Meaning
Optical communication through the atmosphere provides high-bandwidth wireless connectivity between distinct transceivers. A free space optical link utilizes collimated laser beams to transmit data without physical fiber connections. This technology provides high-speed data transmission in urban environments where laying cable is impractical or prohibitively expensive.
Atmospheric Attenuation
Signal degradation along the optical path occurs due to scattering and absorption by airborne particles. Fog, rain and dust scatter the infrared radiation, which causes fluctuations in the received optical power. To mitigate this signal loss, high-power transmitters and advanced error-correcting codes are implemented in the system.
The power budget must account for seasonal weather variations to guarantee reliable operation throughout the year.
Alignment Tracking
Narrow beam divergence requires continuous alignment between the transmitter and the receiver. Dynamic gimbal systems and fast-steering mirrors compensate for structural sway and thermal expansion in the mounting buildings. This active tracking ensures that the collimated beam remains centered on the detector array during operation.
Receiver Sensitivity
The minimal detectable power of the receiver determines the maximum operational range of the free space optical link. Avalanche photodiodes are frequently employed due to their internal multiplication gain. This choice improves the signal-to-noise ratio in weak signal conditions.
