Oceans are one of the most challenging environments on the earth, it is not only a home for nearly a million species but also the home for many military submarines and deep-waterResearch vehicles. The oceans have been classified into 5 different zones namely the sunlight zone, the twilight zone, the Midnight Zone, the Abyssal Zone and the Hadalpelagic Zone. The proposed project focuses on the Indian ocean’s twilight zone by transmitting International Morse code through On-Off Keying (OOK) using a 650nm semiconductor laser that is operated in pulse mode to transmit pulses. Since the longer wavelengths are absent in the deep waters, the information transmitted is visibly invisible. A photo-transistor-basedreceiver estimates the values by measuring the time interval between the pulses which is then processed by the microcontroller and the error correction is done using the Huffman algorithm. Finally, the predicted data is displayed as the output, thus we use a simplex data communication system to demonstrate underwater wireless optical transmission.

Morse Code, On-Off Keying OOK, Twilight zone, Huffman Algorithm