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.

As a member of the porous crystalline material family, metal organic framework (MOF) materials have been widely used in the fields of photodetection, photovoltaic cells, nonlinear optical devices, supercapacitors, and biological imaging. However, few reports about robust pulsed laser based on MOF‐derived nanomaterials especially the one with unique structure have been reported till now. In this paper, porous dodecahedron rGO‐Co3O4 is synthesized by calcining the MOF template and systematically analyzed. Interestingly, the rGO‐Co3O4 is successfully prepared as a saturable absorber (SA) by using the optical deposition method and the modulation depth of the rGO‐Co3O4 SA is 8.38%. Through different dispersion management, robust pulses with 1.5 µm dissipative soliton (DS) in the frequency domain and square wave pulse (SWP) in the time domain can be obtained in the erbium‐doped fiber laser based on rGO‐Co3O4 SA. The 3‐dB bandwidth and pulse duration of the DS are 6.81 nm and 62.01 ps, respectively. The pulse tuning range of the SWP is 1.24 ns ≈ 19.14 ns. It is worth mentioning that the threshold of the SWP is 53.72 mW, and the mode‐locked laser can be self‐started at the pump power of 72.04 mW. The experimental results show that the porous dodecahedral rGO‐Co3O4 material derived from MOF can be used as an excellent nonlinear optical modulator, providing a new choice for material processing.

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We demonstrate for the first time to our knowledge the use of Fe 3 O 4 nanoparticles for Q -switching a tunable mid-infrared (Mid-IR) Dy 3 + -doped ZBLAN fiber laser around 3 μm. The Q -switcher was fabricated by depositing the prepared Fe 3 O 4 nanoparticles solution onto an Au mirror. Its nonlinear optical response was characterized using a mode locked Ho 3 + / Pr 3 + -codoped ZBLAN fiber laser at 2.87 μm, and showed a modulation depth of 11.9% as well as a saturation intensity of 1.44    MW / cm 2 . Inserting the device into a tunable Dy 3 + -doped ZBLAN fiber laser, stable Q -switched pulses within the tunable range of 2812.4–3031.6 nm were obtained. When tuning the wavelength to 2931.2 nm, a maximum Q -switching output power of 111.0 mW was achieved with a repetition rate of 123.0 kHz and a pulse width of 1.25 μs. The corresponding pulse energy was 0.90 μJ. This demonstration suggests that Fe 3 O 4 nanoparticles are a promising broadband saturable absorption material for mid-infrared operation.

As a new emerging semiconductor with interlayer bandgap, lead selenide (PbSe) have broad prospects in the fields of electrocatalysis, photocatalysis, infrared optoelectronic devices, optoelectronics, and ultrafast photonics. Among them, ultrafast photonics is receiving a lot of attention due to its ultrashort pulse, strong peak power, narrow bandwidth, and high repetition frequency. Herein, the properties are systematically studied of PbSe through various characterization methods. The modulation depth of PbSe is up to 30%, and its saturation light intensity is 7.86 MW cm −2 . Using the evanescent field effect, nonlinear fiber-based photonics devices has been successfully prepared based on the PbSe nanosheet solution, which can increase the bearable pump power. The 36th picosecond harmonic mode-locked soliton molecule is generated in the erbium-doped fiber laser, which corresponds to a maximum repetition frequency of 222 MHz. The results show that the signal-to-noise ratio can reach up to 49.1 dB which is higher than most previous works by now. The results revealed the potential of PbSe as an excellent photonics material in applications such as nonlinear optics, ultrafast photonics equipment, photoconductive detectors, and light modulators.