LASER (Light Amplification by Stimulated Emission of Radiation) is a device that is used for creation and amplification coherent electromagnetic radiation. Coherent radiation occurs when, in the process of creating laser radiation comes to stimulated emission of photons, then 2 photons with the same direction of propagation, same phase and polarisation are obtained. Lasers are designed so that their light source depends on the type of active medium used, so there are gas, chemical, solid-state, semiconductor, dye organic, excimer, fiber and free electron lasers. Semiconductor lasers are the most widely used of all lasers. In this final paper, in addition to the theoretical part, the practical part of the work will also be explained in the appendix, which is Morse code communication between two Arduino boards, one as a laser signal sender and the other as a laser signal receiver. The communication between the boards will be printed in the Arduino program on the computer screen.