What is Free Space Optics?
Free space optics (FSO) or optical wireless technology utilizes visible or near infrared wavelengths to transmit data through the atmosphere in free space. It works similar to optical fiber communication but uses free space instead of fiber as a transmission medium. FSO employs highly collimated light beams which are modulated to carry communication signals over moderate distances. Some key attributes of FSO include license-free operation, security, and immunity to electromagnetic interference.
How does FSO work?
An FSO system comprises of an optical transmitter and receiver which are pointed directly at each other to establish an optical communication link. The transmitter utilizes laser diodes or LEDs to generate a collimated light beam modulated with the signal to be transmitted. This light beam propagates through the atmosphere towards the receiver location. At the receiver, a photodiode or similar photo detector converts the optical signals back into electrical signals which are demodulated into data.
The communication distance depends highly on factors like transmitter power, receiver sensitivity, transmitter and receiver diameters, weather conditions etc. Typically, Free Space Optics Communication links can extend up to 2-3 km but with high powered lasers, distances over 10 km can also be achieved. For longer distances, multiple FSO links may be combined using relay nodes. Precise alignment of transmitter and receiver is crucial to maintain adequate optical power levels through atmospheric disturbances.
Benefits of FSO Technology
License-free operation: FSO utilizes unregulated infrared wavelengths in the spectrum and hence does not require any licensing like radio frequency (RF) spectrum. This makes deployment very convenient without governmental clearances.
High bandwidth: FSO technology offers multi-Gbps data rates and much higher capacities than traditional wired or wireless networks. With continuous advances, Tbps links are also within reach.
Security: Thanks to the narrow, invisible laser beams used for transmission, eavesdropping is virtually impossible unless the receiver location is known. Optical signals cannot pass through opaque objects either, providing physical layer security.
Immunity to electromagnetic interference: FSO networks are not impacted by radio frequency interference that plagues traditional wireless systems. Underwater or indoor operation also becomes possible due to the use of infrared light.
Low cost: FSO connectivity solutions have relatively lower deployment and operational costs compared to laying fiber or microwave links.
Applications of FSO
Campus/office connectivity: FSO has emerged as a cost-effective Ethernet backhaul alternative in connecting buildings within campuses and corporate offices across short distances. It addresses the challenges faced by traditional cable installations.
Oil and gas industry: FSO links are used extensively in offshore oil rigs/platforms for real-time monitoring and control. They provide reliable high-speed connectivity in harsh, explosive environments.
Military use: Due to its security, mobility, and interference resilience, FSO finds use for applications like real-time video transmission, command and control in defense forces globally.
Disaster relief: Temporary FSO links can be set up rapidly during natural calamities/emergencies to facilitate communication where infrastructure has been disrupted.
Cellular backhaul: Mobile operators employ FSO for extending network coverage and as fiber-like cellular backhaul to areas where fiber deployment is difficult.
Challenges and Future of FSO
Adverse weather: Clouds, fog, snow or rain can all impact the outdoor transmission range of FSO links due to scattering and absorption of the optical beams. Mitigation techniques include more powerful lasers, adaptive optics, and automatic shutoff during outages.
Difficult alignment: Initial alignment of narrow transmit and receive apertures over long distances requires precision, especially in dynamic environments. Self-aligning mechanisms and wide-field transmitters help address this challenge.
Eye safety: Concerns over high power laser usage have led to strict regulation and certification of transmitter power levels to avoid retina damage during operation and maintenance. Manufacturers ensure adherence to safety norms.
With continuous technology innovations, the reach and performance of FSO systems will keep improving. Wavelength division multiplexing combined with advanced modulation formats are pushing link capacities to multi-Tbps levels. Integrated terminals and self-powering designs promise truly plug-and-play solutions. Wider commercialization and standardization will see FSO become a mainstream connectivity alternative globally. Its unique attributes make it especially well-suited to provide ubiquitous high-speed wireless access in both developing and developed regions alike.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it