## 1 Introduction  
Free-space optical (FSO) systems, a promising technology for the future sixth-generation (6G) wireless communication systems, possess attractive inherent advantages including ultra-high data rates, low cost, and ease of installation [1]. However, the performance of an FSO system is degraded due to its sensitivity to weather conditions, atmospheric turbulence-induced fading, and the effect of pointing errors, which is a result of the misalignment that occurs between the optical transmitter and the receiving aperture [2]. Statistical distributions, such as the Malaga distribution, have been developed to accurately model the effects of atmospheric turbulence and pointing errors [3]. The adverse effects of weather conditions, atmospheric turbulence, and pointing errors on the performance of FSO systems can be combated by deploying a relay between the transmitter and the receiver [4]. Relaying techniques also extend the transmission coverage and mitigate the short range issue of FSO systems [5]. Relaying can be implemented as FSO/FSO systems where all hops between the source and the destination are FSO links [6]. Additionally, mixed FSO/radio frequency (RF) systems can also be implemented [7] where one of the hops will operate as an RF link. Relay-assisted FSO systems are well studied in the literature (please refer to [8] and the references cited therein.). For instance, the study in [9] provides average bit error rate (BER), outage probability (OP), and ergodic capacity expressions of a dual-hop (DH) FSO/FSO fixed-gain relaying system over a Gamma-Gamma turbulence channel with pointing errors. Further, the work in [10] presents average BER and OP expressions of a multi-hop FSO system with an amplify-and-forward (AF) relaying technique over a double-generalized Gamma turbulence channel with pointing errors. Also, the study in [11] derives average BER, OP, and ergodic capacity expressions of a DH FSO/FSO system with a decode-and-forward (DF) relaying technique over a Malaga turbulence channel with pointing errors. In relay-assisted FSO systems, the optical signal received at the relay is composed of an alternating current (AC) component that carries the information and a direct current (DC) component that guarantees the non-negativity of the optical signal [12]. Recently, the simultaneous lightwave information and power transfer (SLIPT) concept has been introduced, where the relay can harvest energy from the received optical signal by extracting its DC component and use it as a transmit power [13]. By adopting SLIPT, the received optical signal is not just utilized for information reception, but also for energy harvesting (EH) to wirelessly deliver energy to the relay. EH, which minimizes frequent battery replacements and material waste, plays a crucial role in fulfilling the sustainability goals of 6G networks [14]. Proof-of-concept experiments regarding optical energy harvesting have been presented in [15; 16]. Studies regarding the performance of SLIPT-based FSO systems are still scarce in the literature [17]. In [18], OP expression of a SLIPT-based AF FSO/RF system is provided. Also, the work in [19] derives OP, average BER, and ergodic capacity expressions of a SLIPT-based mixed DF FSO/RF system. Furthermore, the study in [20] presents OP, coverage probability, and throughput expressions of a SLIPT-based FSO/RF system with a non-orthogonal multiple access technique. It should also be noted that SLIPT is proposed for indoor [21; 22] and underwater [23; 24] wireless optical communication systems. Physical layer security [25] addresses the confidentiality of the wirelessly transmitted information without utilizing any encryption techniques in the upper layer of the network stack [26]. Although FSO systems are more secure than their RF counterparts [27], FSO links are also susceptible to eavesdropping due to the atmospheric turbulence, pointing errors, and the nature of the optical beam divergence [28]. Physical layer security for FSO communication systems is fairly studied in the literature [29].