Mode-locked erbium-doped fiber laser based on a mechanically exfoliated ReS2 saturable absorber onto D-shaped optical fiber

Abstract

In this work, we report a femtosecond mode-locking Erbium-doped fiber laser using mechanically exfoliated rhenium disulfide (ReS2) deposited onto the polished surface of a D-shaped optical fiber. By performing the polarization and saturable absorption measurements, the sample exhibited a polarization extinction ratio of 10 dB (90%) and nonlinear transmittance variation of 3.40%. When incorporated into the cavity as a saturable absorber (SA), the passive mode-locking performance of 220 fs was achieved. This is the best mode-locking performance ever reported in literature achieved with all-fiber based ReS2 SA. By using density functional theory (DFT) calculations, we obtained the electronic states and the optical absorption spectrum at 1550 nm attributed by defects in the ReS2 structures, which is consistent with its linear and nonlinear optical absorption in the laser mode-locking mechanism.