High-order femtosecond vortices up to the 30th order generated from a powerful mode-locked Hermite-Gaussian laser

• Published in: Light, science & applications Vol. 12; no. 1; p. 207
• Main Authors: Liu, Hongyu, Yan, Lisong, Chen, Hongshan, Liu, Xin, Liu, Heyan, Chew, Soo Hoon, Gliserin, Alexander, Wang, Qing, Zhang, Jinwei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.08.2023; Springer Nature B.V; Nature Publishing Group
• Subjects: 639/624/1020/1090; 639/624/1020/1094; 639/624/1020/1095; Lasers; Microwaves; Optical and Electronic Materials; Optical Devices; Optics; Oscillators; Photonics; Physics; Physics and Astronomy; RF and Optical Engineering; Vortices
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-023-01241-z

Femtosecond vortex beams are of great scientific and practical interest because of their unique phase properties in both the longitudinal and transverse modes, enabling multi-dimensional quantum control of light fields. Until now, generating femtosecond vortex beams for applications that simultaneously require ultrashort pulse duration, high power, high vortex order, and a low cost and compact laser source has been very challenging due to the limitations of available generation methods. Here, we present a compact apparatus that generates powerful high-order femtosecond vortex pulses via astigmatic mode conversion from a mode-locked Hermite-Gaussian Yb:KGW laser oscillator in a hybrid scheme using both the translation-based off-axis pumping and the angle-based non-collinear pumping techniques. This hybrid scheme enables the generation of femtosecond vortices with a continuously tunable vortex order from the 1st up to the 30th order, which is the highest order obtained from any femtosecond vortex laser source based on a mode-locked oscillator. The average powers and pulse durations of all resulting vortex pulses are several hundred milliwatts and <650 fs, respectively. In particular, 424-fs 11th-order vortex pulses have been achieved with an average power of 1.6 W, several times more powerful than state-of-the-art oscillator-based femtosecond vortex sources.