FSO

Free-space optics (FSO) is a line-of-sight optical wireless communication technology that transmits data through air using light signals, typically from lasers or high-brightness LEDs. FSO links emulate a fiber-optic connection but require no physical cable, instead relying on precise alignment between transmitter and receiver optics.

Many FSO systems operate in the near-infrared spectrum—common wavelengths include 850 nm, 1310 nm, and 1550 nm—and can support data rates from tens of Mbps to multiple Gbps, depending on distance, aperture, beam quality, and atmospheric conditions. The link demands careful pointing and tracking, with stabilization, adaptive optics, and error-correction as needed.

Applications include urban wireless backhaul, campus networks, and temporary links for events, disaster recovery, or situations where trenching fiber is impractical or expensive. FSO provides rapid deployment and can supplement or replace fiber in suitable environments; its narrow beams also offer a degree of physical security against interception.

Advantages include high bandwidth, license-free spectrum in many regions, low latency, and immunity to electromagnetic interference. Limitations include performance sensitivity to weather (especially fog and heavy rain), atmospheric turbulence, the potential for misalignment due to building movement, and interference from background light, which can raise error rates. Consequently, many deployments use hybrid configurations with fiber or RF backups.

History and standards: Research and development began in the mid-20th century, with commercial deployment expanding in the 1990s and 2000s. Standards exist for performance and safety from ITU and related bodies, but many products are vendor-specific. See also: free-space optical communication, optical wireless communication.