What would happen if you..... (deep thought)... please read

[Arin 0]

What would happen if you took a fiber optic cable that was wrapped around the earth a couple times flashed a laser into it, and then connected both ends of the fiber optic cable before the light left the cable. light goes for ever, so would it keep going if the connection was 100% flush with with the other end of the cable? Think about it, what would happen?

 

 

[EM 0]

Even the best Fiber optic cable has attenuation loss at some wavelength. For instance, most fiber optic cable utilized in CATV applications using a 1330nm wavelength has an attenuation factor of about 0.4dB per km. So there is no way that the "light will go on forever". However, depending on the strength of the light inserted from your laser, it may go on for a while.

 

Ed

[Arin 0]

so even if it was coated in black or some thick metal, do you think it would die out, and it would be cool to see.

[Jabba 0]

It's the same idea as a perpetual motion device. There's no such thing as a frictionless media, just as there's no such thing as a 100% efficient fiber optic cable.

Can't be done... at least not with today's technology.

[Dragon-Lord 0]

Light in a perfect vaccuum (i.e. not space).

[euankirkhope 0]

IF you use Eribium Doped Fibre Amplifiers, the light could go on for ever with out having to be amplified through electronic circuits (which slows it down big style).

 

Erbium had the distinct properties of having a 3 level energy state:

Code:

    E2 ---------    E1          --------                    ----->980nm --->    =     -----> (amplification)                    ----->    E0 ------------------

(sorry if the diagram screwed up, trying code this time)

 

Photons = --->

Photon Energy E1-E0 = 1550nm (the TX wavelength)

 

Now with a fibre and laser at 1550nm

if you couple the 980 laser into the main fibre, by means of the Evanescent field (electromagnetic field generated by the photon, as the light is reflected back into the fibre, it actually momentarilly protrudes the fibre), the 980 laser (pump photons)will then exite the electrons in the Erbium to move up to E2 from E0, but they quickly drop to E1 in a rapid non-radiative transistion, this creates a population inversion, and as the 1550nm light passes through the medium, spontaneos emmision of photons occurs as the E1 electrons drop down to E0, thus amplifing the original signal by up to 30dB (1000x). And while still traveling the speed of light!

 

Using the above and Wave Division Multiplexing you can get 3.2Tb/s (terra) down one fibre (IE the width of a hair, and done in recent AT+T research).

 

However there are important issues with wrapping that fibre around the world, and that is the Br.L factor. As the link length increases the bit rate will go down due to the effect of Pulse Spreading, where the original short pulse becomes widened in time,thus you have to slow down the bit rate or you lose the definition of each pulse.

 

[This message has been edited by euankirkhope (edited 31 March 2000).]

 

[This message has been edited by euankirkhope (edited 31 March 2000).]

[Jabba 0]

wow.

[tylau 0]

How about the fibre optic replaced by a "super conductor" with an initial current (charges) pumped through it?

[Jabba 0]

Basically anything that served the above function would BE a superconductor.