The transmission of modulated visible or infrared (IR) beams across the atmosphere to produce Broadband communications is known as free-space optics (FSO), sometimes known as free-space photonics (FSP). Laser beams are most employed, however non-lasing sources such as light-emitting diodes (LEDs) or infrared-emitting diodes (IREDs) can also be used.

FSO theory is substantially the same as fibre optic transmission theory. The distinction is that instead of being steered by an optical fibre, the energy beam is collimated and delivered through clear air or space from the source to the destination.

Working of FSO:

Using low-power infrared lasers in the terahertz range, Free Space Optics (FSO) sends invisible, eye-safe light beams from one “telescope” to another. Laser light is focused on extremely sensitive photon detector receivers in Free Space Optics (FSO) systems to transmit light beams. These receivers are telescopic lenses that gather photons and send digital data that may include Internet communications, video images, radio signals, or computer files. Commercially available systems have speeds ranging from 100 megabits per second to 2.5 gigabits per second, with demonstration systems reporting data rates of up to 160 gigabits per second.

Characteristics of an effective FSO:

• FSO systems should be capable of operating at higher power levels over longer distances.
• High-speed modulation is critical for high-speed FSO systems.
• Because of its upkeep, an overall system design should have a small footprint and low power consumption.
• FSO systems should be able to function in a wide range of temperatures, with less performance deterioration for outdoor systems.
• The system’s mean time between failures (MTBF) should be more than ten years.
Applications of FSO:

• Without the cost of specialised fibre optic connections, FSO systems can cross numerous buildings in corporate and campus networks to provide ultra-high speeds.
• In crisis circumstances where local infrastructure may be damaged or unreliable, temporary FSO linkages can be set up in a matter of hours.
• FSO technology, which is equipped with effective targeting, acquisition, and tracking algorithms, can be utilised in ground-to-air and air-to-air links for airborne vehicles like planes, unmanned aerial vehicles (UAVs), high altitude platforms (HAPs), and balloons, among others.
• FSO technology is a strong contender for supporting high-quality video transmission.
• For Broadcasting purpose, a FSO link can provide the requisite high-quality transmission between the camera and the vehicle.


• FSO systems are capable of operating over long distances. Communication is potentially conceivable if there is a clear line of sight between the source and the destination.
• Even if a direct line of sight is not possible, strategically placed mirrors can be used to reflect the energy. The beams flow through glass windows with little or no loss of energy.


• FSO systems have several drawbacks, even though they can be a reasonable option for some broadband networking demands.
• The fact that rain, dust, snow, fog, or smog might impede the transmission line and shut down the network is the most crucial factor.