This bachelor thesis presents the principle of making optical serial communication with a laser performed using an Arduino microcontroller. Communication takes place using two Arduino Uno boards and works by first entering the message you want to send and then the received message is displayed on the connected screen or monitor. The communication is digital, where turned on laser represents a logical ‘1’ and the switched off a logical ‘0’ where each Arduino has a defined table showing the binary values of each character that can be received or sent (number, letter, sign). A laser was chosen as the light source, which aims to show the working principle of optical communication, which is the foundation of today's Internet infrastructure, and for its work, unlike our red laser, it uses infrared light. For simplicity, air was chosen as the medium in which the laser light is transmitted, but the use of optical fiber in the same configuration would yield far better working and allow us to use this type of communication outside the visual circle of laser because the optical thread can bend. A light beam presence detector is a photoresistor that changes its internal resistance depending on external light, and this change can be measured and decoded by another Arduino to receive the received message.