In case you do not know yet, an optical fibre is a flexible and transparent fibre made of extruded glass (silica) or plastic, slightly thicker than a human hair and able to transmit light between the two ends. with very limited losses.
The main advantage of optical fibre communication over electrical cable transmission is its high bandwidth capability over long distances due to the extremely low loss at the same specific wavelengths (e.g. 1300 nm and 1550 nm). Moreover, optical fibers are also immune to electromagnetic interference, whilst copper wires act as antennas, collecting EM radiation and turning it into current (EM interference).
But let’s have a better look at the main differences between a standard optical fibre and copper cable.
Fibre optics are: Faster
When it comes to data transfer, speed is of the essence. Fibre optics, with its ability to transmit information using pulses of light, surpasses copper cables by leaps and bounds in terms of speed. While copper cables rely on the movement of electrical signals, fibre optics can achieve speeds that leave their metallic adversaries in the dust. With fibre optic cables, data can travel at astonishing rates, reaching mind-boggling speeds of up to billions of bits per second.
Fibre optics are: Safer
The fibre is nonconducting and is therefore safe in all electromagnetic environments. This means it can safely be used around electrical transmission lines, as well as in high RF and magnetic fields. A broken or damaged, optical fibre can be detected extremely quickly by monitoring the actual power transmission. With a suitable circuit, the laser transmission can be shut off within 1-2 microseconds.
At a 1 kW laser power level, even a worst-case fibre break releases at most a few mJ of laser power, with no high-temperature arc. By contrast, a break in a 1 kV electrical power cable will almost certainly result in an arc discharge and unless great care is taken in the circuit design to detect arcs and minimize energy storage, the arc can persist for milliseconds and deliver joules of energy.
Both high voltages and high-power lasers are potential hazards to users or (particularly) service personnel; both hazards can be readily mitigated in most cases by suitable safety interlocks. We do note, however, that high voltage, high current sources can kill if even a small fraction of the power escapes; laser sources can cause eye damage and in extreme circumstances burn skin, but cannot be lethal.
Fibre Optics are: Lighter
For many combinations of power and distance, optical fibre is much lighter than any practical electrical cable.
At voltages below ~1,000 V, electrical conductors are much heavier than optical fibre for similar power delivery capacity. Conductor weight tends to scale as 1/voltage^2 (because power loss varies as V^2/R), so even at 400 volts, copper weighs over twice as much as fibre. Aluminium conductors are roughly half as heavy as copper for equivalent resistance but still heavier than our best estimate for optical fibres, even with no insulation. However, aluminium is much lower in strength than copper and is more difficult to make into fine, highly flexible cables.
Fibre optics have: No RF Interference, Emissions, or Inadvertent Antenna
An optical fibre has no RFI/EMI issue because it is not a conductor. Because light cannot pass through walls like electricity can, an intruder would need physical access to an optical cable before being able to intercept any data travelling through it; this makes it much more difficult for hackers to gain unauthorized access to sensitive networks protected by fibre optic cables than those connected by copper wire alone.
Copper wire, on the other hand, can leak signals and can be impacted by RFI. It can act as an antenna, interfering with data being sent along the cable. In extreme cases, copper wire can pick up energy from nearby high-power transmitters, not only interfering with data transmission but potentially overheating the wire.
Fibre Optics have: Higher Data Bandwidth
Multimode optical fibre can readily transmit high bandwidth data over long distances; a typical bandwidth-distance product for multimode fibre is 500 MHz/km, so a 500 m tether can transmit 1 GHz. Signal losses over 500 m are negligible; the bandwidth is limited by the dispersion of signals.
This makes optical cables ideal for use in places where traditional copper wiring would not be feasible, such as deep underground mines or across large bodies of water. Additionally, because they are made out of light-transmitting materials (glass or plastic) rather than electricity conductors (copper), optical fibres do not suffer from signal interference from nearby power lines or other electric sources which can degrade the performance on copper cables.
Lightweight copper cable, by contrast, has very high losses at high frequencies. Twisted pair optimized for high data rates (Cat 6) can transmit 500 MHz over only 100 meters (bandwidth-distance product of 50 MHz/km); lightweight unshielded cable optimized for power transmission will have an even lower bandwidth-distance product.
Both Fiber and Copper are: Reasonable in Terms of Durability
The ultra-pure silica glass used in optical fibre has a higher tensile strength than copper. The jacketing material further strengthens and protects the fibre. The toughness of fibre optic cables is well understood. The durability of very fine copper wire without thick insulation is not as well understood.
Fibre Optics and Copper are: Similar in Terms of Price
While fibre optics may be initially more expensive for short links due to the cost of the lasers and detectors involved, they become much more cost-effective over longer distances. The advancements in fibre optic technology and increased manufacturing efficiency have significantly lowered the overall costs of fibre optic cables.
Additionally, the durability and longevity of fibre optic infrastructure reduce the maintenance and replacement expenses associated with copper cables, making fibre optics a cost-effective solution in the long run.
Conclusion: Optical Fibre vs Copper Cable
Optical fibres and copper cables are both used to transmit data, but they have different strengths and weaknesses. Optical fibres are faster and have a higher bandwidth than copper cables, but they are also more expensive. Copper cables are less expensive and easier to install than optical fibres, but they have lower bandwidth and are not as well-suited for long-distance transmission.
The best choice for a particular application will depend on the specific requirements of that application. For example, if you need to transmit data over long distances at high speeds, then optical fibres are the better choice. However, if you are on a budget and need to install a network quickly, then copper cables may be a better option.
Anything missing? Let me know in the comments below.
References
- “A Comparison of Optical Fibers and Copper Cables” by M.J. O’Hara, published in the journal IEEE Communications Magazine in 2002.
- Advantages of Fiber Optics Cables over Copper Wires
