hello.
i agree with all the responses. i just want to add that Free space optical (FSO) communication is similar to VLC but is not constrained to visible light, so ultraviolet (UV) and infrared (IR) also fall into the FSO category. Additionally, there is no illumination requirement for FSO and so this tends to be used in narrow beams of focussed light for applications such as communication links between buildings. FSO often uses laser diodes rather than LEDs for the transmission.Optical Wireless communication (OWC) is a general term which refers to all types of optical communications where cables (optical fibres) are not used. VLC, FSO, Li-Fi and infra-red remote controls are all examples of OWC.Long-haul fibre took a long time to be fully adopted. Initially in the late 1980s and early 1990s there was good supply of new fibre capacity and a lack of demand but then the Internet came along and changed that. Point-to-point links between buildings have traditionally been microwave, but there is now a growing shift towards free-space optical (FSO) links giving Gbit/s capacities using lasers.
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