Phys.org October 27, 2020
Researchers in 1958 showed theoretically that the coherence of a beam cannot be greater than the square of the number of photons stored in the laser based on the assumptions they made about how energy is added to the laser and how it is released to form the beam. Now according to researchers in Australia the assumptions made sense at the time, and still apply to most lasers today, but they are not required by quantum mechanics. They have shown that the true limit imposed by quantum mechanics is that the coherence cannot be greater than the fourth power of the number of photons stored in the laser. When the stored number of photons is large, as is typically the case, the new upper bound is much bigger than the old one. Their work raises many interesting questions such as whether it could allow more energy-efficient lasers. They hope to investigate that in the future…read more. TECHNICAL ARTICLE
Credit: Pixabay/CC0 Public Domain