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Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing
Published on: April 25, 2019
Femtosecond laser filament array generated with step phase plate in air
Hui Gao1, Wei Chu, Guoliang Yu
1Institute of Modern Optics, Nankai University, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Tianjin 300071, China.
Optics Express
|March 14, 2013
Summary
Researchers generated femtosecond laser filament arrays using novel step phase plates. These plates, including semicircular, quarter-circle, and eight-octant designs, precisely control filament number and spatial arrangement.
Area of Science:
- Nonlinear Optics
- Laser Physics
- Plasma Physics
Background:
- Femtosecond laser filaments are intense self-guided light channels formed through nonlinear propagation in air.
- Generating controlled filament arrays is crucial for applications like laser-induced plasma channels and atmospheric modification.
- Previous methods for generating filament arrays often lack precise control over filament number and spatial distribution.
Purpose of the Study:
- To demonstrate a novel method for generating femtosecond laser filament arrays in air.
- To investigate the influence of step phase plate geometry on filament array characteristics.
- To explore the potential for creating ring-shaped filament arrays and elongating filament lengths.
Main Methods:
- Utilized three types of step phase plates with a π phase lag: semicircular phase plate (SCPP), quarter-circle phase plate (QCPP), and eight-octant phase plate (EOPP).
- Performed experimental generation of filament arrays in air.
- Conducted numerical simulations to analyze filament formation and transverse patterns.
- Investigated the effect of lens focal length on filament separation distances.
- Proposed the use of an axicon for generating ring-shaped filament arrays.
Main Results:
- Successfully generated filament arrays consisting of two, four, and eight filaments using SCPP, QCPP, and EOPP, respectively.
- Demonstrated that the transverse patterns of the filament arrays are directly determined by the geometrical shapes of the phase plates.
- Observed that filament separation distances vary with the focal lengths of the employed lenses.
- Showcased the potential to create ring-shaped filament arrays with significantly elongated filament lengths using an axicon.
Conclusions:
- Step phase plates with π phase lag offer a realistic and controllable method for generating femtosecond laser filament arrays.
- The geometry of the phase plate dictates the number and transverse arrangement of the filaments.
- This technique provides a versatile platform for creating tailored filament structures for various scientific and technological applications.
