TiO2-embedded, exfoliated layers of phosphorus-doped carbon nanodot for tunable optical limiting

The coupling of TiO 2 and phosphorus-doped carbon nanodot and their effective optical limiting applications are explored in the current study. The Z-scan technique is used for probing the characteristic optical limiting properties of the hybrid. It's interesting to point out that the optical limiting value of the P-CND/TiO 2 hybrid in its crystalline phase (C-TiO 2 ) displays a lower limiting threshold value (1.98 × 10 12 Wm −2 ) than that of TiO 2 alone (2.24 × 10 12 Wm −2 ). The morphology of hybrids, such as the distribution of TiO 2 nanoparticles on the exfoliated layers of P-CND (FE-SEM), and the characteristic bonding, Ti–O–C, of the hybrid (FT-IR), point out that there exists a synergistic coupling between the TiO 2 nanoparticle and P-CND. The π-conjugated electrons and higher optical density facilitate electron/energy transfer in the hybrid. This apparently enhances the nonlinear optical absorption in C-TiO 2 . Compared to crystalline phase, TiO 2 in the amorphous phase shows substantially lower optical limiting threshold value (1.08 × 10 12 Wm −2 ). This is due to the enhanced oscillation strength induced by the localised excitonic interaction. Conversely, the hybrid in the amorphous phase lowers the nonlinear optical absorption value. The results of hybrids in both crystalline and amorphous phases indicated the optical limiting tunability of the materials. This suggests the use of materials in applications such as fibre optic communication, Q-switching, laser light shielding, etc.