Development of an FPGA based Indoor Free Space Optical (FSO) Communication System using 808 nm Infrared (IR) LASER Source

With the advent of Wireless networks, the communication industry has swelled up to a commendable level. Today, communication link establishment between any corners of the world is not a myth anymore because of the research and development of the vast wireless networks. Another technology that serves as the skeleton of these wireless networks is the Optical fibre communication system. The part of the electromagnetic spectrum utilized in the Wireless networks mainly includes the Radio frequency (RF) range and the Microwave range (3 kHz to 30 GHz) which requires broadcast licensing. With the ever-increasing number of users, the allocation of the RF spectrum becomes a major issue. Other disadvantages of the RF and microwave wireless networks have compelled researchers to develop other parallel technologies. One of the mentionable recent technologies that gained fame is the Free Space Optical (FSO) Communication System which combines both the aforesaid technologies into one. This new technology exploits the Visible (400-700 nm) and Infrared (700 nm- 1 mm) region of the EM spectrum. This paper interprets the development of a Field Programmable Gate Array (FPGA) based half duplex terrestrial FSO Communication system using an 808 nm (IR), 100 mW DPSS LASER source. The Line of Sight (LOS) communication link distance is 40 feet. The communication protocol implemented in the design is Serial Communication with a data rate of 115.2 Kbps and the modulation technique used is On Off Keying (OOK).