JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS Vol. 21, No. 7-8, July – August 2019, p. 459 - 469 Data transmission prototypes through wireless optical communication link using Arduino microcontroller TAREK A. ELDALLAL a,b,* , HEBA A. FAYED a,b , MOUSTAFA H. ALY a,b,c a Electronics and Communications Engineering Department, College of Engineering and Technology, b Arab Academy for Science, Technology and Maritime Transport, Alexandria, Egypt c OSA member, mosaly@aast.edu In this paper, Free Space Optical communication link prototypes have been practically experimented. Audio and text data transmission models are implemented using a programmed microcontroller “Arduino Uno”. Using a 650 nm laser source, a digital audio signal is transmitted with a data rate of 506.3 kbps in addition to a text data transmitted with a bit rate of 125 kbps. Both signals are received using a TSL250R photodiode. These prototypes create an FSO communication link designed for audio and text transmission. The use of Arduino microcontroller offers a more accurate transmission of higher quality. The concept discussed can be generalized for real optical communication systems instead of lab work only. (Received December 11, 2018; accepted August 20, 2019) Keywords: Optical communication, Wireless communication, Free space optics, Data transmission, Audio signal, Text data, Arduino microcontroller 1. Introduction The use of wireless optical communication (WOC) technology has extensively increased as an alternative to the existing radio frequency (RF) technology for many applications [1]. Free space optics (FSO) is a telecommunication technology that transmits data via the atmosphere using light signal as a carrier. This technology does not require a license to use and it is capable of handling high data rates with lower power consumption and low-cost deployment. In addition, it does not suffer any interference from electronic systems and has an excellent security system where any interception can be immediately detected [2]. WOC can be performed in the infrared, the visible light, and the ultraviolet spectrums [3]. The first experiment in FSO included demonstrations conducted by Alexander Graham Bell in the late 19 th century. Bell used light beams to transmit voice conversations through air, and he called it the Photophone [4]. The technology of Bell’s photophone was not able to guarantee the required quality of service at that time, however it is considered the first practical manifestation of the free-space optical link [4]. In the last few years, there were various experiments testing the transmission of data through the wireless optical links, for both indoor and outdoor applications. Recently, after the use of microcontrollers rather than electronic circuits only, similar experiments were implemented for the same purpose and more. Researchers continued developing systems that not only transmit audio but also text, images, and videos [5], as well as providing internet access [6]. Optical wireless systems can be broadly classified as outdoor and indoor systems. The outdoor systems are also known as FSO systems. FSO links are point-to-point systems that transmit a modulated beam of visible or infrared light through the atmosphere. For a long distance, laser is used as a light source. Light Fidelity (Li-Fi) is a category of WOC that includes both infrared and visible light communications. Uniquely, Li-Fi can use the same light energy of illumination for communication. Li-Fi technology is essential for indoor applications. Light emitting diode (LED) can be switched on and off very fast that the human eye cannot detect as its operating speed is less than one microsecond. This invisible on-off activity enables data transmission using binary codes. If the LED is on, a digital ‘1’ is transmitted, and a digital ‘0’ is transmitted when the LED is off. Li -Fi allows data transmission by modulating light intensity, which is then received by a photo-sensitive detector. The light signal is then demodulated into its electronic form. In this paper, two prototypes are implemented to study and attain the concept of transmitting and receiving both audio and text data using the FSO link with the aid of an Arduino microcontroller for outdoor applications. The use of the microcontroller offers a more accurate transmission of higher quality. Each prototype is designed to transmit different types of data from the main building to other buildings on the campus representing a direct communication link between various faculty members. This connection can be generalized to include an indoor design using the Li-Fi technology by applying some manageable adjustments to achieve an internal communication between the dean and his students. The experiments, in this paper, represent a practical demonstration of FSO application according to the courses studied in the students’ undergraduate level, including optical communications and optical devices.