He-Ne LASER Action Clarifications

[precise]

1. Won't the electrons get knocked out of the atom during the pumping action instead of just getting excited to higher energy level in LASERS?

2. why doesn't the electron in meta stable state(higher energy state) go to much higher energy level during STIMULATED emission instead of losing energy and emitting a photon? This is the opposite of ionization of the atom, if I'm not wrong.

3.Finally, what happens to the light emitted by spontaneous emission in HE-Ne laser? Won't it mix with the LASER light?

 

[mfb]

1. Won't the electrons get knocked out of the atom during the pumping action instead of just getting excited to higher energy level in LASERS?

I guess that can happen, but it does not contribute to the laser action.

2. why doesn't the electron in meta stable state(higher energy state) go to much higher energy level during STIMULATED emission instead of losing energy and emitting a photon?

Stimulated emission means it emits an additional photon, so it has to lose energy.
There is no higher energy level with the right energy difference to reach with those photons.

This is the opposite of ionization of the atom, if I'm not wrong.

No, as there are no free electrons involved.

3.Finally, what happens to the light emitted by spontaneous emission in HE-Ne laser? Won't it mix with the LASER light?

It is part of the emitted light, yes.

 

[precise]

Thanks mfb for the response. I have got one more question.

When we say the LASER is coherent, what does it mean? What does it mean to be non-coherent? What does a monochromatic, non-divergent and COHERENT light has that a monochromatic, non-divergent and NON-COHERENT lacks? Does it have less number of photons per unit area per unit time or is it energy of each photon is it something else?

 

[mfb]

See coherence at wikipedia. The photons are in phase.

 

[paranormal]

1. It is true that electrons can be knocked out of the atom during the pumping action in a LASER. However, this is not the case in all types of LASERs. In a He-Ne LASER, the pumping action is done through an electrical discharge, which does not have enough energy to completely ionize the atoms. Instead, it excites the electrons to higher energy levels, resulting in a population inversion and the emission of coherent light.

2. The electron in the metastable state does not go to a higher energy level during stimulated emission because it is already in the highest energy state that it can occupy in the He-Ne atom. The emission of a photon during stimulated emission is a result of the electron transitioning back to its ground state, releasing the excess energy as a photon. This is not the opposite of ionization, as ionization involves the removal of an electron from an atom, while stimulated emission involves the release of energy from an already excited electron.

3. The light emitted by spontaneous emission in a He-Ne LASER is not typically used for the laser's intended purpose. This is because the emitted light is not coherent, meaning that the photons are not in phase with each other. As a result, it does not contribute significantly to the laser beam and is often filtered out. However, in some cases, this light can be used for other purposes, such as for spectroscopic analysis. It is important to note that the spontaneous emission does not mix with the laser light, as the laser light is highly directional and travels in a specific path, while the spontaneous emission is emitted in random directions.