Recent content by Goodver

Hi. I am doing some complex computations using c, c++, matlab, python. It is very slow on a conventional PC. I heard, there is a way to do scientific computations remotely. Such that I could sort of get an access to the remote advanced PC, and perform computation remotely there. And then...

What determines which TEM mode will the laser output have? Why some lasers emit in TEM00, while other in a donut mode, and other in a superposition of multiple modes. Thank you.

Does anyone know if it is possible to get on web an exam sample or quiz or exercises, on "Quantum cascade lasers"? Thank you.

Thank you Cthugha. However this does not answer why intersubband transitions in the VALENCE BAND are not used. As far as I know, only intersubband transitions in the conduction band are used for lasing.

Why for quantum cascade lasers used only intersubband transitions in the conduction band. Although in a heterostructure there are also quantized levels in the valence band, which I think also can be used for lasing? Thank you.

in the dispersion relation curve for phonon, optical branch is not zero at k = 0. Thus generally speaking solid might be transparent for all photon wavelengths except the wavelength which corresponds to the energy of an optical phonon at k = 0. Thus photons can be absorbed or reflected. It says...

I want to follow some certain people who conduct the research I am interested in. I want to be up to date whenever they publish a new article. How can I follow these people? So far for me the convenient way was the researchgate network. But some researches do not have an accounts there, however...

spectral lines As far as I understand spectral lines represent allowed transitions between energy levels in a particular atom. And that the number of energy levels should increase with increase of a number of electrons, due to electron-electron and spin-angular-momentum couplings. Right...

I am confused with the classical approach of usage of a "transition dipole oscillation" in order to explain the broadening of spectrum of emission between energy levels. 1. If I understand it correctly then emission of photon is due to oscillation of a dipole consisting of an electron-proton...

Thank you very much!

By Spontaneous emission it is said that the electron jumps to the higher energy state and then after some time "spontaneously" falls to the lower state. It is still not clear to me, what makes the electron to "fall" back to the lower state, if higher state is also allowed state and excitation...

And the last question (sorry for disturbing). It seems clear why emission of photon does not happen in case of intraband transition between adjacent energy levels in a band. But do I understand it correctly that transition within the band can occur not only between adjacent energy levels, but...

However, I still have a question. Yes I meant intraband transitions, thank you. If we consider intraband transitions as a spontaneous emission, rate of which can be expressed as a Fermi golden rule, then from Fermi golden rule, rate is proportional to the 3d power of angular frequency. As far...

Thank you, this helped!

Thanks for the responses Simon, my question is just are photons emitted in interband transition or not? Or since energy gaps between interband levels are ~0, while electron "drifts" to the edge of the conduction band, we have infinite number of photons with infinite wavelength emitted?