Lasers revision by https://padlet.com/mattyj632/ufc1jwxyybbgskvw en-us 2025-04-30 14:48:19 UTC 2026-05-27 10:13:54 UTC hello@padlet.com Past papers mattyj632 https://padlet.com/mattyj632/ufc1jwxyybbgskvw/wish/3431802213 For question 1d on the 2022 ALQ exam paper, why do the populations in N1 and N2 both increase simultaneously for a homogeneously broadened medium? Surely this would not be possible for a fixed number of atoms? 


I think the solution for this question is incorrect: N1 should show a dip on resonance, and N2 should show a peak such that N1+N2=constant.

]]> 2025-04-30 14:49:34 UTC https://padlet.com/mattyj632/ufc1jwxyybbgskvw/wish/3431802213 Workshop 3 Question c) https://padlet.com/mattyj632/ufc1jwxyybbgskvw/wish/3928725571 I dont really understand the concept of image holes from L14. According to the lectures, image holes do not contribute to lasing, but the answer to question c, I believe, includes the image holes in the number of holes that can lase simultaneously. What is the correct answer, and in an exam what should we do?

]]> 2026-05-25 20:27:11 UTC https://padlet.com/mattyj632/ufc1jwxyybbgskvw/wish/3928725571 Typo in equation (23) mattyj632 https://padlet.com/mattyj632/ufc1jwxyybbgskvw/wish/3931340344 There was a typo (extra factor of \pi on the denominator inside the bracket) in equation (23) (Lecture 3: ratio of inhomogeneous and homogeneous lineshapes). The numerical result (0.68 \Delta \omega_I/\Gamma_H) and the graphs, text etc are all correct. The correct equation is shown here. I have updated the complete notes file AND the notes file for lecture 3 on Ultra. Apologies and thanks to Ethan for finding this.

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