# Simultaneous Lightwave and Power Transfer for Internet of Things Devices
## 1 Introduction  
Simultaneous lightwave and information transfer (SLIPT) has seen tremendous progress over the last few years. SLIPT is the optical equivalent of the widely studied simultaneous wireless information and power transfer (SWIPT) using radio frequency (RF) signals used for communication to harvest energy [1, 2]. SWIPT can be subject to low conversion efficiency and complicated system design. Compared to SWIPT, SLIPT also has fewer challenges in terms of licensing and allowable electromagnetic field radiation, restricted by maximum RF exposure [3]. SLIPT can co-exist with optical wireless communication (OWC) in the visible and infrared bands, better known as visible light communication (VLC) and free space optics (FSO). Several demonstrations reported in the literature have shown the feasibility of SLIPT in indoor and outdoor media. SLIPT is also useful for underwater wireless optical communication (UWOC) applications.  
A seminal paper by [PERSON] and [PERSON] reported the reception of 3-kbps signals emitted by a light-emitting diode (LED) using a solar cell (SC) placed 40 cm from the transmitter while harvesting solar energy [4]. Authors of [5] proposed the design of a silicon (Si) SC-based receiver that was able to decode signals modulated using an orthogonal frequency-division multiplexing (OFDM) scheme at a data rate of 11.84 Mbps. The authors also reported receiving optical signals with an amplitude of \(0.7\times 10^{-3}\) W/cm\({}^{2}\)[5]. An 8-mm\({}^{2}\) organic SC was used to establish a 34.2-Mbps OFDM-based communication link while generating a 0.2-mW power [6]. A 500-Mbps data rate was achieved over a 2-m free space OFDM-based link using a circular Gallium Arsenide (GaAs) SC illuminated by a near-infrared beam emitted by an 847-nm laser [7]. The used GaAs SC has a diameter of 1 mm and a 3-dB bandwidth of 24.5 MHz. A follow-up study using the same SC reported a data rate of 743 Mbps and harvested 1.3 mW of power [8]. A 1-Gbps record data rate was achieved in [9] using the same 0.8-mm\({}^{2}\) GaAs SC used in [7, 8]. In addition to the small active area of the SC, a key element for reaching such data rates in [8, 9] was the use of an alternatingcurrent-direct current (AC-DC) decoupling receiver initially used in [5]. A perovskite SC was used to achieve a 56-Mbps data rate and 20% power conversion under white light LED illumination [10].  
We previously proposed the design of a low-cost internet of underwater things (IoUT) device that can harvest energy and received information using a silicon SC. The designed IoUT device contained a temperature sensor and a camera used to stream a video with an integrated laser diode [11]. The potential of SLIPT in underwater media was further highlighted in [12].  
Additionally to VLC and UWOC systems, the concept of simultaneous information decoding (ID) and energy harvesting (EH) is seen as a potential solution to coping with the connectivity divide affecting those rural places with low Internet penetration by using already existing photovoltaic panels to receive optical signals while also harvesting solar energy [13; 14]. Indeed, a real-world demonstration reported the detection of signals emitted from a distance of 30 m at a data rate of 8 Mbps using a commercially available solar panel that could also harvest 5 W of power from sunlight [14]. We recently demonstrated a self-powered weather station for rural areas and difficult access locations [15]. The designed system was able to decode OOK-modulated data signals received by the SC. The system operated autonomously without any user intervention over a period of one week [15].  
In this work, we present a SLIPT-based prototype used to harvest energy from various sources and decode OFDM-modulated signals with different data rates received by a large-area silicon SC. A net data rate of 1.3 Mbps is demonstrated. The designed self-powered device is connected to an IR motion sensor, which is tested to detect the movements of unmanned aerial vehicles (UAVs).