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FrozenGate by Avery

Possible way to turn a 200mw to a 99999MW laser in

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wooooooolazer

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I got to thinking, if there was a mirror out there that was only reflective on one side and let all of the other light thru, like if you shined the laser on one side of it it would reflect 100% and if you shined it on the other it would pass 100%.  Is this even optical possible?


Say you shined a laser thru the side that pased it then that hit another mirror bouncing back to the laser but hitting the lens and reflecting back onto the other mirror and repeating, with the laser continualy adding light to that reflection it would keep going up in power  a second of doing that the laser would go up in power to the MW probably more since it does move at the speed of light.

P.S. Lets just hope this wouldnt break some fundamental law of physics causing a black hole and destroying all matter in the universe... That would be bad 8-)

...lazer.... ;D ;D ;D


Heres a pic to help you understand [smiley=smiley_down.gif] [smiley=smiley_down.gif] [smiley=smiley_down.gif]
 





Re: Possible way to turn a 200mw to a 99999MW lase

You are referring to an "optical diode" and they do exist.

The effect your describing is pretty much the same thing that occurs in a high-Q laser cavity.  The intra-cavity laser beam power is enormous compared to the laser beam that gets emitted.  The problem is that tapping into the intra-cavity power spoils the Q.
 
Re: Possible way to turn a 200mw to a 99999MW lase

is that the basic way a laser operates is it usses one simi transparent mirror on the front and one complete reflective mirror in the back and lights bounces back in forth striking more electrons releasing alot of corrent light? at leasts thats what i have read in my physic book
 
Re: Possible way to turn a 200mw to a 99999MW lase

well in that case one of the mirrors is reflective on one side and its more like 50% reflective, it bounces back and forth until it reaches unough power and just goes right thru it, its sorta the same but differnt to.

...lazer... ;D ;D ;D
 
Re: Possible way to turn a 200mw to a 99999MW lase

knimrod said:
You are referring to an "optical diode" and they do exist.

The effect your describing is pretty much the same thing that occurs in a high-Q laser cavity.  The intra-cavity laser beam power is enormous compared to the laser beam that gets emitted.  The problem is that tapping into the intra-cavity power spoils the Q.
Click to expand...


Well sinse it would go back to power in a fraction of a second couldnt you just somehow get it to pulse every half a second and while its waiting for another pulse it would just build back up.

...lazer.... ;D ;D ;D
 
Re: Possible way to turn a 200mw to a 99999MW lase

Fascinating... Mr. Scott..... ;D

I always like it when people are thinking.......

I just want a laser strong enough to put a dot on the moon "the darkside" that everyone can see from the earth when its in crescent ...... then I'll work on the light side!
 
Re: Possible way to turn a 200mw to a 99999MW lase

wooooooolazer said:
Well sinse it would go back to power in a fraction of a second couldnt you just somehow get it to pulse every half a second and while its waiting for another pulse it would just build back up.

...lazer.... ;D ;D ;D
Click to expand...

Now your talking about a form of "Q-switching" called "cavity dumping". A high-Q cavity would use 100% reflective mirrors and use a Q-switch to dump the beam from the cavity in a pulse. There's also regenerative amplification where a laser pulse is injected into a low-Q cavity, increasing the Q to confine the injected pulse to the cavity where it can be amplified by repeated passes through the gain medium, and then dumped with a Q-switch.
 
Re: Possible way to turn a 200mw to a 99999MW lase

The concept is present in some pulsed lasers. However mirrors like that don't exist. If they were, they would be utilized instead of dichroic mirrors. Also, no process is 100% efficient.
 
Re: Possible way to turn a 200mw to a 99999MW lase

The bad thing is that if it isint 100% effecient then some of the light will go back onto the diode killing it, i also forgot to include about divergance, since the amount of area it would cover in a second is 860,000 miles that would mean it would have a dot size of like miles so if you tried it with the mirrors wouldnt it make a dot that size?

all that highQ and lowQ stuff you posted about is way over my head for now lol :D

...lazer.... ;D ;D ;D
 
Re: Possible way to turn a 200mw to a 99999MW lase

Theres one thing you are forgetting. The crystals can't handle that much power, so it will end up killing itself. If you shine a laser into another laser, it will usually go out untill you move it away again.
 
Re: Possible way to turn a 200mw to a 99999MW lase

no, it will usualy break ;D... well atleast diodes do, i know from experience.

That is why it would have to be 100% effeciency in reflecting the light and not letting it back thru, which unfortunantly isint posible.

...lazer... ;D ;D ;D
 
Re: Possible way to turn a 200mw to a 99999MW lase

So basically what your trying to do is make your own resonate optical cavity.
 
Re: Possible way to turn a 200mw to a 99999MW lase

In reality, reflection losses will be your enemy.

Still, I wonder how you want to get that beam out of the cavity? Optical switch? Because I have seious doubt that any mechanical device is fast enough?

Also, following the example of the thread-title, of having a 200mW Laser create a 100GW pulse, even with perfect mirrors, it would take you 5*10^10 seconds, or more than 1.5 millenia (1584 yrs, to be a bit more specific) to build it up...


ah crap, sorta messed up there...depens on how long your cavity is....but to create a 1s-100GW pulse, the above time is needed.
 
Re: Possible way to turn a 200mw to a 99999MW lase

okay, here's the deal:
Beam gets into cavity, hits opposite mirror, returns. Once it gets reflected on the semi-reflective mirror, it adds with the "fresh" beam coming in.
If cavity length is "l" (lowercase L), then the beam's intensity is n*input power after it "flew" 2*n*l
With c = 3*10^8m/s (yeah, I'm metric and inaccurate), power increases every 2*l/c seconds.

Example: let the cavity be 1cm (.4 in) then you have double input power after about 6 ns.

But - the shorter the cavity, the faster power builds up, but the less enegry is in there (well, no, energy contained is the same, much rather, how long the power can be held up will decrease).

so taking the time it takes to build up will be the time you have at hands to use your 100GW.
Say we use above 1cm-cavity again, then after 333 seconds (about 5 1/2 minutes), you will have a 6ns 100GW pulse available.

Neat, huh? Decreasing charging time is fully flexible, just shorten cavity. Need longer burst? Just make it longer!
And it can all be calculated with the simple formula of P(out) = P(in)* t *c /(2l) and t(out) = 2l/c





now about that semi-mirror: If one were to mke a sphere out of that, reflecting side on the inside (outside), what would be the temperature inside? Would it continuously increase (decrease), until it hits the temperature of the radiation going inside (reaching absolute zero)? Or would it, in the reflecting inside case, continue increasing, as no enegry is given off? In the reflecting outside case, assuming zero heat transfer, would it hit absolute zero or would it be an asymtotic process that never hits zero?
 
Re: Possible way to turn a 200mw to a 99999MW lase

It is called a power build-up cavity, they are used when you need really high CW intensities or sometimes as a frequency stabilization technique. You have to build it with high reflecting mirrors on both sides and you have to use at least one concave mirror, otherwise the beam would expand as it bounced back and forth. The high reflective mirrors only let in like .01% of the laser, so it takes a while to build up. Also you need to have it built on something very stable so the mirrors stay an exact distance apart, otherwise if the mirrors are not spaced by exactly N wavelengths you will get destructive interference and you will never get power to build up.

Oh yeah, and philguy seemed to capture the relevant physics.

And if you did want to get that light out of the cavity you use a fast optical switch called a pockels cell, they can switch in as little as 100 ps.
 
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