Carbon Nano-onions as Saturable Absorbers for Pulsed Fiber Lasers

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.