WS2 mode-locked ultrafast fiber laser

TLDR

Graphene‑like two‑dimensional materials such as WS₂ and MoS₂ are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications, and few‑layer WS₂ shares remarkable physical properties similar to MoS₂. Soliton mode‑locking is achieved in an erbium‑doped fiber laser using two types of WS₂‑based saturable absorbers: one fabricated by depositing WS₂ nanosheets on a D‑shaped fiber, the other synthesized by mixing WS₂ solution with polyvinyl alcohol and evaporating onto a substrate. We demonstrate that WS₂ nanosheets exhibit ultrafast nonlinear saturable absorption and a high optical damage threshold, and that at 600 mW pump power two WS₂‑based saturable absorbers can stably mode‑lock without damage, indicating that few‑layer WS₂ is a promising high‑power flexible saturable absorber for ultrafast optics with potential applications in high‑power pulsed lasers, materials processing, and frequency‑comb spectroscopy.

Abstract

Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with MoS2, few-layer WS2 has remarkable physical properties. Here, we demonstrate for the first time that WS2 nanosheets exhibit ultrafast nonlinear saturable absorption property and high optical damage threshold. Soliton mode-locking operations are achieved separately in an erbium-doped fiber laser using two types of WS2-based saturable absorbers, one of which is fabricated by depositing WS2 nanosheets on a D-shaped fiber, while the other is synthesized by mixing WS2 solution with polyvinyl alcohol and then evaporating them on a substrate. At the maximum pump power of 600 mW, two saturable absorbers can work stably at mode-locking state without damage, indicating that few-layer WS2 is a promising high-power flexible saturable absorber for ultrafast optics. Numerous applications may benefit from the ultrafast nonlinear features of WS2 nanosheets, such as high-power pulsed laser, materials processing and frequency comb spectroscopy.