Wavelength-Tunable and OAM-Switchable Ultrafast Fiber Laser Enabled by Intracavity Polarization Control
Haifeng Hu, Zhuo Chen, Qian Cao, Qiwen Zhan
Abstract
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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> = +1 or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l</i> = −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.