The conversation started as a wireless "laser" transmission application to, now, fiber optics.

How do you think the light "gets in" the fiber -- lasers and leds.

Electrical cables can carry a lot more power than an optical cable. Transmitting through the air results in huge losses in proportion to the distance. As was mentioned earlier you have a <1% efficient laser transferring it's energy to a 20% efficient photovoltaic so the net is .02% max.

 

I'm sorry I emphasized the "laser" portion of my post intead of "wireless". I am just confused as to whether this is supposed to be a wireless project or something else. Thanks for the clarification though.

 

I think the discussion drifted away from wireless because it is too lossy for "real" power transmission. Plus it would prone to vary due to humdity, dust etc. If the OP just wants to demonstrate power transmission then a laser beam into a solar cell could work.

As far as a the earlier question about matching the wavelengths.... it would be difficult since the bandgap is different for the PV cell than the laser.

 

wow, I think there is a large communication barrier. The conversation started as a wireless "laser" transmission application to, now, fiber optics. Someone needs to explain what they really want?

Project title: Optical power transmission to replace the existing electrical power transmission
input: laser beam
output: electrical power

 

Means that the optical fiber by itself is very efficiency.
But when to convert the optical power to electrical power, it is very inefficient.
Am i correct?

Compare the optical power transmission with the existing power transmission, which one will cause major problem? Why?

 

Means that the optical fiber by itself is very efficiency.
But when to convert the optical power to electrical power, it is very inefficient.
Am i correct?

You are correct.

Compare the optical power transmission with the existing power transmission, which one will cause major problem? Why?

A CO2 laser will convert around 10% of input electricity into light. As previously mentioned, opto-electric cells have similar efficiency when converting light back into electricity. Total transmission loss would be 99% or more. By comparison, transmission loss over copper can be a fraction of a percent.

Copper wire also costs much much less than lasers and solar cells.

Fiber will soon be the more economical communications medium, but copper will rule the power transmission roost for decades to come.

 

This is my first design circuit..
http://www.sendspace.com/file/aw60wn
can anyone take a look and give some comment..
My desing idea is to shine laser directly in photovoltaic cell and amplify it...
thanks..

Notes: My design goal is convert the laser input into electrical form.

 

Bad link...

 

What is the problems then???

 

This is my design

 

i just plan to shine the laser directly to the photovoltaic cell and then connect it to inverting amplifier...

 

The optical fiber itself is very very efficient it is just that the energy required to "make" the laser light is very inefficient so it is not usually the first method that pops up when you discuss transferring power.

You said it all. Essencially, the lack of efficiency resides in the LASER and in the receptor, since almost no light is lost when traveling through a optical fiber cable.

Means that the optical fiber by itself is very efficiency.
But when to convert the optical power to electrical power, it is very inefficient.
Am i correct?

Compare the optical power transmission with the existing power transmission, which one will cause major problem? Why?

Indeed. So why using an optical cable? You still have a cable, so the "wireless" problem won't be eliminated unless you shine the laser directly. And of course, what could be more efficient than direct and plain electrical transmission. Even with transformers in the middle, a greater efficiency is to be expected out of an electrical power transmission system.

Resuming, you should have defined the goals of this project first thing to avoid confusion. Also, it doesn't seem a reasonable project, unless you want to use the same kind of power transmission systems than the ones used in "Doom 3" and "Quake 4".

 

This will work fine for receiving signals, but not for receiving power.