What is a good reference for the quantum mechanical description of lasers? I am currently taking a graduate level class on lasers. The primary focus of the class is on the design and engineering aspects of lasers, e.g. resonator design. However the first portion of the class is an overview of the quantum mechanics of laser processes in semi-classical terms: transition probabilities for a 2-level dipole atom in an external (classical) field, perturbation theory, and matrix QM.
I have an undergraduate degree in physics, so the basics of QM are familiar to me, but it has been years since I seriously applied any of that knowledge. In addition, the professor is moving through this material very rapidly, as it is not the primary focus of the class. I can follow well enough that I'm not worried about my grade, but I'm feeling a bit cheated out of a more thorough understanding of this topic, which I would really like to have. Not only is this subject matter an appropriate level of advancement over my existing knowledge, it is also the basis for something (lasers) which I will likely spend a career dealing with.
Can anybody recommend a text which covers this topic, and would be appropriate for somebody with my background? I would value a clearly written description over absolute rigor, but I am by no means looking for a laypersons description of QM. For example, I am quite comfortable already with the notation and concepts in the textbook "Quantum Mechanics of atoms, molecules, solids, nuclei, and particles" By R. Eisberg and R. Resnick. The ideal reference would be at a similar level of sophistication, but provide a more in-depth look at laser processes in particular.
 A: One of the standard texts for this kind of thing (the quantum mechanics of lasers, without all the technical details you'd need to know to design a real one) is Loudon's Quantum Theory of Light.  I've got the 2nd edition, I think he's up to the 3rd.
In my edition he does the "pre-Quantum" explanation of lasers (i.e. in terms of Einstein A & B coefficients) in about 40 pages.  Over the next 200 pages or so he does the fully quantum treatment of light (quantization of the field, creation and annihilation operators, etc) and then revisits the laser.
The first 40 pages should cover the "clearly written description" criteria, and - as far as it goes - it's relatively rigorous as well.
A: It sounds like what you're asking about is basically atomic physics, rather than laser physics. In which case, I recall Optical Resonance and Two-Level Atoms by Allen and Eberly being useful when I took that back in grad school. There's a good deal of it available on Google Books if you want to check it out. It's short, hits most of the phenomena involving the interaction of light and atoms that you might want to know about, and it's a Dover paperback, so it's cheap for a physics text. It might assume more knowledge than you have, though. Anyway, it's probably worth a look.
Oxford University Press has a series of "Masters" books pitched for advanced undergrads and beginning grad students that might also have something worthwhile. I've used the Quantum Optics volume by Fox, and the Atomic Physics one by foot, and between them they probably cover everything you're after.
