Related Experiment Video
Updated: Aug 30, 2025
10:52
Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
9.8K
Ultrafast beam pattern modulation by superposition of chirped optical vortex pulses
Asami Honda1, Keisaku Yamane2, Kohei Iwasa1
1Department of Applied Physics, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, 060-8628, Japan.
Scientific Reports
|September 2, 2022
Summary
This study demonstrates ultrafast beam pattern modulation using chirped optical vortex pulses, achieving stable sub-THz frequency modulations. The technique enables precise control for applications in exciting quasi-particles and collective excitations.
Area of Science:
- Physics
- Optics
- Ultrafast Science
Background:
- Pulse shaping techniques leverage space-time coupling for ultrashort and chirped pulses.
- Optical vortex (OV) pulses and spatial modes are crucial in advanced optical applications.
Purpose of the Study:
- To demonstrate ultrafast beam pattern modulation via superposition of chirped OV pulses with orthogonal spatial modes.
- To achieve stable and robust modulations at sub-terahertz frequencies with precise phase control.
Main Methods:
- Superposition of chirped optical vortex pulses with orthogonal spatial modes.
- Precise phase control in spatial and time/frequency domains.
- Analysis of Poynting vector and orbital angular momentum (OAM).
Main Results:
- Stable sub-THz frequency beam pattern modulations, including ring-shaped optical lattices (2, 4, 6 petals) and radial patterns.
- Demonstrated linear fringe modulation with chirped Gaussian pulses.
- Achieved 32% energy conversion efficiency from 360 μJ input to 115 μJ output.
Conclusions:
- The ultrafast beam pattern modulation technique is suitable for spatially coherent excitation of quasi-particles and collective charge/spin excitations.
- While ring-shaped lattices rotate at sub-THz frequencies, the net OAM is negligible, requiring careful consideration for OAM transfer applications.
