cavity, eliminating alignment-sensitive free-space components. To enhance nonlinear effects and ensure stable NLP generation, we explored several highly nonlinear fiber configurations, including ultra-high numerical aperture (UHNA3) fiber and photonic crystal fiber (PCF) with a zero-dispersion wavelength at 760 nm. The laser exhibits emission in the 1040–1060 nm wavelength range, with an average output power tunable from 20 mW to 35 mW depending on the cavity configuration. The best performance was achieved with a hybrid configuration consisting of a 20-cm PCF segment sandwiched between two 10-cm UHNA3 fiber segments, producing stable mode-locking at 1042.8 nm with a 31.5 mW average output power and pulses featuring a 23.05 ps envelope with 105.1 fs substructures. Compared to previously reported systems based on nonlinear polarization rotation, our design achieves significantly shorter pulse durations and more symmetric spectra, all while maintaining a robust, alignment-free architecture. These results highlight the importance of nonlinear enhancement and dispersion management in efficient pulse shaping and broadband spectral generation. Owing to its stability, compactness, and superior pulse quality, the proposed laser shows strong potential for applications in supercontinuum generation, ultrafast metrology, optical communications, and quantum photonics.