Stimulated Emission: Intuitive Explanation Needed

In summary, stimulated emission is a quantum mechanical phenomenon where a photon with the right frequency can interact with an excited electron and create a copy of itself, putting the electron into a lower energy state. This is similar to the excitation of an unexcited electron, but the reasoning behind it is less intuitive. In many optical phenomena, the atom is considered as a harmonic oscillator and the absorption and emission processes are dependent on the strength of the incoming wave. Stimulated emission occurs when the phase difference between the incoming wave and the atomic oscillator reaches a certain point, resulting in reinforcement of the incoming wave. This is different from spontaneous emission, which occurs in all directions and is not dependent on the incident wave.
  • #1
sokrates
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I am trying to find an intuitive explanation for the stimulated emission phenomenon. I know the effect: a photon with the right frequency "interacts" with an excited electron to create a copy of itself( same phase, same amplitude, same state) putting the electron to a lower energy state...

But this doesn't fit as easily as the excitation of an unexcited electron...What I mean is, a photon with the right energy interacts with an electron and puts the electron into an excited state. This is much more intuitive and reasonable, at least for me.

I am trying to find a similar reasoning for the stimulated emission, is there one that you guys know of?
 
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  • #2
In many optical phenomena, the quantum mechanical picture is consistent with what we would expect from classical electromagnetic theory, with the atom considered as a harmonic oscillator. The atom is resonant with a particular frequency, but the relative phase of the atomic oscillator is almost completely random with respect to the incoming light. As the phase difference varies through 360 degrees, there is a point where the absorption from the incoming wave is a maximum. You can analyze this by taking the superposition of the incoming wave with the ordinary classical donut-shaped radiation pattern of an oscillating dipole. When this calculation is done, there is a shadow zone behind the oscillator where the incoming wave is diminished.

Let the phase shift another 180 degrees and the situation is reversed. The superposition of the two wave patterns now re-inforces the incoming wave. That's stimulated emission.

Both the absorption and emission processes described above depend on the strength of the incoming wave. For a given oscillator amplitude, the rate of absorption or emission is linear with the ambient field strength. There is also another kind of emission going on all the time which doesn't depend on the incident wave. It's just the same classical radiative donut pattern as calculated in all other directions (outside the above-mentioned "shadow zone") where there is effectively no significant interaction between the two wave patterns. That's spontaneous emission.
 
  • #3


Stimulated emission is a phenomenon that occurs when an excited electron interacts with a photon of the same frequency and phase, resulting in the emission of a second photon with identical characteristics. This process is an essential component of laser technology and plays a crucial role in various other fields of science.

To understand stimulated emission intuitively, it is helpful to think of the excited electron as a ball sitting at the edge of a cliff. When a photon with the right energy comes along, it can push the ball over the edge, causing it to fall to a lower energy state. This is similar to the process of excitation, where the photon "pushes" the electron to a higher energy state.

Now, imagine that there are multiple balls at the edge of the cliff, all in the same excited state. When a photon of the same frequency and phase interacts with one of these balls, it can cause it to fall to a lower energy state, releasing a photon in the process. This newly released photon can then go on to interact with another excited ball, causing it to release another photon, and so on. This chain reaction results in a cascade of photons being emitted, which is what we observe as stimulated emission.

In this analogy, the photon acts as a trigger for the excited electron to release its energy and return to a lower energy state. This is why stimulated emission is often referred to as "induced emission" - the electron is induced to emit a photon by the presence of a triggering photon.

Overall, stimulated emission can be thought of as a natural process of energy release, similar to how a ball will naturally roll down a hill when given a push. This intuitive explanation can help us understand the mechanism behind stimulated emission and its role in various scientific applications.
 

What is stimulated emission?

Stimulated emission is a process in which an excited atom releases a photon of light when it interacts with a passing photon of the same frequency. This results in the amplification of light, similar to the process used in lasers.

How does stimulated emission work?

Stimulated emission involves an excited atom that has excess energy. When a photon of the same frequency as the atom's excess energy passes by, the atom is stimulated to release its excess energy in the form of a photon. The released photon has the same frequency, direction, and phase as the passing photon, resulting in the amplification of light.

What is the difference between stimulated emission and spontaneous emission?

Spontaneous emission occurs when an excited atom releases a photon of light without any external stimulation. This process is random and results in the emission of photons in all directions. On the other hand, stimulated emission requires an external photon to interact with the excited atom, resulting in the emission of a photon with the same properties as the external photon.

What is the significance of stimulated emission?

Stimulated emission is the basis for the operation of lasers, which are used in various scientific, medical, and industrial applications. It allows for the amplification of light and the production of coherent, monochromatic light beams that are highly useful in many fields of research and technology.

What are some real-world applications of stimulated emission?

In addition to their use in lasers, stimulated emission and the resulting amplification of light are also used in optical amplifiers and telecommunications technology. They have also found applications in medical treatments, such as laser surgery and therapy, and in various scientific experiments and measurements.

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