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/
 
Last edited:

Related to Stimulated Emission & Emitted photon direction

What is stimulated emission?

Stimulated emission is a process where an incoming photon causes an excited electron to drop to a lower energy level, releasing a second photon with the same energy, phase, and direction as the incoming photon. This principle is fundamental to the operation of lasers.

How does the direction of the emitted photon compare to the stimulating photon?

The emitted photon in stimulated emission has the same direction as the stimulating photon. This directional coherence is one of the key features that make lasers produce highly collimated beams of light.

Why is the phase of the emitted photon important in stimulated emission?

The phase of the emitted photon is important because it is identical to the phase of the stimulating photon. This phase coherence is crucial for the constructive interference of light waves, which enhances the intensity and coherence of the laser beam.

What role does stimulated emission play in laser operation?

Stimulated emission is the fundamental mechanism that allows lasers to amplify light. In a laser, a population inversion is created, and when photons pass through this medium, they stimulate the emission of additional photons, leading to a cascade effect that produces a coherent and intense beam of light.

Can stimulated emission occur in any direction?

While spontaneous emission can occur in any direction, stimulated emission produces photons that travel in the same direction as the stimulating photons. This directional property is harnessed in laser cavities to produce a highly directional beam of light.

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