Performance Analysis of SDM, WDM, and PDM Techniques in High-Capacity FSO Systems Under Diverse Atmospheric Conditions. - Hemanth Jaisankar; Lokeswaran Kameswaran; K. l. Syam Rajha sSundar; Tangudu Ramji; Vinoth Babu Kumaravelu; Poongundran Selvaprabhu (Int. J. Commun. Syst., 2026)