Atmospheric propagation of femtosecond optical pulses: Gaussian beamlet model of coherence effects

Wayne H. Knox; Alex LeBon; Taz Colangelo; Brian Gregory; Tom Chaffee

doi:10.1117/12.2676888

3 October 2023 Atmospheric propagation of femtosecond optical pulses: Gaussian beamlet model of coherence effects

Wayne H. Knox, Alex LeBon, Taz Colangelo, Brian Gregory, Tom Chaffee

Proceedings Volume 12691, Laser Communication and Propagation through the Atmosphere and Oceans XII; 126910N (2023) https://doi.org/10.1117/12.2676888
Event: SPIE Optical Engineering + Applications, 2023, San Diego, California, United States

Abstract

We consider the difficult problem of ground-based propagation of 90 femtosecond laser pulses through the turbulent atmosphere in the range of 1 mile, where the atmospheric properties change significantly according to weather conditions. Our experimental data indicates that use of femtosecond laser pulses for optical communications at up to 1.35 Gb/sec is significantly advantageous compared to CW lasers, offering much reduced error rates and higher consistency in transmission in diverse atmospheric conditions. We develop a new model using Gaussian beamlets to simulate the effects of propagation in different refractive index conditions within the beam. The results are quite consistent with the experimental observations indicating significantly less scintillation and small- scale fluctuations in received data when fs laser pulses at 1540 nm are used. In the new model, we simulate the transmitter as a coherent sum of Gaussian beamlets (5-500) and propagate them with slightly different index of refraction, corresponding to the normal variations in average index of refraction due to changing atmospheric conditions. For instance, when transmitting over one mile of air, a temperature difference within the beam of only 0.02 °C causes the Gaussian beamlets to arrive at the receiver with time delays differing by about 200 fs, exceeding the coherence time of the 90 fs laser pulses, thereby causing incoherent summation at the detector.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Wayne H. Knox, Alex LeBon, Taz Colangelo, Brian Gregory, and Tom Chaffee "Atmospheric propagation of femtosecond optical pulses: Gaussian beamlet model of coherence effects", Proc. SPIE 12691, Laser Communication and Propagation through the Atmosphere and Oceans XII, 126910N (3 October 2023); https://doi.org/10.1117/12.2676888

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available