Four level laser system

[@PranayBalwant]

Great explanation 😀

[@bhakthidilshan9492]

how can we apply population inversion to E2, the it is not a metastable state?. the photons will not be there for long?

[@Akshay-s4j7x]

population inversion takes place between two energy levels, here that is E3 and E2 and E3 is the meta-stable state

[@dhamodharreddyguthikonda2260]

After emitting the stimulated emission then number of atoms in n3 decrease ,then how lasing action produces

[@EngineeringPhysicsbySanjiv]

For this pumping of atoms to E4 is continuously done so that more number of atoms can be available in E3 and lasing action continues.. Along with stimulated emission, number of atoms will fall down due to spontaneous emission as well.. So continuous pumping is required..

[@dhamodharreddyguthikonda2260]

@@EngineeringPhysicsbySanjiv thank you very much for clarifying my doubt

[@Cielo-sp7zy]

life time is more for E4 or E2??

[@EngineeringPhysicsbySanjiv]

Life time is more for E3 as E3 is a metastable state..

[@dhamodharreddyguthikonda2260]

Does it require high pumping of atoms to e4

[@EngineeringPhysicsbySanjiv]

Yes..

[@dhamodharreddyguthikonda2260]

@@EngineeringPhysicsbySanjiv thank you

[@gbalaji3593]

sir y sir u removed materials

[@EngineeringPhysicsbySanjiv]

Material is available in the description of the following videos..
Notes are also available in the decription of each video..
Module 1 : Diffraction Diffraction Playlist (All Video Sessions) : th-cam.com/play/PLQzUXa8lZVq_HKqpeG-UeZrFmDz1m0_SW.html
1. Diffraction Session 1 (Fraunhofer diffraction at a single slit)
th-cam.com/video/vpJ2KQud-4o/w-d-xo.html
2. Diffraction Session 2 (Fraunhofer diffraction at a double slit)
th-cam.com/video/o0dRzDSe98Q/w-d-xo.html
3. Diffraction Session 3 (Diffraction Grating)
th-cam.com/video/rGO1PHiv52M/w-d-xo.html
4. Diffraction Session 4 (Resolving Power of Grating)
th-cam.com/video/_tG1rz9fIQ4/w-d-xo.html
Module 2 : Lasers and Fibre Optics Lasers and Fibre Optics Playlist (All Video Sessions) :
th-cam.com/play/PLQzUXa8lZVq-tYb-kl0_1hU_ICJtXKj2J.html
th-cam.com/play/PLQzUXa8lZVq8ej59AUl6bk78kMGVsT5nS.html
1. LASERS Session 1 (Spontaneous Emission, Stimulated Emission, Light Amplification)
th-cam.com/video/wOyVaF-DG4A/w-d-xo.html
2. LASERS Session 2 (Nd:YAG laser, He-Ne Laser and Semiconductor Laser)
th-cam.com/video/eQGVkFBjGzE/w-d-xo.html
3. LASERS Session 3 (Einstein Relations and Applications of Laser)
th-cam.com/video/He-ygEP8ifo/w-d-xo.html
4. Fibre Optics
th-cam.com/video/ntTjTsiZ478/w-d-xo.html
Module 3 : Electrodynamics Electrodynamics Playlist (All Video Sessions) :
th-cam.com/play/PLQzUXa8lZVq97DPn9B7MlIm5CgTW6mMAc.html
1. Electrodynamics Session 1 (Scalar and Vector Fields)
th-cam.com/video/cWZSCK2UiZc/w-d-xo.html
2. Electrodynamics Session 2 (Gradient, Divergence and Curl)
th-cam.com/video/UsZHdfpQZkA/w-d-xo.html
3. Electrodynamics Session 3 (Maxwell Equations)
th-cam.com/video/Npr77Hg_Tmw/w-d-xo.html
Module 4 : A Special Theory of Relativity A Special Theory of Relativity Playlist (All Video Sessions) :
th-cam.com/play/PLQzUXa8lZVq-jogyawxwnE_JSt7IUArMy.html
1. A Special Theory of Relativity session 1 (Newtonian Mechanics, Inertial, Non inertial frames)
th-cam.com/video/5OFqIg2MhKY/w-d-xo.html
2. A Special Theory of Relativity session 2 (Galilean Transformations)
th-cam.com/video/HllZoEQrdcE/w-d-xo.html
3. A Special Theory of Relativity Session 3 Lorentz Transformations
th-cam.com/video/jkZltDQ3FRw/w-d-xo.html
4. A Special Theory of Relativity Session 4 (Time Dilation and Length Contraction)
th-cam.com/video/f6ANocR3LsU/w-d-xo.html
Module 5 : Nano Technology Nano Technology Playlist (All Video Sessions) : th-cam.com/play/PLQzUXa8lZVq9BBkINAGnGSBxOJOBGzbCq.html
1. Nano Technology Session 1 (Properties, Approaches, Methods to produce Nanomaterials)
th-cam.com/video/yPpMpHx6v4g/w-d-xo.html
2. Nano Technology Session 2 (SEM, TEM, AFM, Applications of Nanotechnology)
th-cam.com/video/kzcp8UNNM50/w-d-xo.html
Module 6 : Physics of Sensors Physics of Sensors Playlist (All Video Sessions) : th-cam.com/play/PLQzUXa8lZVq_IsVyzC3bKUlYV3K7nicwW.html
1. Physics of Sensors Session 1 (Resistive Sensor - PT100)
th-cam.com/video/WbeR0Ey3qPA/w-d-xo.html
2. Physics of Sensors Session 2 (Pressure Sensor - capacitive, flex and inductive)
th-cam.com/video/dFIk4nGEREg/w-d-xo.html
3. Physics of Sensors Session 3 (piezoelectric transducer - ultrasonic sound generation)
th-cam.com/video/kCbZW6b9FKc/w-d-xo.html
4. Physics of Sensors Session 4 (Optical Sensor and Pyroelectric Sensor)
th-cam.com/video/of3-ibcfrdk/w-d-xo.html

[@Cielo-sp7zy]

Life time will be most for E3

[@EngineeringPhysicsbySanjiv]

Yes.. E3 is the metastable state..

[@Cielo-sp7zy]

@@EngineeringPhysicsbySanjiv among E2 and E4 …pls answer

[@EngineeringPhysicsbySanjiv]

@@Cielo-sp7zy both these are not metastable states. So their life time will be of the order of 10^-8 seconds

[@Cielo-sp7zy]

@@EngineeringPhysicsbySanjiv ookay sir…but what if someone asks specifically about their corresponding life time…it cant be same exactly for these two states

[@EngineeringPhysicsbySanjiv]

Its not much significant if these are not metastable states