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Lasers in nature??

chipdouglas

chipdouglas

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Hey guys. I did not google this because I enjoy reading the discussions and explanations here....

Are there natural lasers. Meaning, does stimulated emission take place naturally anywhere, here on earth or else where? Or does any part of the laser making process take place anywhere in nature?


Michael
 





Lots of high energy photons are spewed out of young stars, black holes, and other stellar objects which ionize nearby gas clouds.
This matter will emit radiation either as heat or light.
Auroras are not unique to Earth. High energy particles create light in the ionosphere.
So light is produced in many different ways on Earth and in space...

But I don't know if stimulated emission like what we get from lasers can be done without an artificial apparatus. I suppose coherence would be the determining factor that separates other sources of light from "laser" light.
Although nature does all kinds of crazy things so I wouldn't be too surprised...
 
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I read an article of it taking place in space across a stupidly large cloud of gas, but it was far IR.
 
^^^^ stimulated emission, coherent light or both? Also, are lasers the only form of coherent light.
 
What most people don't understand is that the light isn't coherent for more than few cemtimeters in most cases. Your beam still behaves like a beam 10 meters out, but the coherence is long gone. You need a laser for coherence, but you do not need coherence for a laser. Stimulated emission defines a laser's operation - not coherence. Coherence is irrelevant for hobbyist purposes (besides holography I suppose).

More about coherence.

Article on laser in nature
 
Those links were a good read. I didn't understand the math stuff though. Thanks guys.

Michael.
 
I didnt read all, Im in the laser optics field, and it does indeed occur in nature. Its called random lasing, and we also try to do it with randomly deposited nanoparticles in thin film layers. This makes a cavity a non necessary thing for a laser.

There are stars that do this all the time, and due to their huge size if you have a photon that starts in the middle of the star, at the star surface u get a quite powerful laser.

Ill try to find a few papers on it and I'll edit this post with a link to them.

*EDIT*
Here is a quite good article in Nature, after they published a paper on random lasing:
http://www.nature.com/nphys/journal/v9/n6/full/nphys2635.html?WT.ec_id=NPHYS-201306

It has several references that you can follow to find more about it (like they said, in mars, stellar gases and other stars)



*2nd EDIT*
I noticed that you asked if lasers are the only coherent light sources. Actually any light source can be made coherent with selectiveness. After you pass the light from a normal lamp through a slit, the light coming out of the slit is spatially coherent, meaning you can perform interferometric experiments. Think it like this, in the beginning of the 20th century there were lots of experiments using coherent light (interferometers) to measure the light speed, the ether, and many other things. They used, most of the times, candles or rude incandescent light bulbs. With the invention of the laser it was just possible to start having sources with higher and higher coherence, both in the time and spatial domain

better article on wikipedia on coherence (all sources, not only electromagnetic): Coherence in Physics

4th edit xD : Most proeminent naturally occuring coherent light is the light from stars. We are so far away that the light that reaches us has a very high spatial coherence, even for several hundreds of meters apart. I cant remember quite well now, but it was with a kind of interferometer that was several meters apart, getting star light (even before the invention of the laser) that they measured the distance of the earth to a star or its radius or one of this astronomically huge distances.
 
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LordKaramazov said:
There are stars that do this all the time, and due to their huge size if you have a photon that starts in the middle of the star, at the star surface u get a quite powerful laser.
Click to expand...

Stimulated emission requires electron energy level transitions. How can you have electron energy level transitions when the gas is ionized and has no electrons associated with it?
 
Cyparagon said:
Stimulated emission requires electron energy level transitions. How can you have electron energy level transitions when the gas is ionized and has no electrons associated with it?
Click to expand...

You are right...When i posted the first time i was writing without thinking. Like the article said, this happens in stellar gases. But even in a star, you have a quite dense plasma, but it does not mean that you do not have neutral atoms. Actually there are lots of neutral atoms.

A simple experiment to actually prove this is the really old light and grating experiment from the sun light. How did they discover what stars are made of? From Hidrogen and Helium lines being emmited from the stars. Well you can think that your HeNe laser tube is also a plasma, but it still emits light like its made of normal neutral atoms/molecules.

I think I am not missing something now, or should i consider more things?? :thinking:

*EDIT*
And not only electron level transitions. Molecular vibrational and rotational levels are also able to lase. Thats how masers are made. It has to be an energy transition of the atom/molecule, not necessarily from an electronic level.
 
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LordKaramazov said:
HeNe laser tube is also a plasma
Click to expand...

Different levels of ionization. The hydrogen in the sun also only has one electron to loose, while the helium has two and the neon has 10. Besides, I'm not aware of any "HeH" lasing medium.
 
Wow.. Nicely said! if i was a cosmologist, i might have been able to convey something similar... haha

What you described could be classified as a natural occurring (and somewhat crude) gas laser, couldn't it? If those ionized photons had means of a lens (crystal, raindrop, dew, mist etc) to focus a beam, I see it being perfectly plausible for a naturally occurring laser.. Radiation is emitted everywhere in "nature" and if we think to what the acronym of L-A-S-E-R stands for... The question essentially answers itself, I'd say.


Serious note- As far as nature and lasers go.. I personally like to romp around the house "naturally" sniping balloons and unsuspecting jewel-case backings :crackup:

Speaking of.. Anyone need blank cd's? I've got a few thousand.. No cases, though :beer:
RA_pierce said:
Lots of high energy photons are spewed out of young stars, black holes, and other stellar objects which ionize nearby gas clouds.
This matter will emit radiation either as heat or light.
Auroras are not unique to Earth. High energy particles create light in the ionosphere.
So light is produced in many different ways on Earth and in space...

But I don't know if stimulated emission like what we get from lasers can be done without an artificial apparatus. I suppose coherence would be the determining factor that separates other sources of light from "laser" light.
Although nature does all kinds of crazy things so I wouldn't be too surprised...
Click to expand...
 
Cyparagon said:
Different levels of ionization. The hydrogen in the sun also only has one electron to loose, while the helium has two and the neon has 10. Besides, I'm not aware of any "HeH" lasing medium.
Click to expand...

I did not mean to state, that stars make this natural lasers (I corrected after your observation...i do not know-also didnt search for-of scientific evidence of laser light out of a star. When i wrote my first post (i guess i should edit it) i was thinking of stellar gases, and the Nature article, i had confused both).

The thing is, in your HeNe, its not the ionized molecules that take part in the lasing action. And perhaps thats where my explanation was poor. A plasma is a quantity of gas, that is partially or almost totally ionized, that is able to conduct current but still keep its neutrality overall.

The normal plasmas in your gas lamp, and HeNe tubes are mainly constituted of neutral molecules in the normal ground state. The current comes from the few molecules that ionize and give electrons to the medium. In stars however theres a big percentage of ionized atoms. So there are atoms that can be in an excited state in a star (and still have every electron) and be able to lase. Just dont know if the reabsorption would be much stronger to kill any laser action in a long path.

All i meant with my last post is that it is completely plausible to have a "star laser" when considering some parameters. But as you need a population inversion (which i believe is easy to achieve in a star) and a low absorption of the lasing wavelength (this is where, now, i think a star laser wouldnt happen. Specially due to star density), perhaps its quite hard. At least without a feedback.

And a HeH laser medium, most probably would be able to lase. At which wavelength, I do not know. But some 3-level or 4-level would be feasible, for sure. Just might not be even worth trying it xD
 
Cyparagon said:
So it takes schfifteenteen point five and a half third moles to equal one plasma, right?
Or maybe it's just "quality over quantity," as they say ;)
Click to expand...

Thats about right, when you consider the grand approximation. Even more accurate is the introduction of the nailed it correction which is:
schfifteenteen point five and half third MINUS the number that also represents the weight of a new-born snail(of the Helix aspersa species), at exactly 10min,37secs, in µg. But the exact quantity perhaps will never be known to mankind. :D
 
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