Functional Porous MOF-Derived CuO Octahedra for Harmonic Soliton Molecule Pulses Generation

Metal-organic frameworks (MOF) or their derivatives have attracted much attention in recent years due to exciting properties such as high specific surface area, adjustable pore size, and easy functionalization, which makes them have unique advantages in the fields of catalysis, energy storage, optoelectronics, and so on. However, the study of them in the fields of nonlinear optics and ultrafast photonics is still in its early stage. Here, by annealing the MOF template, porous MOF-derived CuO octahedra are prepared and applied to the above fields. Experiments show that CuO octahedra possess an excellent nonlinear optical absorption capacity in the near-infrared band. When it is used as a saturable absorber (SA) to the fiber lasers, high order harmonic soliton molecules with a repetition frequency up to 238 MHz can be obtained that make sense for optical frequency combs and optical communication. Besides, the dynamic evolution of the harmonic soliton molecule is explored. This work pioneers the application of MOF-derived metal oxide polyhedra as SAs in fiber lasers and expands the application fields of MOF-based materials. Moreover, this kind of emerging microstructured polyhedral SA, prepared by the new method, provides researchers with a new choice beyond quantum dots, nanoparticles, and 2D nanosheets/nanofilms.