Polarization-Controlled Wavelength-Tunable Pulsed Laser Based on Metafiber.

Wavelength-tunable pulsed lasers have the ability to flexibly adjust laser energy and wavelength according to the properties of different materials platforms and experimental requirements, thereby markedly enhancing efficiency and precision. Thus, wavelength-tunable pulsed lasers have attracted significant attention in fields such as wavelength division multiplexing, precision material processing, and spectroscopic analysis. Here, a polarization-sensitive Au-nanorod metasurface has been proposed that integrates saturable absorption with wavelength-tuning capabilities. By fabricating this metasurface structure on the facet of the fiber, known as a metafiber, low-loss coupling between the metasurface and the fiber laser system is achieved. In experiments, we have successfully demonstrated Q-switched pulse, achieving precise control over pulse width (13.5-29.8 μs), repetition rate (15.3-43.7 kHz), and pulse energy (15.2-30.7 nJ) through meticulous adjustment of the pump power. Notably, by modulating the input polarization state, the response wavelength of the metafiber can be effectively controlled, enabling wavelength-tunable pulsed laser output within a 5-nm range. This achievement introduces a new concept and provides a viable solution for the design and development of next-generation compact, high-efficiency, and multifunctional laser systems.