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Titanium nitride (TiN) with outstanding physical and chemical properties, has earned as much attention. However, few studies has been conducted on the ability of TiN in ultrafast photonics field. In...

The metal‐to‐insulator transition behavior and the fast and reversible phase transition behavior in vanadium dioxide (VO2) have attracted widespread attention to study various potential applications. However, few studies have been focused on its nonlinear properties and applications in the pulsed laser field. Here, the authors report the design and synthesis of monoclinic nano‐VO2(M) saturable absorber with broadband absorption which spans the entire near‐infrared region, and high optical nonlinearity which is much higher than those of carbon nanomaterials, gold nanocrystals, and Cu1.8S nanocrystals, as measured in the same condition. The nano‐VO2(M) optical modulators are integrated into the fiber laser cavities, and demonstrate wideband Q‐switching operations at 1, 1.56, and 2 µm and mode‐locking operation at 2 µm, with a pulse duration of 765 fs. This work first reveals the outstanding nonlinear optical properties of nano‐VO2(M) and lays a foundation for its development in advanced nonlinear optical and photonic devices.

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As a type of carbon-based material, zero-dimensional carbon nano-onions (CNOs), with outstanding physical and chemical properties, have attracted enormous attention. However, the performance of CNOs has not yet been verified in ultrafast photonics. In this work, we demonstrated broadband pulse generation induced by CNO modulators. CNOs were synthesized by the chemical vapor deposition technique with a diameter of ∼45 nm, which presented linear and nonlinear optical response properties. As the fabricated CNO film was embedded into the erbium-doped fiber laser as the saturable absorber, a Q-switched laser operating at 1565 nm was achieved. To further verify the potential of the CNO modulator, we then proposed a combination of CNOs and D-shaped fibers as the optical modulation platform. Ultrafast fiber lasers were achieved at 1562 and 1932 nm with good stability and a high damage threshold, respectively. Our results provide a channel for carbon-based materials in nonlinear optics and ultrafast photonics.