An important aspect is its alignment tolerance, i.e.
Therefore, the design of the receiver tends to be more crucial than the design of the transmitter. The main objective of the receiver is to collect as much as possible of the incoming signal and to couple it either to a photodetector or an optical fiber. Moreover, a desired feature of the transmitter optics is that it should add a minimum of aberrations (specially spherical aberration). Without transmitter optics, the beam divergence would produce a beam too large to be of practical use (around 200m a distance of 500 m). The main purpose of the transmitter optics is to produce a suitable beam divergence matching a desired beam diameter at the receiver. The reason for this is due to the lower absorption at those wavelengths, although additional development exists at longer wavelengths (>5 micrometers). In terms of wavelengths, most FSO systems operate in the near-IR wavelength range between 7 nm. To properly design an FSO system, we need to define requirements including range, data rate, and price. Majumdar “Optical Wireless Communications for Broadband Global Internet Connectivity. Different types of FSO communications a) Optical Interconnects, b) point-multipoint indoor FSO, c) Terrestrial FSO, d) satellite FSO.
On the downside, FSO communication is affected by the mentioned atmospheric effects, which limits sensitivity and achievable data ratesĪlthough the field of FSO also includes optical interconnects and satellite communications, here we will focus on systems where a line of sight between two ground-stations exists.įigure 1. For example, FSO networks can be configured for point-to-point, point-to-multipoint, multipoint-to-point, or multipoint-to-multipoint. One of the reasons why FSO are so attractive is because they offer great flexibility and relatively low cost to be deployed while providing high transmission data. What are Free-space Optical Communications?įSO are communication systems in which the signal is propagating through the air or vacuum.
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