- #1

Niles

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In almost every book on photonics I've seen, the following expression for the steady state gain is derived

1 + flux/flux

_{saturation}= g

_{small signal}/g,

where I by

*flux*mean intracavity flux and

*g*is the gain. When talking about lasers, then in the very same books (e.g. Saleh/Teich) the authors argue that when lasing begins, the intracavity photon flux increases, hence by the above expression the gain decreases until it settles on its steady state value (which is equal to losses). What I find to be confusing is that the above expression

**only**holds for steady state, but Saleh/Teich (and others) use it to argue that gain decreases

**until**it reaches steady state.

How can they use our steady state expression above to describe the dynamical behavior too?

Niles.