Відео

The intro reminds me of the pbs specials I grew up with, also this video is fantastic. I believe I will watch more in the future, however shg is really the only reason I came here for now 😅

The og professor

thannnk you wow

Sir next session this course will come??

Confusion created

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

In case of three level system why can't we achieve population inversin between state 2 and 3 instead of 3 and 1

14:46 "z", not "x"

20:02 Maiman did indeed create the first laser (ruby) in 1960, but he did NOT add the Fabry-Perot resonator. Townes, Badov, and Prokhorov did to their device, which is why they got the Nobel.

Super useful! Thank you for your video

is it necessary to have a standing wave in the cavity in order to get laser emission? also does stimulated emission not work unless the mirrors are set at certain distance intervals and if so pls explain

Confusing and boring lecture 😐

Thank you so much!!!!!😃

Birefringent crystals?!?!?!?! Is that legal????

Oh this teaching is superb! Amazing content.

tooo boaring class

How can you create mirrors that will withstand the photon barrage within the cavity, when the whole idea is to produce a stream of photons strong enough to go through metal???

30:38 A femtosecond is 10^-15 sec.

These chapters are repeats. WTF???

Starting my PhD this Fall. Taking Lasers. This playlist is appreciated. Question: What textbook would you recommend for graduate students studying Lasers?

laser are monochromatic but how different modes (wavelengths/ frequencies) can exist in the cavity?

Copy paste 😂😂, teaching style is worst , boring, like story telling

You should not be a teacher sir

Best explanation of NLO

Given very good explanation which helps the students around the globe. It is really helpful for final exam preparation

Thank you sir. Very well explained🙏

Excelent explanation!

Why is it so obvious that all photons are emitted in same direction and have same phase?can anyone suggest any mathematical reference where I can understand it?

you have become the best optics teacher ever for me. Thanks a lot for your content

Thank you

Very conceptual lecture thanks this type of explanation and devotion in your teaching field

00:03 Power in continuous and pulsed lasers 03:39 Pulse lasers have both average power and peak power. 06:56 Pulse width defines the duration of light emission. 10:03 Relationship between average power and peak power in pulse lasers. 13:20 Duty cycle is the fraction of time the laser pulses are on. 16:36 Peak power and average power have different values based on the energy production over time. 19:17 Pulse lasers have peak power much higher than average power 21:53 Understanding pulse shape and its relation to pulse width. 24:18 Pulse shape dictates pulse width 26:57 Power is a product of pulse width and spectral bandwidth 29:29 Transform limit is important for ultra short pulses 31:51 Ways to make a laser pulsed Crafted by Merlin AI.

Amazing explanation sir❤

I'm glad I can speed this up.

Every concept seems to be "important". If so, don't mention it all the time.

If "phase" is so important in this lecture, why didn't he explain this concept? Heisenberg Uncertainty Principle: dE . dt = d(h.f) . dt = h . df . dt > h-bar/2 In this video he uses the Full Width at Half Maximum (FWHM) for line width.

I ve a confusion related to the constant value of A/B= 8πhv^3/c^3 ( Eugene Hecht) book of optics. But you have written it as A/B=2hv^3/c^2 Plz explain it sir ..

The units of the Einstein B-coefficient are: m^3 / (J.sec.)

In Quantum Physics it is assumed that spontaneous emission is triggered by vacuum energy fluctuations.

@ 01:33 In my opinion, L = m . (1/2 . wavelength) is the more intuitive version for this equation. All allowed modes of EM-radiation in a cavity L are multiples of half their wavelength. @ 26:01 He meant to say: "where amplification A exceeds the losses L." Thus, gain G = A - L.

The Nd:YAG laser was introduced in 1964. Nd:YAG = Neodymium-doped Yttrium Aluminum Garnet; this is a crystal.

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

Don't ever think that a LASER can generate any net surplus of energy! It can't. Its energy-input is bigger than its output. It consumes energy. @ 17:07 You get this expression in equilibrium, when dN2/dt = 0

@ 19:35 The first MASER was built in 1953, the first LASER in 1960.

@ 6:38 Not really, because we already invested a photon to get the atom excited. So overall, we still have: 2 IN = 2 OUT. We need differences in energy-level life-times.

The title is not accurate. You cover the fundamentals here, not modes.

Poor explanation of phase-matching; very chaotic.

@ 0:40 Once again, the E-field must be multiplied by the vacuum permittivity too. Source: en.wikipedia.org/wiki/Electric_susceptibility#Nonlinear_susceptibility

@ 25:00 Here the E-field must be multiplied by the vacuum permittivity too!

Laser is not really tunable, is it?