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Time-varying orbital angular momentum in tight focusing of ultrafast pulses

Authors :
Zhangyu Zhou
Changjun Min
Haixiang Ma
Yuquan Zhang
Xi Xie
Hao Zhan
Xiaocong Yuan
Source :
Optics Express. 30:13416
Publication Year :
2022
Publisher :
Optica Publishing Group, 2022.

Abstract

The orbital angular momentum (OAM) of light has important applications in a variety of fields, including optical communication, quantum information, super-resolution microscopic imaging, particle trapping, and others. However, the temporal properties of OAM in ultrafast pulses and in the evolution process of spin-orbit coupling has yet to be revealed. In this work, we theoretically studied the spatiotemporal property of time-varying OAM in the tightly focused field of ultrafast light pulses. The focusing of an incident light pulse composed of two time-delayed femtosecond sub-pulses with the same OAM but orthogonal spin states is investigated, and the ultrafast dynamics of OAM variation during the focusing process driven by the spin-orbit coupling is visualized. Temporal properties of three typical examples, including formation, increase, and transformation of topological charge are investigated to reveal the non-uniform evolutions of phase singularities, local topological charges, self-torques, and time-varying OAM per photon. This work could deepen the understanding of spin-orbit coupling in time domain and promote many promising applications such as ultrafast OAM modulation, laser micromachining, high harmonic generation, and manipulation of molecules and nanostructures.

Details

ISSN :
10944087
Volume :
30
Database :
OpenAIRE
Journal :
Optics Express
Accession number :
edsair.doi.dedup.....07343cf8e26b2b865e67b21aeb91c28a