Why Optical Communication have more bandwidth?

[Anachip]

Hi,

I'm the beginner in optical field. I would like to know why optical communication is said to have much more bandwith than the copper wire. In what sense they are said to carry data in Gigaherz rate compared to copper.

Thanks.

 

[the_risk_master]

I think it is because it operates on the bandwidth of light.

 

[xxargs]

Hi,

I'm the beginner in optical field. I would like to know why optical communication is said to have much more bandwith than the copper wire. In what sense they are said to carry data in Gigaherz rate compared to copper.

Thanks.

Copper can transfer many, many GHz without limits or unliniary, biggest differenses between transfer via copper or optical light is a loss (attenuate) per distance depend of skin-effect incrase loss on copper in sqrt(f) and can go to high value in high frequency (wide bandwith)

for example 7/8"coax-cable in 1800 MHz (~ 2 Gbit/s) can have loss around 4 dB/100m depend of skin effect, but laser modulated with 1800 MHz on fiber give attenuation of 0.035 dB/100m - this difference is very important factor to why optical transmission is so popular for information transport.

but optical have also lot of disadvantage as limited dynamic, limited frequecy range (depend of lasers and optical diode) and unliniarity (both lasers and fiber), cannot transport big power. Only travel as 2/3 of speed of light (air filled coax or between antenna can go near 1) etc.

Optical link better suited for transport information over long distance compare to copper-cable only depend of discovered (very) low loss windows in glass for 1550/1310 nm (or 193 / 229 THz) and yet impossible to find simular 'window with low loss for high frequencys' in copper cable world.

 

[kender]

Another reason is that fiber is less succeptible to "stray light" than copper is succeptible to EMI.

 

[windman]

The most important reason that optic fibre has much higher bandwidth is, simply saying, the carrier on optic fibre is light, which frequency is so high to reach 10^14 Hz. if we just take a mall amount of the carrier frequency(modulation), say 0.05%, it would be 50GHz, that's the case in DWDM communication system. The higher the carrier is, the higher the bandwidth of a system can achieve. Same thing is true for copper wire.