3-level System and 4-level system

[@azegeaustin5615]

Thanks, Prof., you have simplified the entire topic and made it easy for me to comprehend.

[@abdelrhmanyousif7657]

Thanks Prof., excellent lecture, I learn a lot from you.

[@simranatwal4324]

I m subscribing ....awesome explanation 😊😊😊😊😊

[@al-banna3076]

Waoooo.... Excellent lecture. Your method is v. Good. I understand v.well. Thanks sir

[@danielbarraganbarranco1837]

awesome explaining, thank you, Profesor

[@syedwaqar9809]

Kamal kr dia ❤️

[@rajeshpradhan9562]

4 level system has more efficient to produce laser than 3 level system thanks sir🙏🙏🙏🙏

[@ARCSTREAMS]

why

[@AnmolKumar-bi7wp]

@@ARCSTREAMS easy to maintain population inversion since the groundstate is not directly inverted

[@milindbhandare5555]

Very nice explain

[@jacobvandijk6525]

Of the emitted photons, triggered by spontaneous photons, only those survive with a direction perpendicular to the mirrors of the laser.

[@chinmay470]

Please suggest a book name for laser

[@sem1982s]

Like in three level system, can we pump continuously in two level laser system in order to get the population inversion

[@brijeshmehra8182]

Lifetime of level 2 is very very short
(in comparison to level 3 )
So, in case of two level system we can at most and at rarest can achieve N1=N2 condition. So population inversion is not possible in two level system (N1

[@060saurabhkumar8]

thank you sir for the lecture

[@shikhaphysics8970]

Thnq so much sir 🙏🙏🙏🙏... Great explanation

[@r.bhargavram3546]

Atom or electron which one is excited from lower energy level to higher energy level

[@perceivingscience138]

Me too the doubt, but convinced that when the electron of an atom is excited it is considered that the atom having that excited electron is also excited.

[@anesurrahaman7825]

Thank you sir
The answer of the last question is
4 level system is better than 3 level system

[@vimangasubasinhe5080]

Thank you sir. Its very helpful and very easy to understand.

[@shwetakamat7046]

Sir... Explanation is too good... Can I get derivation of these levels

[@VERSATILITY7]

super!!!

[@rishabhsingh3670]

The og professor

[@evanrutherfordlazyahole9079]

It's about the pump bro. Then I'm firing my laser.

[@lipichakraborty5139]

Thank you so much sir for such a beautiful explanation... Sir i can't understand quantum field theory... Can you please make videos on qft.. It'll be very much helpful for me

[@Hamzakhan-fz2oj]

thank you

[@akashshukla9702]

Thank you professor

[@HiddenAges]

off-course 4 level laser system will be an efficient system. Because even if we are able to pump one atom we can have population inversion between level 3 and 4 which is the condition for laser action and this is not possible in 3 level system...

[@sreemayakp2814]

Sir, is 4th state in a 4 level system a metastable state? If yes, why does it undergo very fast non radiative decay?

[@anesurrahaman7825]

Calculation of these levels can you provide sir ?
Sir pls

[@riteshdas5107]

Sir, reason behind fast decay or nonradiative decay

[@ayshathsharfeena342]

Thank you sir

[@mzzaka_009]

Thanks Sir, Very excellent lecture but it could not clear to me, how we will get continuous laser in four level system ?
Anyone please clear me in three level system laser will produce discontinuous manner but on the other hand it will be continuous in case of four level system.

[@brijeshmehra8182]

There will always be more no. Of electron's in level 3 in comparison to level 4. As lifetime of 3 is more than 4.
We get continuous pulse as there is no delay which was in the case of 3 level system.

[@manotosh3145]

Thanks sir

[@mahibabu6789]

If the spontaneous emission triggers the stimulated emission but spontaneous emission is not coherent then how the stimulated emission will become coherent?
Thank you

[@himanshuful]

When we say spontaneous emission is non-coherent, we meant that group of photons which are in output have different frequency, phase, direction. But here 1 spontaneous photon or very first emitted photon acts as external photon and all others photon after this trigger will have same frequency, phase & polarization as these 1st emitted photon.

[@nishasinghchauhan6395]

4 level system can work better and more efficiently than 3 level laser because the 4 level laser have less lifetime in higher state

[@playingwithdata3904]

kotha khologe??

[@evanrutherfordlazyahole9079]

Not like I understand this stuff.