Key Features of Modern Fiber Optic Communication
In fiber optic communication systems, the frequency of the light wave used as the carrier is much higher than that of the radio wave, and the optical fiber used as the transmission medium has much lower loss than coaxial cable or waveguide. Therefore, compared to cable communication or microwave communication, fiber optic communication has many advantages:
It allows for a wide bandwidth and a large transmission capacity:
The frequency of light waves currently in use is 103 to 104 times higher than that of microwaves, which can increase communication capacity by 103 to 104 times. Theoretically, two optical fibers can transmit millions of telephone calls and hundreds of television programs.
It has very low loss, long relay distance, and low bit error rate:
The loss of optical fiber is much smaller than that of coaxial cable, approximately 1.31μm and 1.55μm wavelengths. The attenuation is 0.50dB/km and 0.20dB/km respectively, or even lower. Therefore, optical fiber can achieve longer repeater spacing and higher medium attenuation. For a 1.55μm chromatic dispersion-shifted single-mode fiber communication system, if the transmission rate is 2.5Gbit/s, the medium distance attenuation can reach 150km; if the transmission rate is 10Gbit/s, the medium distance attenuation can reach 100km. Using optical amplifiers and dispersion compensation, the medium distance can be further increased, and the transmission error rate is very low (10^-9, or even smaller). The advantages of large transmission capacity, low transmission error rate, and long medium distance make optical fiber communication systems not only suitable for long-distance trunk networks but also for access network applications. This is the main reason for the systematic cost reduction of optical fiber communication systems per kilometer.
Light weight and small size:
Optical fiber is light in weight and small in diameter, making it easy to form optical cables. Under the same conditions, its weight is much lighter and volume is much smaller than copper cables.
Good anti-electromagnetic interference, known as "radio silence":
Optical fiber is a non-metallic light-guiding fiber, which does not work in a strong electromagnetic field environment near nuclear explosions or strong electromagnetic interference. Optical fiber will not generate induced voltage or current, which is beneficial for transmitting motion images (such as cable TV and cable broadcasting). It is also beneficial for laying near high-voltage power lines and electrical railways without interference. It is also suitable for automated control and measurement systems in factories and mines, as well as for use in flammable areas, on aircraft, and in deep-sea operations. Because optical fiber communication limits transmission within the fiber and does not leak light, optical fiber's own "radio silence" does not suffer from eavesdropping and is not easily damaged.
Abundant resources and economic benefits:
The main raw material of optical fiber is silica, whose storage in nature is extremely rich, with practically unlimited reserves. The use of optical fiber can save a large amount of copper materials later on. Manufacturing 1×10^4km of single-mode fiber copper wire consumes approximately 2.64×10^11J of energy, equivalent to a standard coal consumption of 9×10^5kg. Due to the large capacity of optical fiber communication, long medium distance, saving of non-ferrous metals and auxiliary materials, it is therefore more economically beneficial than copper.
Corrosion-resistant, not afraid of moisture:
Even if the outer protective layer of optical fiber has small holes or cracks allowing water or moisture to enter, it will not affect the transmission of light, but water and moisture can corrode metal conductors and cause grounding and short circuits. Optical fiber communication systems also do not have the risk of fire caused by sparks, and have good safety.
