Lasers Visually Explained

[@Higgsinophysics]

Prefer to read? Here is my article about lasers: medium.com/@Higgsino/the-surprisingly-simple-physics-of-a-laser-47d7d23e928e Physics Teacher would probably be mad I didn't cover Laser Resonator Modes and the nice property of using 4 level atoms. But nevertheless I hope you learned something new :) - Special thanks to "Pretty Much Physics", "Zap Physics", "Ancient Accounts" and "everything science" for correcting this video. - Thank you to the nice folks over at p5py for making an amazing python animation package. - Thank you to the wonderful patreons

[@muhammadshaban9368]

why laser use pump source flash light why not use countine light please tell me.

[@KendnanGalvãoMacêdo]

bote um espelho um de frente para do outro o vc um lunpin infinito da mesma imagem como vcs chamam de viagem no tempo

[@KendnanGalvãoMacêdo]

no espelho 🪞 tempo anda Patras o movimento pra frente

[@zapphysics]

I can't get over how great the animation at 10:50 is. Excellent job showing this in action! Great job, man!

[@AncientAccounts]

"most important tool for teasing cats" lmao

[@noelomaolchraoibhe3911]

FWIW, you are the first subject matter expert I have found that was able to explain stimulated emission in a way that made it comprehensible! I have watched many videos that purported to explain the phenomenon and all failed to get it across to me. Your script & visuals are just right.

[@ParthGChannel]

Ahh so clear, so crisp. Loving it my dude!

[@companyjoe]

Thank you! I did have to pause and rewind constantly but after all this video explained lasers better than any other video I've seen.

[@Higgsinophysics]

glad you liked it! Thanks

[@williamfitzsimmons2154]

Before I ask my question, I just want to say this channel is a diamond in the rough. Your ability to create simplified, truncated visual simulations, will take you far in the youtube physics educator space. Additionally, the way you guide the viewer through an iterative design process of why each part of the laser is there is severely lacking in this space and will give you a huge edge. My question is, how critical is the allignment of the mirrors of the laser? I would guess that without perfectly alligned mirrors, the photons would inch their way across to the side after every reflection, ruining the effect. Just a little feedback, I would refrain from simultaneously explaining an effect while showing the effect. It can be a little overwhelming. I think an explain-then-show pace may be more effective. I've only just discovered this channel, so maybe this has already been addressed.

[@minerscale]

What an awesome video! Beautiful looking, clear and consice, incredibly educational. Thanks for making top quality videos!

[@rajiv8k]

Thanks, If only I had these resources when I was a kid... Our teachers never explained it to us like this.

[@PrettyMuchPhysics]

Great animations, as always!

[@alfredfeldt5694]

cool, random guy on the internet tells me what my physics teacher could not

[@aaron22372]

Thank you for an informative video! I don't fully understand why the light coming out of a laser is coherent. "Stimulated emission" explains why an initial photon bouncing back-and-forth can accumulate a large number of coherent photons. But it seems like there would be countless "initial photons" all over the cavity, each accumulating their own, independent collections of photons. Why would the phase of any one group match other groups?

[@xavierlebeuf3061]

I've always wondered how laser worked. And you explained it very well, thank you!

[@NoOne-mx4nx]

Thank you Sebastian Vettel for this amazing video.

[@quahntasy]

*Such an amazing simulation. I loved it.*

[@2false637]

I learnt something cool today thanks to you! Great content.

[@pranitabaruah266]

Why when the optical cavity gets pumped by the optical pump only half of the atoms get excited? I mean yes, when half of the atoms are excited and optical pump lights up again then the already excited atoms undergo stimulated emission and get de-excited and the relaxed atoms get excited and so again only half of the atoms are excited each time and the cycle continues (this is true only if the atom has two energy levels). But, why only half of the atoms are excited in the first place? Why when the optical cavity is first blasted by light from the optical pump only half of the atoms are excited? Why don't all of them get excited in the first place?

[@Higgsinophysics]

That's a brilliant question. Keep in mind this is just a simulation. But the real world is complicated. I could write many problems, but one big problem is, if you wanted all the atoms excited by one blast the intensity of the photons would be extreme!! And it is not possible to let photons arrive at exactly the same time, photons follow a Gaussian distribution. So if one atom gets excited by the very intensive blast, then a nanosecond after a slight delayed photon would de-excite it. Or the blast could be so powerful it excites other electrons in the atom or ionize the atom

[@pranitabaruah266]

Oh My God! You actually replied! I am your big fan Higgsino Physics! I LOVE all of your videos and your laser video, in my opinion, is the only video on KZbin that actually explains how it works easily because of the animations. Your animations are phenomenal and they make understanding physics so easy! Your video in which you used dominos to explain sound propagation blew my mind! Your videos have been so helpful to me in Physics. Higgsino Physics, I actually don't have good physics teachers or any people to whom I can ask my physics doubts and so I have to self-study physics and I have an entire document full of doubts in physics. Could you please help me in physics by some means (for e.g. so that I can easily ask you various physics questions if I have doubts in them)? It would mean the world to me if you could help. THANK YOU SO MUCH!

[@Higgsinophysics]

Glad to hear you like and learn from my videos! Thanks man. I think you could get much better and faster answers on physics.stackexchange.com/ :)

[@pranitabaruah266]

I know this might be a stretch but is there any way through which I can contact you Higgsino Physics for asking nothing other than the doubts I have in physics?

[@pranitabaruah266]

kzbin.info/www/bejne/op6Wc61ohMpqirM The above video is my attempt to explain why is the sky blue in colour. I know it isn't good. I just want to share it with you Higgsino Physics.

[@ashutoshsethi6150]

Why does the new photon has same phase and frequency and polarisation as the incodent light, why does it not undergo randomness like the phosphorescence atom?

[@ItsMe-rp6rf]

Hey ..plz tell me the background music... 10:15 to end

[@harshvardhan4771]

2:55 I want to ask if I have understood it correctly. Lets take a hill, with a rounded top, and there's a ball about to roll down. By the top being rounded, I meant that there is a very narrow spot, where if the ball is placed very carefully (with zero velocity), it stays, or else it rolls down, or in other words, an unstable equilibrium. So for spontaneous emission, it is like- when downhill, we gave the ball just enough velocity for it to reach the top and then just a teensy bit further. So, it will eventually fall off on the other side, but it will be taking a very long time. By analogy, we made the electron to jump from ground state to a excited state, by giving it a precise frequency of radiation, which it will lose after some time, giving out the same frequency of light. Now for Stimulated Emission- it is the same for making it go uphill, but then, instead of waiting for it to slide off the other side, we give it a little nudge, to make it happen faster. And since it was just a small nudge, it doesn't have much of an effect on its velocity when it reaches the bottom, but it does happen earlier than without the nudge. So in the analogy, the frequency of light emitted back is still the same, but it happens earlier than spontaneous emission. Now I have some questions, which relate to both, the actual laser and the analogy used here- 1. Why does the radiation which stimulates the emission (the nudge on the ball) have to be of the same frequency? 2. However small, how does the nudge not change the final velocity of the ball, or analogously, why does the electron not absorb the ray used for stimulation too, get even more excited, and then emit an even higher frequency? Or is it that this *does* happen and I just described Second Harmonic Generation in Non-Linear Optics?

[@alexwang007]

Would you consider diving into other laser topics such as modes, mode locking, and q-switching?

[@Dasher_The_Viral]

Definitely subscribing!

[@pratyushpathania7030]

just freaking amazing !!

[@adonaythegreat8426]

Easy to understand.

[@AndresTorres3d]

I have a question... where is the laser coming out? i mean, I see the photons bouncing, but when and where do they come out of the cavity?

[@burada8993]

Thanks. In the next step, how are these laser emissions are taken out from the optical cavity?

[@soumyaranjannayak3554]

One of the mirrors is allowed to transmit some of the light, instead of being close to perfectly reflective.

[@marcovillalobos5177]

YOU ARE AWESOMEEE

[@ferguscooper2266]

That was a great video!

[@pankajkulkarni6722]

Great video!

[@joeyysossa4144]

I took apart a simple laser pointer when I put it back together it didnt work anymore...what went wrong???

[@Chandlerd17]

Nice but it seems like everyones explanation is a bit ambiguous around the pot so to speak and very simplistic,i would like to know the math and energy it takes to operate a laser and its output energy and its losses.this information seems very obscure because there is no video about it,not even MIT.what’s up with that?i would love to hear a clear explanation of the mathematical working principles.

[@goki6548]

That is what a ✨textbook✨is for. Or just search online. If you can not find any resources ask physics stack exchange for nice resources and they will provide you with many great sources

[@8dgrooves334]

Hey dude, I gotta say...This video is AWESOME ! ! ! can you please add subtitles?

[@marcovillalobos5177]

Is the code in GitHub? It would be really interesting to play around with the animations, and to change things to see how the system reacts

[@Higgsinophysics]

It's not available now... But i plan to make it (and other things) available in the future :)

[@marcovillalobos5177]

@@Higgsinophysics That's a shame, I've tried to make one of this myself but the stimulated emission part makes it really difficult to code

[@MultiSciGeek]

What's with the hippie band??

[@nupurbagwe1342]

you explained everything in less than 13 mins whereas my professor wasn't able to do in 4 lectures 🙂

[@KhagisaraPathak]

My professor told us to read it by ourselves. Didn't even bother to give 1 lecture on the topic.

[@ARCSTREAMS]

you are saying that an electron will absorb a red photon and will emit a red photon? that makes no sense ,from what i know the photon emitted by spontaneous emission will have a longer or weaker wavelength than that of the photon that created it ,this is why for example an 808nm photon will excite yag crystal to emit 1064nm photon, the 1064nm can stimulate other electrons already in the exited state to emit another 1064 photon but if 1064 hits an electron in ground state it will be either absorbed or passed as heat otherwise why not use 1064 diode to excite the yag instead of 808 diode?

[@ashutoshsethi6150]

That is fiurescence?

[@ashutoshsethi6150]

Fluorescence?

[@ARCSTREAMS]

@@ashutoshsethi6150 depends on the lasing medium but generally yes

[@muhammadshaban9368]

why laser use pump sorce flash light why not use countinue light

[@KendnanGalvãoMacêdo]

tente um teste com um espelho 🪞 leiser tente caucular velocidade muda trajetória da luz leiser

[@BorisNVM]

cool

[@diegoavalis3886]

4:48☠️☠️☠️☠️⚰️⚰️⚰️⚰️⚰️ flashlight

[@vinniepeterss]

❤❤

[@atticuswalker]

is this just a theory or the best sudgestion to date. there seems to be alot of conclusions based on what could be happening. or . the wavelength of light that enters the glass passes through to a space where the ruby crystal has a different effect on light than any other transparent mass. being red. so when the uv tries to get out the other side as a different wavelength. it can't.

[@itstommyv6895]

Are you ok?

[@KendnanGalvãoMacêdo]

pense no tempo como moeda joge para sina agora tentar prever cair 😮 ou coroa 👑 tanto faz o resultado tanto faz tempo os dois estão sertos um tempo no tempo cai 😮 ou 👑

[@kayrstar8965]

A comment

[@HandFromCoffin]

quantum mechanics = Magic just believe it, I can explain it but you'll only understand it less.. just accept what I say.

[@fightme5543]

quantum mechanics; If you can't think in 4 dimensions - don't try

[@capsul3s]

This is the worst explanation from you. I can't understand what you are saying. It's like you're reading off a textbook. 2nd half of the video with diagram and the explanation isn't too bad. Try summarising the concept. Cheers.

[@Higgsinophysics]

You need to be kind and polite when you talk to me

[@goki6548]

@@Higgsinophysicsyea ignore him i really like your stuff. I think the explanation is very nice

[@turbochicken80]

Are your videos trustworthy?

[@JeronimoStilton14]

No but they are worthy of trust

[@AndreaSproccati]

There’s something strange in n your voice or the editing of the audio that makes it very hard to understand what you are saying

[@requiem_exe]

skill issue

[@safwan6363]

Probably the gaps between his sentences are too short

[@fly8641]

if you cant understand his accent or words then maybe this isnt the type of video for you 😭

[@erner_wisal]

​@@fly8641It isn't anyone's fault. That's also why ho includes a written cc.

[@excellentmike]

I recommend you don't go into teaching. I found it very hard to follow compared to other videos on the same subject.

[@noelomaolchraoibhe3911]

And I found the exact opposite!