Wavelength Tunable Pulsed Lasers Enabled by a Versatile Metafiber Functioning as Both Saturable Absorber and Filter.

Wavelength-tunable pulsed lasers have garnered significant research interest due to their critical role in applications requiring precise spectral matching, such as wavelength-division multiplexing and spectroscopic analysis. Although recent hybrid architectures integrating saturable absorbers with wavelength-selective components have enabled notable progress, these systems remain constrained by two fundamental challenges: excessive coupling losses and complex alignment procedures. Here, a compact wavelength-tunable pulsed laser configuration is presented that employs a monolithic fiber-based component, effectively addressing the complexity and alignment issues inherent in conventional hybrid systems. By leveraging advanced manufacturing techniques, a 2D metafiber is integrated with a 3D Fabry-Perot interferometer at the end facet of a single-mode optical fiber, forming a metafiber Fabry-Perot structure that simultaneously functions as both a saturable absorber and a tunable optical filter. Exploiting the versatile optical feedback provided by the Fabry-Perot cavity, our design achieves Q-switching operation in the telecommunication band and enables approximately 10 nm dynamic wavelength tuning through temperature/refractive index modulation. This work circumvents the structural complexity of traditional hybrid systems while ensuring stable laser operation, demonstrating a promising pathway for high-performance wavelength-tunable pulsed laser applications.