Phase Conjugation | Not so Scary

There has been a lot of talk about "phase conjugation" lately. It's nothing new and not that scary :)

Correct, there is no difference in the total energy output when two laser beams cross, regardless of whether you consider it from a macroscopic or microscopic perspective. The principles of conservation of energy apply in both contexts, ensuring that the total energy remains constant and no new energy is created merely by the interaction of the beams.

ChatGPT
Macroscopic Perspective:
Energy Consideration: At the macroscopic level, if two 100-watt lasers cross, the total output power combined is still 200 watts. There is no increase in total energy output; the energy is just redistributed within the space where the beams intersect. The observable effects might include a higher intensity at the point of intersection, but this simply results from the superposition of the two beams' energies and does not signify new energy creation.
Microscopic Perspective:
Photon Interactions: At the microscopic level, examining how individual photons interact might reveal complex behaviors such as interference patterns, photon-photon scattering, or other quantum mechanical effects. However, these interactions do not result in an increase in the total energy. They may alter the direction, phase, or distribution of the energy, but the sum total of the energy remains unchanged.
Conclusion:
The output in terms of energy from the crossing of two lasers is strictly governed by how much power each laser outputs. Any seeming increase at the point of intersection is due to the concentration of both beams' energy in a small area, not because there is an actual increase in energy being generated. This holds true whether looking at the interaction with the naked eye (macroscopically) or examining the behavior of individual photons and their interactions with matter (microscopically).

This adherence to the conservation of energy is a fundamental concept in physics that applies across all sc..