OFC vs FSO | Difference between OFC and FSO
This page compares OFC vs FSO and mentions difference between OFC and FSO.OFC stands for Optical Fiber cable where as FSO stands for Free Space Optics.
Introduction:
Both OFC and FSO technologies are associated with optical domain. OFC uses cables for transmission of modulated light from one end to the
other where as FSO uses air as transport medium. Based on channel and other parameters such as
range, data rate and security, following section mentions difference between FSO and OFC.
OFC | Optical Fiber Cable
An OFC is a type of cable which has number of optical fibers bundled together and covered in their respective protective plastic covers.
These OFCs are used to transfer data signals in the form of light up to distances of hundreds of miles at higher throughput than electrical cables.
All OFCs use core of hair like transparent silicon covered with cladding (having less refractive index) to avoid leakage of light to surroundings. These fiber optic cables are used for various application across wide variety of industries such as medical, Data storage, telecom, networking, broadcast/CATV, internet broadband etc.
The block diagram shows typical optical communication system consisting of transmitter, OFC and receiver. Transmitter part contains encoder and LED/Laser Diode where as receiver contains photo detector and decoder.
Following are the advantages of OFCs (Optical Fiber Cables) .
• They offer much greater bandwidth than metal cables.
• They offer low power loss than copper. Hence it supports distance of about 2 Km than copper (~100 meters).
• OFCs are immune to ElectroMagnetic Interference. Moreover electrical noise does not affect optical fiber cable.
• OFCs support 4.5 times higher capacity than wire cable with 30 times less cross sectional area.
• OFCs are much thinner and lighter.
• OFCs are difficult to tap and undetected physical tapping requires greater skills. Hence OFCs are more secured for
carrying sensitive data than FSO.
• It has greater tensile strength. Moreover it is flexible and resists most corrosive elements.
FSO | Free Space Optics
It is also optical communication technique for transporting data wirelessly using free space as transport medium, Free space means air, vacuum or outer space or similar in contrast with OFC. Like OFC, FSO is also used in telecommunication and computer networking. The common applications are MAN, last mile access, backhaul, enterprise connectivity, fiber backup and service acceleration.
FSO system uses light waves for transmission of data between two buildings which are in LOS (Line of Sight) of each other. The block diagram shows typical FSO system consisting of transmitter, atmospheric channel (i.e. air) and receiver. Like OFC, FSO Transmitter also consists of data encoder and LED/LD (Laser Diode) along with its driver where as FSO receiver consists of photo detector, signal processing module and data decoder.
FSO works on two wavelengths viz. 800 nm and 1550 nm.
Following are the advanatges of FSO system.
• As it uses air as transport medium, no permission is needed for transmission of laser beams. Hence it is license free operation.
• Installation is easier and fast. Moreover maintenance time is short.
• The cost is moderate.
• It has ability to operate at higher power levels.
• It offers higher bit rates and lower bit error rates (BERs).
• The system is immune to EM (Electromagnetic) interference.
Difference between OFC and FSO
Following table compares OFC vs FSO and mentions difference between OFC and FSO.
| Specifications | OFC | FSO |
|---|---|---|
| • Full form | Optical Fiber Cable | Free Space Optics |
| • Transmitting medium | Cable (Single mode and multimode OFC) | Space or Air |
| • Licensing | Required for laying of cables | Do not require as it uses air as medium |
| • Installation and maintenance | Difficult | Easy |
| • Cost | Expensive | Cheaper than OFC |
| • Mobility | Not feasible once laid out | Possible due to its system components and medium of transportation |
| • Security | Difficult to intercept due to cable as medium which is hidden and hence it is more secure. | Easy to intercept due to air as medium which is open and hence it is less secure. |
| • Data rate or speed | 100 Mbps (Up to 2 Km), 1 Gbps (Up to 1000 m) or 10 Gbps (up to 550 m) based on distance | Maximum 10 Gbps (Line of Sight) with full duplex connectivity |
| • Transmission distance | Up to 2 Km (100BASE-FX) using multimode OFC | About 1.5 Km (At 155 Mbps data rate) |
| • Applications | Point to Point (long distance) | Between buildings, last mile solution (short distance) |
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