Abstract

This article presents ion irradiation as a unique technique for tailoring the optical properties of the semiconducting tungsten disulfide (WS₂) by creating S vacancies in the system and thus controlling material stoichiometry. It is experimentally demonstrated that the S-vacancies can be created in a controllable density in the WS₂ monolayer by argon ion irradiation. First-principles calculations reveal that the S-vacancies produce intermediate states in the band gap, which determines the near-infrared optical absorption of the WS₂ monolayer. Increasing the density of the S-vacancies, the enhanced near-infrared linear and saturable absorption of WS₂ are observed in experiments and explained by the results of first-principles calculations. Utilizing the irradiated WS₂ as the saturable absorber in a waveguide laser, the passively Q-switched pulsed waveguide laser operation has been optimized, demonstrating a promising WS₂ application as a saturable absorber, and opening new avenues to tailor the optical response of TMDCs.

© 2017 Optical Society of America