LASER: Surprisingly simple physics | Simulated
ฝัง
- เผยแพร่เมื่อ 24 ก.ค. 2024
- The physics of a laser - how it works. How the atom interacts with light. I’ll use this knowledge to simulate a working laser. We will learn how LASERs relies on Stimulated absorption, Spontaneous emission, and most importantly: Stimulated Emission- This last type interacts with an excited atom, causing it to relax/deexcite. It will send out a photon with the same phase, frequency, polarization and direction. We exploit this principle in a optical cavity, with the atom as a gain medium.
It turns out the pump will cause stimulated emission for the wrong excited state and we need to use a 3 level atom in order to obtain population inversion.
I'll also cover meta-stable state, phosphorescence, radiationless transitions and photoluminescence.
Help me produce more physics /science content here
/ higgsino
Longer simulation video:
• Working laser simulation
0:00 - Introduction
0:18 - 1.1: Atom and light interaction
1:53 - 1.2: Phosphorescence
2:40 - 1.3: Stimulated emission
4:10 - 2.1: The Optical cavity
5:19 - 2.2: Overall plan for LASER
6:20 - 2.3: Population inversion problem
7:43 - 3.1: The 3 level atom
8:18 - 3.2: Photoluminescence
9:03 - 3.3 Radiationless transitions
10:25 - 4.1: A working LASER
11:44 - 4.2: Coherent monochromatic photons
12:14 - 4.3: I hope you liked it!
![ลักพาตัว เอาลูกเอิร์นกลับมา...!! [เอิร์นไดเม่]](http://i.ytimg.com/vi/f4NVKlZ5qkk/mqdefault.jpg)
![How Does a Laser Work? Quantum Nature of Light - [3]](/img/n.gif)
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
why laser use pump source flash light why not use countine light please tell me.
bote um espelho um de frente para do outro o vc um lunpin infinito da mesma imagem como vcs chamam de viagem no tempo
no espelho 🪞 tempo anda Patras o movimento pra frente
"most important tool for teasing cats" lmao
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.
Ahh so clear, so crisp. Loving it my dude!
I can't get over how great the animation at 10:50 is. Excellent job showing this in action! Great job, man!
What an awesome video! Beautiful looking, clear and consice, incredibly educational. Thanks for making top quality videos!
*Such an amazing simulation. I loved it.*
I've always wondered how laser worked. And you explained it very well, thank you!
I learnt something cool today thanks to you! Great content.
Great animations, as always!
Thanks, If only I had these resources when I was a kid... Our teachers never explained it to us like this.
That was a great video!
Easy to understand.
cool, random guy on the internet tells me what my physics teacher could not
YOU ARE AWESOMEEE
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?
Hey ..plz tell me the background music...
10:15 to end
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.
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.
Thank you Sebastian Vettel for this amazing video.
I took apart a simple laser pointer when I put it back together it didnt work anymore...what went wrong???
cool
❤❤
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
It's not available now... But i plan to make it (and other things) available in the future :)
@@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
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?
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
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 TH-cam 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!
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/ :)
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?
th-cam.com/video/lm3Bz2Oe7TQ/w-d-xo.html
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.
tente um teste com um espelho 🪞 leiser tente caucular velocidade muda trajetória da luz leiser
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?
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 👑
Hey dude, I gotta say...This video is
AWESOME ! ! !
can you please add subtitles?
why laser use pump sorce flash light why not use countinue light
you explained everything in less than 13 mins whereas my professor wasn't able to do in 4 lectures 🙂
My professor told us to read it by ourselves. Didn't even bother to give 1 lecture on the topic.
A comment
Are your videos trustworthy?
I recommend you don't go into teaching. I found it very hard to follow compared to other videos on the same subject.
And I found the exact opposite!