The generation of noise-like pulses and various solitons with CuO nanorods as a broadband saturable absorber

Copper oxide (CuO) nanorods exhibit unique photoelectric properties due to their high surface area, excellent volume effect, and quantum confinement effect, which have also attracted wide attention in the application of ultrafast photonics. In the present work, CuO nanorods were successfully prepared by a simple synthesis strategy and characterized in detail. The density of electron states (DOS) and the band structure of CuO were predicted by the first principles simulation method. The nonlinear optical response parameters of CuO nanorods were determined by a twin-balanced detector system. Based on the excellent nonlinear optical response, CuO nanorods were exploited as saturable absorbers (SAs) to achieve the noise-like pulse (NLP) mode-locking operation in the erbium (Er)-doped fiber laser (EDFL) at 1552 nm and ytterbium (Yb)-doped fiber laser (YDFL) at 1038.5 nm. Additionally, by shortening the cavity length of EDFL and finely optimizing the intracavity polarization, various solitons, and dual-wavelength solitons were also observed. Moreover, the dynamic evolution of spectra and pulses in YDFL was simulated using scalar nonlinear Ginzburg-Laudau equation (GLE). Our work well demonstrated the broadband and high-efficiency saturable absorption in CuO nanorods, paving the path for investigating multi-soliton dynamics and broadband ultrafast photonics.