Geometric formulation of unstable-resonator design and application to self-collimating unstable-resonator diode lasers

A new set of design parameters for unstable resonators is presented that yields simpler expressions for the mirror and beam radii and magnification than those given by the usual g parameters. The new formalism is applied to determine the design of a solid unstable resonator of index n with a self-collimated output beam, applicable to unstable-resonator diode lasers.