Toward defeating diffraction and randomness for laser beam propagation in turbulent atmosphere

TL;DR

This paper investigates laser beam propagation through turbulent atmosphere, revealing that intense speckles can be used to enhance power delivery by timing laser pulses during optimal atmospheric conditions, surpassing diffraction limits.

Contribution

It introduces a method to exploit intense speckles formed in turbulent atmosphere for improved laser power delivery by timing pulses during optimal realizations.

Findings

Intense speckles preserve Gaussian shape and diameter.

Optimal realizations occur in 1/1000 atmospheric cases.

Power at speckles exceeds diffraction-limited and average intensities.

Abstract

A large distance propagation in turbulent atmosphere results in disintegration of laser beam into speckles. We find that the most intense speckle approximately preserves both the Gaussian shape and the diameter of the initial collimated beam while loosing energy during propagation. One per 1000 of atmospheric realizations produces at 7km distance an intense speckle above 20\% of the initial power. Such optimal realizations create effective extended lenses focusing the intense speckle beyond the diffraction limit of vacuum propagation. Atmospheric realizations change every several milliseconds. We propose to use intense speckles to greatly increase the time-averaged power delivery to the target plane by triggering the pulsed laser operations only at times of optimal realizations. Resulting power delivery and laser irradiance at the intense speckles well exceeds both intensity of diffraction-limited beam and intensity averaged over typical realizations.