60-nm-span wavelength-tunable vortex fiber laser with intracavity plasmon metasurfaces

TL;DR

This paper introduces a broadband, wavelength-tunable vortex fiber laser with intracavity plasmon metasurfaces that can generate high-quality orbital angular momentum beams across a wide wavelength range, surpassing previous limitations.

Contribution

It presents the first metasurface-assisted vortex fiber laser with continuous wavelength tunability from 1015 nm to 1075 nm, enabling flexible OAM beam generation with high efficiency.

Findings

Achieved nearly twice the wavelength tunability of previous vortex fiber lasers.

Demonstrated broadband gap-surface plasmon metasurface design for tunable OAM beams.

Extended cavity-metasurface design for higher-order and complex structured beams.

Abstract

Wavelength-tunable vortex fiber lasers that could generate beams carrying orbital angular momentum (OAM) hold great interest in large-capacity optical communications. The wavelength tunability of conventional vortex fiber lasers is however limited by the range of 35 nm due to narrow bandwidth and/or insertion loss of mode conversion components. Optical metasurfaces apart from being compact planar components can flexibly manipulate light with high efficiency in a broad wavelength range. Here, we propose and demonstrate for the first time, to the best of our knowledge, a metasurface-assisted vortex fiber laser that can directly generate OAM beams with changeable topological charges. Due to the designed broadband gap-surface plasmon metasurface, combined with an intracavity tunable filter, the laser enables OAM beam with center wavelength continuously tunable from 1015 nm to 1075 nm, nearly twice of other vortex fiber lasers ever reported. The metasurface can be designed at will to satisfy requirements for either low pump threshold or high slope efficiency of the laser. Furthermore, the cavity-metasurface configuration can be extended to generate higher-order OAM beams or more complex structured beams in different wavelength regions, which greatly broadens the possibilities for developing low-cost and high-quality structured-beam laser sources.