Free space optics (FSO) is a competent technology for wireless communication providing solutions to bandwidth, cost, and portability challenges in radio frequency communication. This paper presents a numerical approach for securing information in free space by using chaos produced through semiconductor lasers. Laser rate equations are applied to model chaos generated by semiconductor laser, followed by chaos masking scheme to hide the message signal inside the generated chaos before transmission. As FSO communication link availability and efficiency is a major concern in different atmospheric conditions, therefore fog, rain, and haze conditions are analyzed and compared for FSO communication‐based on Q‐factor and eye diagram patterns. The results are further studied for both FSO communication models, ie, with and without applying chaos masking scheme.