Wavelength-Tunable and OAM-Switchable Ultrafast Fiber Laser Enabled by Intracavity Polarization Control

Ultrafast laser that directly emits vortex beam has broad application prospects in many research fields and applications, such as telecommunication, bio-sampling and quantum information science. In this article, we demonstrate a wavelength-tunable and OAM-switchable ultrafast fiber laser enabled by intracavity polarization controlling elements. The mode-locked laser can emit vortex beam outputs with a topological charge of l = +1 or l = −1 and the center wavelength can be continuously tuned from 1015 nm to 1038nm. The obtained output pulse has a pulse energy of 3.3 nJ and a compressed pulse duration of 87 fs. Compared with previous results, this laser can emit OAM-switchable output with a shorter pulse duration and a broad wavelength tuning range. The concept of adding polarization control elements to a mode-locked fiber laser can be further expanded to build laser with more sophisticated and customizable outputs.