Enhanced Nonradiative Charge Recombination in Microfiber-Based Bismuthene.

After the first report of a graphene-based passive mode-locking ultrafast fiber laser, two-dimensional materials as efficient saturable absorbers offer a new horizon in ultrafast fiber laser. However, the interactions on atomic scale between these two-dimensional materials and fiber and the fiber effect on the carrier dynamics have not been realized. To figure out the exact role of fiber and the carrier dynamics affected by the fiber substrate related to ultrafast photonics, bismuthene, a newly reported 2D quantum material used in a passive mode-locking fiber laser, deposited on α-quartz has been investigated. We surprisingly found that the α-quartz substrate can strongly accelerate the nonradiative electron-hole recombination of bismuthene in theory, and the transient absorption spectra of bismuthene on normal glass and α-quartz further verify the substrate effect on carrier dynamics of bismuthene. The discovery provides new thinking about substrate effect to regulate the performance of ultrafast mode-locking fiber lasers as well as ultrafast photonics.