60 nm Span Wavelength-Tunable Vortex Fiber Laser with Intracavity Plasmon Metasurfaces

Abstract

Wavelength-tunable vortex fiber lasers that could generate beams carrying orbital angular momentum (OAM) hold great attention in large-capacity optical communications. The wavelength tunability of conventional vortex fiber lasers is, however, limited by a 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 customizable topological charges. Due to the designed broadband gap-surface plasmon metasurface, combined with an intracavity tunable filter, the laser enables an OAM beam with a center wavelength continuously tunable from 1015 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.

High Efficiency Triple-Helix Solenoid Beam Generated by Dielectric Metasurface

“…We next show that an interferometric method can yield further information about the solenoid beam, revealing the OAM values of the components. Evaluating OAM values typically requires interference setups that display specific spiral or forked patterns. − While many studies have outlined methods for measuring the characteristics of single-component vortex beams, there is a limited exploration into OAM within more complex beams.…”

Intracavity spatiotemporal metasurfaces

“…Recent work indicates that the incorporation of metasurface in a solid-state or fiber laser cavity may enable coherent light emission with tailored spatial mode profile, such as vortex laser beam carrying orbital angular momentum (OAM), in a compact form factor. [15][16][17] The integration of metasurface into a laser cavity may pave the way for the development of the next generation of miniaturized laser sources with a tailorable structured light field. 18 However, despite their versatility to spatially manipulate the light field, most metasurfaces only possess a time-invariant response postfabrication.…”

Tunable Three-Wavelength Fiber Laser and Transient Switching between Three-Wavelength Soliton and Q-Switched Mode-Locked States

“…Ultrafast fiber lasers [1][2][3] have potential applications in optical communication, [4] optical sensing, [5] and nonlinear science. [6] Wavelength-tunable [7][8][9] fiber lasers and multiwavelength [10][11][12] fiber lasers, as the main types of ultrafast fiber lasers, are widely used due to their unique spectral characteristics. Recently, an ultra-wideband (1700 nm-1900 nm) tunable thulium-doped fiber laser [13] achieved dissipative soliton output in the 200 nm range.…”