Re: Q: unstable resonators


Andy Resnick wrote:
I'm currently enrolled in a "systems control engineering" class, and
it's been really great- lots of information about closed-loop system
design, transfer functions, stability, etc. etc.

I vaguely recall from my optics classes a couple of things:

1) there is a class of unstable laser resonator designs that are
occasionally used. I can't recall *why* someone would do this, any hints?

My recollection of the engineering motivation is that the ray-unstable
modes inside the cavity have a larger *volume* in space than the
familiar ray-stable modes. Thus an 'unstable mode' will effetively
address more atoms in the gain medium, and will therefore be able to
extract a larger amount of energy from a pumped sample of atoms. For a
pulsed laser, this is clearly a desireable mode of operation.

Cheers, David (cw-only) Van Baak

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