How LASERs work! (Animation with Einstein)

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The stimulated emission of light was a discovery by Einstein around 1916. All we need is an atom, which possesses electrons just like any other atom in our world and a photon, that is: a quantum of light.
Contents
1) Energy levels of atoms and electrons
2) Absorbing energy in the form of photons
3) Stimulated and spontaneous emission
4) Photons with same phase, frequency, polarization, direction
5) Parts of a LASER device (reflectors, gain medium)
6) Chain reaction for coherent and monochromatic light
7) Population inversion (ground state vs. excited state)

[@prabhjot9913]

Great explanation in just 5 mins. Precise, to the point and hats off to animations...

[@shalutfi]

well done. nicely explained...realy helpfull for students who have bad teachers......

[@feynmanschwingere_mc2270]

Here's the thing, Einstein did SOOOOOOOO much more than just Special Relativity and General Relativity. 1. He developed the fundamental theoretical basis for the LASER in a trilogy of incredible papers around 1917 (some of the most seminal papers in the history of science): On Spontaneous and Stimulated Emission, which predicted the LASER and gave us what are now known as the Einstein Coefficients. Einstein was the first person to quantize the radiation field, he created condensed matter physics (a whole field of physics), he created statistical mechanics and thermodynamics from scratch before 26, and he was ridiculed for 20 years for believing light was quantized. He essentially created both quantum mechanics and General Relativity (as Schrodinger always acknowledged privately). Einstein was the first to predict quantum entanglement in his famous EPR paper, a paper that wasn't properly understood for decades. Einstein was the first to integrate, even provisionally, quantum mechanics with chaos theory. Einstein was the first to show that atoms and molecules exist and to accurately describe their size. Even with Special Relativity, there was interpretational confusion for years even after 1905. Poincare AND Lorentz both famously thought Einsteins Special Relativity paper was WRONG (for very sophisticated reasons). This is ironic because they, along with Maxwell and Fitzgerald, contributed the most to the pre-Einstein formulation of Special Relativity. Einstein crucially showed how the conservation of energy theorem must be a direct consequence of SR, that was a step that might have take years to achieve. Einstein was also the first person to predict the Boson (should have been named the Einsteinion but due to an odd moment in history it was incorrectly named). He was the first to predict the 5th state of matter now termed Bose-Einstein Condensates, crucial for superconductivity. He invented several branches of physics (e.g. relativistic kinematic, physical chemistry with his paper on brownian motion, statistical mechanics, solid state physics, etc). If Einstein had never lived we dont get GR for 100 years and even if we got it, it probably wouldn't be in its current form. It's impossible to know of anybody would've filled in the void, but I doubt anybody could replace Einstein. He was a once every 300 years sort of mind. He solved the Tea Leaf Paradox in his spare time, a puzzle that had vexed thinkers for centuries. Einstein also achieved something that perplexed the great Isaac Newton until the day he died: he explained WHY gravity obeys an inverse square law. According to head of applied physics at Yale University Douglas Stone, Einstein should have won 10 Nobel Prizes - and would have won 10 Nobel Prizes had his achievements been done by 10 separate physicists. Several other science historians have echoed the same sentiments. He's the greatest scientific mind of all time. The Equivalence Principle was staring every human who has ever lived right in the face, but it took Einstein to make that discovery in 1909. Only in hindsight is it obvious. Let that sink in.

[@rockysharma5637]

thanks it helped me a lot ....... best explanation so far i have seen

[@autopy9866]

We need an animation like this to understand the concept behind lasers.I wonder how difficult was it for einstein to understand this concept.Huge respect for him.

[@tootsykablooie6067]

I've been through tons of videos, and finally a good explanation! Great video!

[@karankanojiya8197]

you clarify it very easily.I am impress

[@nithyasreeselvakumar6758]

That's extremely a grt animation..loved it..hats off..Looking forward to more videos...

[@himanshupant430]

Best video for explaining!!

[@liweiwang6345]

Really appreciate your work! It gives me a better explanation than 2D diagram!

[@EngineeringEssentials_CTEVT]

I'm a student in grade12...this video made easy to understand laser..thanks man

[@SiddhantNagpal]

This makes it so clear, thank you so much!

[@SaurabhGupta_Mentor]

Finally,after coming in BTech now i understand the working principle of LASER clearly. Thank you sir for such great video.

[@kedarjani4396]

U Graduated, Congratulations 😅😁😁

[@doggybag71]

5:00 - I'm not gonna lie, this is definitely me when I'm a stimulated emission of light aggregated in a gain medium and then released as a highly collimated beam.

[@ahmetkarakaya217]

Great explanation with a great animation. Very high quality job..

[@kishorebalagurunathan8530]

best video ever seen about working of lasers

[@augustineraj3662]

grea8 video sir. such complicated physics explained in just 5 min!!!!!

[@songs-pu9bq]

This is the best educational animation i have ever seen👍👍

[@ardonjr]

Best explanation yet! Good video!

[@harshinieggoni2105]

nice,it's clarified our doubts thank u so much

[@abdulrahmandowaydri120]

Thank you for this amazing clarification :D.

[@shabeershabeer713]

I take my hat off. You have nailed it...............

[@sylwesterszymanski4051]

Great idea! Great work!

[@chandrashekark4234]

WOW, That's a Great Explanation.

[@NikhilBanka29]

This was so helpful. Thank you :)

[@aishwaryaalur6049]

Fabulous explanation

[@abhimanyuswati]

thanks, it was very interesting and easy to understand

[@jesussaves6671]

very good explanation

[@Sek89si29]

You deserve more subscribers. Amazing work.By the way what 3D software do you use for making these videos?

[@ThomasSchwenke-knowledge]

Hi, I use Carrara 8 Pro. It's a great tool :)

[@SACHINMANGALBIT]

more then expected great....................thanx

[@anakinslucien7193]

This is amazing, better than Wiki anyway. Thanks!

[@curiouschemist7184]

Hats off the animation power....gajab🤟🤟👏

[@werter1910]

At 3:33 the electron that goes to E1 still emits a photon right ? Just not with the same frequency as the incident photons from the pumping laser, but the electron energy has to go somewhere

[@komaleducation9620]

Bestest and only one video which clear my all doubts regarding laser 🤩🤩

[@ali-ej8km]

Best explanation ever!

[@drxguddusagar365]

I have seen many videos on KZbin but your video is very fantastic . I am from India . Thank you so much.

[@sarax9101]

Great video!!

[@chemy7112]

Helpful

[@adityadeshmukh4076]

Very helpful

[@kardoabas7642]

Thank you so much

[@bhavyasinghal2790]

best video avilable!!! amazing but make more videos plz

[@kunjalvekhande9111]

Awesome work guyzzz

[@jiwu9162]

Well done!

[@husnainbhatti9778]

Excellent video!!! Would u plz explain helium -neon laser working by the same method... That's really kind of u...!

[@AiswaryaM739]

Very informative.

[@chrvoje_engineering]

Thumbs up for Animation at beginning with Einstein, In what software you made this

[@ThomasSchwenke-knowledge]

Carrara 8.5 Pro

[@nishanks93]

As RealationGames asked, why does the transition from E2 to E1 not result in the emission of a photon?

[@wipos4636]

There's more to add, about metastable state and its lifetime. I think its important

[@BADGAYAN]

You know lots of physics stuff thank you

[@jaimeemorgan9984]

Brilliant. I love it!

[@pankajjadhav0]

best video avilable!!! amazing

[@djokcnnn]

Amazing

[@okamiamadeus5163]

This is better, i can review the video and fully understand it in the end. Unlike some videos no matter how many times i did it, i still can't understand all of it.

[@prasadbr9660]

Hats off explanation.

[@josephherndz8289]

wow! this was great

[@IkramKhan-br1es]

thank you...amazing...

[@engrmohamedgad5647]

well done

[@zalakshah3499]

awesome video...very nice explaination...

[@scientificsue]

Fantastic!

[@vathsasri5628]

how can electron jump from E2 to E1 without emitting a photon,let's assume that it didn't emit a photon if we pass another photon onto it then it should get into a higher energy level but you say that it gives out two photons of same frequency.Can you be more specific about how it happens?

[@Mimimumumo]

it emits energy but not photon. its called non radiative emission. simply put the energy emited is not enough to create photon

[@grzesiekdomeyko]

Atom may switch to the state with lower energy in collision with different atom. The excitation energy is changed into kinematic energy and no photon emission is necessary. However, isolated atom may lose energy only via photon emission.

[@abdullahismail2770]

This transition result in heat loss to the inner walls of the tube

[@shahzaibhassan6504]

Well i had same problem, & i think this is the solution, Let's assume you provided 2 Units of energy (PHOTON) to the electron to send it from E0 to E1, this energy was equal to the energy difference between E1 and E0, so electron transitioned, now when again you provide 2 Units of energy which is equal to the energy provided previously, electron will have 4 Units of energy, which is higher than the requirement of E1 and lower than requirement of E2, so bcz of a bit disturbance it loses the previously available 2 Units energy too, which now also has a twin 2 Unit energy photon... So, answer to question that why it didn't go to E2 is, may be orbits do not have equal difference in energy level, like 2,4,6...so on, but rather 2,6,12...so on... I hope it will help you..

[@PhysicsMath]

1 is original another is transition energy

[@somsuvragupta3025]

thank you very very much sir

[@rockingvirdi96]

Great Work ! really :D

[@oanhoan4856]

Thank for your great video

[@makermax2013]

great video! : )

[@umairgul5983]

very informative and easyyy

[@herdsire90210]

I need this for target ranging my ion canon.

[@nawazkhokhar7726]

thanku

[@josefruzicka9637]

So the photons released from the semi-transparent mirror are those, which we can see then like a laser beam outside?

[@anugupta4544]

When a photon strikes the electron why does it comes to the lower level but does not go in above level in stimulated emission

[@nethmaprabhashwari4248]

Thank you for the great video But how does it divided into two

[@hemabandaru4737]

Simplyy amazing...........

[@scottboyce4058]

I have a laser that has 5 solder points on it, I've never seen on like this, although it's a class 1 laser I can figure out how to make it work. I don't want to burn it out trying to figure how to make it work is it possible to get help figuring this thing out ? I can't figure out how to send a pic on this system. The laser did come out of a Sony DVD/cd-r/rw, it has a square backing with the lense offset slightly gold in color with the 5 solder points on the back of the square

[@ravijha2322]

you are a Savior... thanks for making it understandable in such a short duration.....

[@kendo512]

What keeps the gain medium in a higher state than its ground state?

[@ricnyc2759]

What part of the atom absorbs the photon? The electron of the nucleus?

[@harishs7384]

Tq fr the video

[@AnkitKumar-pk8tk]

Can metastable state exist before excitation of electron

[@alvgomez4431]

excellent

[@ThomasSchwenke-knowledge]

Alv Gomez Thanks alot!

[@prateekchaudhary8188]

Why no photons are released when it transmit from E3 to E2?

[@allaboutourworld]

amazingly explained :) (y)

[@RealationGames]

Great video, definitely the best I've seen. I wonder why the E2 > E1 energy level drop doesn't emit anything. Where does the energy go? Is the emitted photon that is released in the last stage then more energized than one using only 1 drop?

[@ThomasSchwenke-knowledge]

For example through another electron. This is not possible for hydrogen (of course), but if there are other electrons in the atom, they can leave the atom.

[@MilanKarakas]

E2 -> E1 energy level (as well as other nonradiative decays in four level systems) actuall is called "nonradiative decay", which is not entirelly correct. It actually radiate long wave radioation which does not penetrate through host media, but instead contribute to its heating (or better said - overheating). If one atom or molecule has such long wave radioation, neighbour atom or molecule absorb it and convert to heat by random motion. It is too complicated to explain in such brief post, or short video.

[@iosef3337]

What gain medium lasers use??

[@ricnyc2759]

Why it doesn't get too hot and melts the ruby rod etc?

[@gabrielebellocchi8123]

Is it possible to use during an free exhibition in occasion ofthe year of the light?

[@jignareshamwala3401]

I had a question? Why can't a source that can excite the atoms or molecules to energy level E1 only serve the purpose.. Even in the illustrated case the stimulated emission is taking place from energy level E1.. What is the use of using two higher energy levels E1 and E2?

[@shubhamagarwal5426]

Dude in video it is done just to explain what stimulated emission actually is... Where in reality (basics) the rate of excitation and de-excitation(more precisely in thermal equilibrium) in a two level system is nearly same hence there would be no effective population inversion kinda thing hence no stimulated emission. P.S. I am no expert on this so don't go by this explanation in your exams i can't assure it is correct or complete.

[@younuskhan7274]

nice

[@kidsmoviesone1824]

What program you use for making this animations ? Thanks

[@ThomasSchwenke-knowledge]

Carrara 8 Pro.

[@andrejrockshox]

there's no gravity in einstein's lab

[@drawforge9640]

Quite ironic

[@feynmanschwingere_mc2270]

Here's the thing, Einstein did SOOOOOOOO much more than just Special Relativity and General Relativity. 1. He developed the fundamental theoretical basis for the LASER in a trilogy of incredible papers around 1917 (some of the most seminal papers in the history of science): On Spontaneous and Stimulated Emission, which predicted the LASER and gave us what are now known as the Einstein Coefficients. Einstein was the first person to quantize the radiation field, he created condensed matter physics (a whole field of physics), he created statistical mechanics and thermodynamics from scratch before 26, and he was ridiculed for 20 years for believing light was quantized. He essentially created both quantum mechanics and General Relativity (as Schrodinger always acknowledged privately). Einstein was the first to predict quantum entanglement in his famous EPR paper, a paper that wasn't properly understood for decades. Einstein was the first to integrate, even provisionally, quantum mechanics with chaos theory. Einstein was the first to show that atoms and molecules exist and to accurately describe their size. Even with Special Relativity, there was interpretational confusion for years even after 1905. Poincare AND Lorentz both famously thought Einsteins Special Relativity paper was WRONG (for very sophisticated reasons). This is ironic because they, along with Maxwell and Fitzgerald, contributed the most to the pre-Einstein formulation of Special Relativity. Einstein crucially showed how the conservation of energy theorem must be a direct consequence of SR, that was a step that might have take years to achieve. Einstein was also the first person to predict the Boson (should have been named the Einsteinion but due to an odd moment in history it was incorrectly named). He was the first to predict the 5th state of matter now termed Bose-Einstein Condensates, crucial for superconductivity. He invented several branches of physics (e.g. relativistic kinematic, physical chemistry with his paper on brownian motion, statistical mechanics, solid state physics, etc). If Einstein had never lived we dont get GR for 100 years and even if we got it, it probably wouldn't be in its current form. It's impossible to know of anybody would've filled in the void, but I doubt anybody could replace Einstein. He was a once every 300 years sort of mind. He solved the Tea Leaf Paradox in his spare time, a puzzle that had vexed thinkers for centuries. Einstein also achieved something that perplexed the great Isaac Newton until the day he died: he explained WHY gravity obeys an inverse square law. According to head of applied physics at Yale University Douglas Stone, Einstein should have won 10 Nobel Prizes - and would have won 10 Nobel Prizes had his achievements been done by 10 separate physicists. Several other science historians have echoed the same sentiments. He's the greatest scientific mind of all time. The Equivalence Principle was staring every human who has ever lived right in the face, but it took Einstein to make that discovery in 1909. Only in hindsight is it obvious. Let that sink in.

[@andrejrockshox]

@@feynmanschwingere_mc2270 hope you put that as your own comment too, not just as a reply to my comment.

[@adrienmau8082]

Hello ! I've seen many of your videos and you are doing a great job :) , I'm currently bulding an app to teach young people about light and optic, and I wonder... would it be possible to use this video about laser? (I must say i'm jealous of this Einstein's animation ...). The app will be free, of course. Thank you :)

[@ThomasSchwenke-knowledge]

+Adrien Mau Hi, thank you. No, currently this is not possible.

[@adrienmau8082]

+Thomas Schwenke No problem, i can understand. Keep up the good work :) !

[@dfgfhg]

Why do the two electrons exit the atom in the same direction ? And why in the direction of the hitting electron ?

[@itsiwhatitsi]

Not electrons but photons are the particle that you are talking about

[@aneyesky]

excellent ,although it still baffles my brain. the illustrations help.

[@amruthavarshini5833]

You are saying that no photon is emitting from E2 to E1, so energy from E1 to E0 be same as that of energy used for excitation...ie, in the output, we are getting the same energy (laser) as that of input... So what's the use of this laser concept?? I don't understand the concept clearly..!! Can you please tell me clearly

[@krishnavardhanreddypallerl9934]

Bro, can u plz upload something related electronics

[@thamizhanbant2390]

Hmm... firstly, HTML and JavaScript cannot be used to make animation. They are used just to impliment some functionality when you click on something or move your mouse pointer over an object. Animation can be created using Flash or using an...

[@musicgu7]

Hey! What program did you use for the animation? Thanks!

[@ThomasSchwenke-knowledge]

+musicgu7 Hi, I use Carrara 8 Pro for all for my animations.

[@musicgu7]

+Thomas Schwenke Thank you :) I had not heard of Carrara before but I'll check it out now! Love your videos, looking forward to more! Cheers!

[@aryakrishnab8361]

😊Nice video 🤗😍

[@user-vi3pi9rf7w]

how can an electrom descend I mean u r giving the energy by photon and what u get is excited state to ground state with total emission of two photons shouldn't it go up in level bcz of absorption of photon or it should just maintain its position ??? (stimulated emissions) why does it descends tell me, now u will say its bcz of population inversion then won't there be any photoelectric effect???? man I'm confused :(

[@dipeshsomvanshi4383]

Fabulous

[@ninpo14]

Scary to watch late at night..

[@ritiksharma.rs99]

Please get this video in Hindi also by the way it is very good