Ultrafast nonlinear optical properties of MTe2 (M = V and Ta) and their application as broadband saturable absorbers

Abstract

Two-dimensional transition-metal dichalcogenides, specifically MTe₂ (M = V and Ta), have recently inspired significant interest due to their unique electronic properties. However, their ultrafast nonlinear optical properties have not been extensively studied for use in ultrafast photonics applications. In this study, MTe₂ (M = V and Ta) nanosheets were prepared using the liquid-phase exfoliation technique, and their bandgaps were calculated using density functional theory. The results show that both materials exhibit zero bandgaps, indicating that they are suitable for broadband photonic applications. The nonlinear absorptions of VTe₂ and TaTe₂ were characterized at 1.5 μm, with saturation intensities of 0.61 MW cm⁻² and 1.36 MW cm⁻², and modulation depths of 2.30% and 2.55%, respectively. By using the two fabricated materials as saturable absorbers, highly-stable passively mode-locked Er-doped fiber lasers were achieved for the first time, with pulse durations of 494 and 773 fs. Our experimental findings not only demonstrate the potential of MTe₂ (M = V and Ta) in ultrafast photonics applications, but also advance photonic and optoelectronic applications.