Stimulated Emission & Emitted photon direction

In summary, the conversation discusses the process of stimulated emission in lasers, where a photon with the correct wavelength can cause an electron to drop from a higher to a lower energy level, emitting a new photon with the same wavelength, phase, and direction. This process is possible due to CPT symmetry and can be compared to absorption equations, as well as the concept of negative radiation pressure for pulling photons in a given direction.
  • #1
RobbyQ
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TL;DR Summary
Stimulated Emission & Emitted photon direction
I always understood that a photon of correct wavelength would raise the energy level of an electron (which is the case)
But reading about lasers and stimulated emission I read the following where the electron drops a level upon absorption:-
"A photon with the correct wavelength to be absorbed by a transition can also cause an electron to drop from the higher to the lower level, emitting a new photon. The emitted photon exactly matches the original photon in wavelength, phase, and direction. This process is called stimulated emission."

How is this possible i.e dropping to a lower energy level and how/why is the photon wavelength, phase, and direction preserved?
 
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  • #2
Stimulated emission-absorption equations would be exchanged if performing CPT symmetry, suggesting they are CPT analogs - also through B_{12}=B_{21} symmetry for their Einstein's coefficients.

If so, and absorption is from positive radiation pressure, pushing photons into a target (from given direction) ... maybe we should think about stimulated emission through negative radiation pressure, pulling of photons (in given direction)?
https://scholar.google.pl/scholar?q=negative+radiation+pressure
https://www.physicsforums.com/threads/negative-radiation-pressure.1053657/
 
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1. What is stimulated emission?

Stimulated emission is a process in which an excited atom or molecule releases a photon of light when it interacts with another photon of the same energy. This process is the basis of laser technology.

2. How does stimulated emission differ from spontaneous emission?

Spontaneous emission occurs when an excited atom or molecule releases a photon of light without any external stimulus. In stimulated emission, the release of the photon is triggered by the presence of another photon.

3. What is the direction of the emitted photon in stimulated emission?

The direction of the emitted photon in stimulated emission is the same as the direction of the stimulating photon. This is known as the principle of phase matching.

4. What is the significance of stimulated emission in laser technology?

Stimulated emission is the mechanism by which lasers produce a highly focused and coherent beam of light. By controlling the direction and timing of the stimulating photons, a laser can produce a concentrated beam of light with a specific wavelength and phase.

5. Can stimulated emission occur in materials other than atoms and molecules?

Yes, stimulated emission can also occur in other types of materials, such as semiconductors and quantum dots. In these materials, electrons can be excited to higher energy levels and release photons when they interact with other photons of the same energy.

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