Phuchortham, SabaiSabit, Hakilo2026-05-082026-05-082026-04-26Photonics, ISSN: 2304-6732 (Print); 2304-6732 (Online), MDPI AG, 13(5), 425-425. doi: 10.3390/photonics130504252304-67322304-6732http://hdl.handle.net/10292/21047<jats:p>Free-space optical (FSO) communication is an attractive high-capacity wireless technology for terrestrial, aerial, and satellite links. However, FSO performance is strongly affected by multiple impairments, including path loss, turbulence attenuation, pointing errors, and equipment loss. Therefore, accurate performance evaluation requires channel modelling that accounts for both deterministic power losses and stochastic channel effects. This paper presents a comprehensive and structured review of FSO channel modelling, covering the transmission, propagation medium, and receiver sections. The composite channel response is represented using a mathematical formulation. Commonly used FSO models are reviewed and organised, including Beer–Lambert and geometrical loss, Kim and Kruse path loss models, Lognormal, Gamma–Gamma, K, and Málaga distributions, along with pointing-error and angle-of-arrival models. Each model is explained in terms of its physical meaning, assumptions, and applicable operating conditions. Lastly, a numerical example is presented to demonstrate how deterministic losses and stochastic channel effects can be combined in FSO performance evaluation.</jats:p>Copyright: © 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.https://creativecommons.org/licenses/by/4.0/5102 Atomic, molecular and optical physicsoptical wireless communicationsfree-space optical communicationpath lossatmospheric turbulencepointing errorswireless channelJournal ArticleOpenAccess10.3390/photonics13050425