Passively mode-locked in Er-doped fiber laser based on semi-metallic InBi saturable absorber

Two-dimensional materials have drawn great interest for their applications in mode-locking owning to their unique optical nonlinearities. However, most of these 2D materials are semi-conductor. In this study, a new kind of semimetal Indium bismuth (InBi) is reported which is a topological nodal-line semimetal with exotic physical properties. The InBi nanomaterials was prepared through liquid phase exfoliation method with average thickness of 32.8 nm. The saturable absorption property was measured and passive mode-locking operation was achieved successfully in Er-doped fiber laser. It exhibits a modulation depth of 3.21%, a saturable intensity of 100 MW/cm2, and a pulse width about 859.97 fs corresponding to the central wavelength of 1562.27 nm and 3-dB bandwidth of 2.98 nm. The experimental results open a new avenue for the use of semimetals InBi nanomaterials in lasers and photonics applications.