Free Space Optics (FSO) or Optical Wireless, refers to the transmission of modulated visible or infrared (IR) beams through the air to obtain optical communications. Like fiber, Free Space Optics (FSO) uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, it is transmitted through the air. It is a secure, cost-effective alternative to other wireless connectivity options. This form of delivering communication has a lot of compelling advantages.
Data rates comparable to fiber transmission can be carried with very low error rates, while the extremely narrow laser beam widths ensure that it is possible to co-locate multiple transceivers without risk of mutual interference in a given location. FSO has roles to play as primary access medium and backup technology. It could also be the solution for high speed residential access.
Free space optical (FSO) communication has emerged as a viable technology for broadband wireless applications which offers the potential of high bandwidth capacity over unlicensed optical wavelengths. Atmospheric turbulence has a significant impact on the quality of a laser beam propagating through the atmosphere over long distances. For optical wireless communication systems, most frequently used system is Intensity Modulated Direct Detection (IM/DD) system. For FSO systems, although the power efficiency is inferior to PPM, On Off Keying encoding is more commonly used due to its efficient bandwidth usage and robustness to timing errors.