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#9692 - 05/09/02 08:54 PM Fiber Optic Questions
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
I took an introductory fiber optic class at my local supplier's this evening. Pretty informative, and I got to make a splice (the gel type, no polishing!) Since I was the first volunteer (why will no one else volunteer?) my splice was actually pretty bad, but I was informed that it still complied with the 20dB range... (I tapped a little to hard on the little doo-hickey that nicks the cable at the proper length, and I probably chipped the face a little...)

My main Q is on the theory that I was told of transporting power across fiber...
How is the electrical power converted to light and back? My joke was that is was a bulb on one end and a photovoltaic cell on the other, which would be horribly inefficient... How do they really do it?

How much "light" power does it take to make "x" watts of electricity? I'm under the impression that light and electricity are both electro-magnetism, are they just at different frequencies or is it a bogus comparison? How does it relate?

Was this guy just blowing smoke?

(And will I need to trade in my tools for fiber optic kits?)

_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#9693 - 05/09/02 09:56 PM Re: Fiber Optic Questions
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Virgil,

Fiber Optics is used for the transmission of signals as far as I know of.

A LED or a Laser that is controlled by Electronics sends pulses of light through a Glass Fiber that is 'received' by a photodiode at the other end that converts the pulses of light back into a copy of the original Electronic signal.

Look here for some training info:
http://www.cableu.net/vho/

Bill

[This message has been edited by Bill Addiss (edited 05-10-2002).]

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#9694 - 05/09/02 10:05 PM Re: Fiber Optic Questions
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Ok, that part I can understand when we're talking nanovolts and nanoamps, but let me quote the gentlemen in saying (roughly) in 35 years, this will be replacing all power cables. He went on to give the impression that this has been demonstrated at short distances. He literally was talking about having Fiber replace Romex and SE and URD and triplex, ad infinitum....

How?

Let me add that the same fellow was pronouncing Kevlar: "Kelvar" and Biconic: "Bionic", so a little salt may be required for consumption...

[This message has been edited by sparky66wv (edited 05-10-2002).]
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#9695 - 05/09/02 10:29 PM Re: Fiber Optic Questions
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
I don't have a clue. but 35 years is a long time.

Bill

Here's an interesting concept:
http://www.cableu.net/fibrtech/fiberamp.htm

[This message has been edited by Bill Addiss (edited 05-10-2002).]

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#9696 - 05/09/02 10:56 PM Re: Fiber Optic Questions
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Thanks, Bill. That was an interesting read.

I guess I'm just intrigued by the whole thing and I have nothing but questions at this point.

However, I need to go to bed... (note time)
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#9697 - 05/10/02 05:01 PM Re: Fiber Optic Questions
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Virgil,

Take a look here for some interesting stuff;

.
TECHtionary

Bill

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#9698 - 05/11/02 01:48 PM Re: Fiber Optic Questions
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
Virgil,

I'll throw out a couple of basics in regards to the FDDI thingee [as to LAN cabling]:

1: Your idea of the lamp and photo voltaic cell isn't too far off! The pulses of light are created at the sending [Transmitting] end by an LED. The light is either in the Infrared spectrum or the Ultraviolet Spectrum [LASER diodes push UV light]. Light could also be in the visible white spectrum, but not sure if anyone uses this range.
On the Receiving end, the light pulses are "Picked Up" by either a Photo Doide or a Photo Resistor [Photo Diodes mostly used].
This type of interface is also used on other types of Opto-Isolators, like ones used in NICs [between the PC card and the LAN cabling] and on MODEMS [between the PC card and the Telco line. This establishes an Isolated link.

2: Typical setups would have Transciever arrangements - as do nearly all COM ports. So this makes each end have an LED and a Photo Diode.

3: The true power [watts] would be equal on what's put in and what's put out [if there's no losses]. Pump a Fiber with a 20 ma LED - driven at 22 VDC [giving 2 VDC for the Fowrard Voltage Drop of the LED] and this equals 0.4 watts. If this transforms into an equal lighting power, that is the total true power being pushed through the fiber pipe.

4: You are under the impression that Light and Electricity are both Electro-Magnetic Radiation ??? Where did you get that from? Couldn't have been from me!!

Now with the jokes over, you have figured CORRECT!!! [Time for a cigar!]

The Electro-Magnetic Radiation spectrum begins with VLF [Very Low Frequency] and this covers 0 to around 100 Hz. Audio Frequency "rolls over" the 100 Hz mark [beginning around 20 Hz] and runs thru 20Khz. Next is AM Radio stuff, then High Frequency, then VHF [covers the HAM radio guys, plus TV channels 2-13 and FM radio]. Next is UHF, then it steps into Microwaves [ovens and cell phones]. Next steps are the Infrared regions. After that comes the very narrow band of visible white light [tiny as compared to the other bands!]. This is followed by the Ultra Violet regions. After this comes the X-rays, Gamma Rays and Cosmic Rays.

Anyhow, just wanted to ramble this out!

Scott SET
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#9699 - 05/11/02 04:28 PM Re: Fiber Optic Questions
maintenanceguy Offline
Member

Registered: 12/02/01
Posts: 303
Loc: Southern NJ, USA
Power in won't equal power out with a fiber optic cable.

The lazer diode used to send the signal might produce a pulse of light with an energy close to the electrical energy used to "fire" the lazer.

But once it reaches the other end, the photodiode used to "see" the light signal is just a switch. It doesn't provide any usable power. The recieving end needs its own power supply to do anything with the signal, even to "see" the signal.

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#9700 - 05/11/02 05:33 PM Re: Fiber Optic Questions
motor-T Offline
Member

Registered: 11/10/01
Posts: 293
Loc: Girard, Ohio, USA
To All:
Is it so far fetched to believe that in 35 years our industry as we know today will be totally unrecognisable.
I mean who would have thought that just 25 years ago where Pac-Man would lead, with a computer to the internet and a Credit Card we dont even have to leave our home.
Or that the Navy talks to its Subs with the same VLF that scott was talking about and the Subs can here with out even surfacing.
Fibre Optics started on the premise of total internal reflection, and if they ever reach the point of 'Super conductors' Why not replace romex wiht a fiber optic cable, I suppose the only thing to worry about then will be a leak.

-Mark-

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#9701 - 05/13/02 09:01 AM Re: Fiber Optic Questions
BuggabooBren Offline
Member

Registered: 11/15/01
Posts: 336
Loc: NM
The only thing I found was an article that I initially thought pointed in exactly the direction your instructor implied - power being delivered over fiber optic cable. Upon further reading, it appears the opposite - power cables being outfitted to support the fiber optic cable (technically two separate cables strung together or integrated):
http://www.enn.com/news/wire-stories/2001/05/05152001/upi_composite_43551.asp

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