Mode discrimination of unstable resonators with spatial filters and by phase modification.
The effects of an intracavity spatial filter in a half-symmetric unstable bare cavity resonator have been studied using iterative propagation techniques to obtain pure l-mode resonator solutions. The results indicate that the mode-loss difference is highest when the spatial-filter radius is at the first or third dark ring of the Airy pattern at the spatial filter. Furthermore, the results are not directly dependent on the resonator-equivalent Fresnel number. Also presented are results indicating that aspherizing the feedback mirror can be done in such a way as to increase mode discrimination.
Southwell
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Rocketdyne Division, Rockwell International Corporation, Canoga Park, California 91304, USA.