Spiral spectrum of anomalous vortex beams propagating in a weakly turbulent atmosphere

ABSTRACT

We study the spiral spectrum of anomalous vortex beams propagating through a turbulent atmosphere. Based on the Huygens–Fresnel integral and the Rytov approximation, the integral expression and then the analytical expression for the spiral spectrum of anomalous vortex beams in the weakly turbulent atmosphere are derived. The capacity of wireless optical links using the anomalous vortex beam is obtained. It is found that the spiral spectrum of the anomalous vortex beam is less affected by turbulence than that of the Laguerre-Gaussian beam. And thus, the information capacity of wireless optical links using the anomalous vortex beam is larger than that using the Laguerre-Gaussian beam. The influence of beam order, wavelength, topological charge, propagation distance, refractive index structure constant and the radius of receiver aperture on spiral spectrum is investigated. These results contribute to reduce the disturbing effects of atmospheric turbulence on the orbital angular momentum of the vortex beam.

KEYWORDS:

• Anomalous vortex beam
• spiral spectrum
• atmospheric turbulence
• Laguerre–Gaussian beam
• capacity

PACS:

• 42.25.Dd
• 42.68.Bz

Acknowledgments

This work is supported by the National Natural Science Foundation of China (grant number 41801229), the Science and Technology Plan of Beijing Municipal Education Commission (Grant nos. KM20181001600117 and KM 201710016008) and Zhejiang Provincial Natural Science Foundation of China (grant number LQ19F010008).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China: [Grant Number 41801229]; the Science and Technology Plan of Beijing Municipal Education Commission: [Grant Number KM20181001600117 and KM 201710016008]; Zhejiang Provincial Natural Science Foundation of China: [Grant Number LQ19F010008].