Design and Experimental Analysis of a Laser-Based Li-Fi Communication System

Abstract

Light Fidelity (Li-Fi) is an emerging optical wireless communication (owc) system that employ light-emitting diodes (LEDs) to acheive medium to high speed transmission using optical signals. Li Fi is a form of Visible light communication(VLC) technology i.e. lifi provides secure communication connectivity for under water communication,smart home, smart cities, classrooms and hospital,medicial equipment,traffic and vehicle communication. It strengthens security compared to modern radio-frequency (RF) communication systems. RF-based systems are sensitive to jamming, and the available spectrum is heavily occupied due to multiple devices operating on the same frequency band. This results in issues such as low data quality, collisions, and interference, particularly in indoor environments.In this work, a low-cost Li-Fi communication system is implemented to address these limitations while keeping the system affordable and simple. The proposed approach uses microcontrollers such as ESP8266 and ESP32 as the transmitter and receiver, respectively. At the transmitter side, text data are entered from a phone or laptop into the ESP8266 through a serial interface and transmitted using a laser diode.The laser diode is controlled via On-Off Keying (OOK) modulation, in which the light source alternates between ON and OFF states to represent binary data. By streamlining the encoding and decoding process, this method facilitates the receiver’s detection and interpretation of the transmitted text. At the receiver side, an ESP32 microcontroller is used to handle the received data, process it, and display the decoded text on an OLED screen. A high-sensitivity light dependent resistor (LDR) sensor module is used to sense the incoming light signal in real time, and threshold-based detection is applied to distinguish between logic levels. The system was tested indoors under normal lighting conditions, and successful text transmission was observed without noticeable interference during communication. The experimental result of Li-Fi demonstrate the high speed data transmission upto 100 Gbps.

Introduction

Light Fidelity (Li-Fi) is an emerging wireless communication technology that uses light instead of radio frequency (RF) to transmit data. It offers advantages such as high data rates, improved security, and reduced electromagnetic interference, making it suitable for environments where RF communication is limited or sensitive. The study proposes a low-cost optical communication system that uses a laser diode for transmission and an LDR sensor for reception, along with microcontrollers like ESP8266 microcontroller and ESP32 microcontroller.

The system works using On-Off Keying (OOK) modulation, where binary data is transmitted by turning the laser ON for “1” and OFF for “0”. The transmitter converts text data into optical signals using the ESP8266, and the receiver uses an LDR sensor to detect changes in light intensity. A threshold-based decision mechanism helps the system distinguish between valid signals and background lighting, improving reliability in indoor environments.

The methodology involves encoding text data, transmitting it through a laser beam, detecting the signal with the LDR sensor, and decoding it using the ESP32 microcontroller. The decoded message is displayed on an OLED screen. System performance was evaluated using Bit Error Rate (BER) to measure transmission accuracy at different distances.

Experiments were conducted in indoor lighting conditions to test real-world performance. Results showed stable and accurate data transmission at short distances, while performance decreased as distance increased due to signal attenuation, alignment issues, and background light interference. The system achieved low BER and reliable communication at shorter ranges, but accuracy reduced beyond longer distances because the LDR sensor has limited response speed.

Conclusion

The work of the research concludes the design and testing of a laser-based optical network for short range text data communication. The experimental results demonstrated that the proposed system was capable of performing optical data transmission under indoor lighting conditions. Using on–off keying modulation and adaptive threshold-based reception, the system was operated. The results of the trials verify that it is feasible to transmit text reliably at short distances if the alignment between the transmitter and receiver is properly maintained. The laser diode used to supply the light provided high directionality, which facilitated focused signal transmission, and the adaptive threshold method allowed detection to be more stable even in the presence of ambient lighting. The use of high-speed photodiodes and optical lenses can significantly increase the distance over which transmission can take place with a higher degree of reliability. The use of an LDR sensor results in a slow response; thus, the achievable data rate is limited. In addition, the need for strict lineof-sight alignment reduces the degree of freedom and the communication range. These disadvantages highlight a tradeoff between system simplicity and performance. Despite these limitations, the present work convincingly demonstrates the operation of Li-Fi using very cheap and readily available components. The system can be considered a proof of principle optical wireless communication setup, which sets the scene for the use of faster optical sensors and higher data rates or audio transmission in the future[14].

References

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Copyright

Copyright © 2026 Ms. Tanmeet Kaur, Ayush Tripathi, Aditi Raj, Prateek Joshi, Md. Faisal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.