Saturated absorption: decrease size of material rather than intensity of light?

[franco1991]

In saturated absorption, the decrease in absorption (and corresponding increase in wave transmission) is dependent on the intensity of the incoming wave. But why can't we decrease the size of saturable material, rather than the intensity of light?

According to my understanding, saturable absorption happens because there are more photons than atoms, thus the atoms cannot absorb all the impinging photons, and thus some photons will be transmitted. Is this the case? If it is, then couldn't we just decrease the size of material and thus decrease the number of atoms available to absorb the photons, rather than increasing the number of photons (by increasing the intensity of light)?

The only reason I could see this not working is if saturable absorption is some special phenomena, for example if at high energies the atoms are energized for longer than they normally are, and thus take longer to go back to ground state (which would mean that it does rely on actual intensity rather than the ratio of atoms to photons).

So, which one is it? Is it that the atoms take longer to get back to ground at high energies (in which case decreasing the # of atoms won;t do anything), or is it simply the ratio of atoms to photons, and there being more photons than atoms? (in which case, decreasing the number of atoms should have the same effect as increasing the intensity and thus number of photons in the impinging wave).

 

[eljose79]

Thank you for your question regarding saturable absorption. As a scientist in this field, I can provide some insight into your query.

Firstly, you are correct in your understanding that saturable absorption occurs when there are more photons than atoms. This is due to the fact that the atoms can only absorb a certain number of photons before they reach their maximum energy level and cannot absorb any more. This leads to the excess photons being transmitted through the material.

In response to your question about decreasing the size of the saturable material, this would not necessarily have the same effect as decreasing the intensity of light. This is because the size of the material does not directly affect the number of atoms within it. The number of atoms is determined by the density of the material, not its size. So, decreasing the size of the material would not necessarily decrease the number of available atoms for absorption.

Furthermore, in order for saturable absorption to occur, there needs to be a sufficient number of atoms present in the material. If the size of the material is decreased too much, there may not be enough atoms for the absorption process to take place.

To answer your question about whether saturable absorption relies on the actual intensity of light or the ratio of atoms to photons, it is a combination of both. As mentioned earlier, there needs to be a sufficient number of atoms for absorption to occur. However, the intensity of light also plays a role in determining the amount of absorption that takes place. This is because the higher the intensity of light, the more photons there are to be absorbed by the available atoms.

In summary, decreasing the size of saturable material would not have the same effect as decreasing the intensity of light. Saturable absorption is a result of both the ratio of atoms to photons and the intensity of light. I hope this helps to clarify your understanding of this phenomenon.