Unstable resonator with canceling edge waves: rectangular aperture.
The deleterious effects of diffraction by the outcoupling aperture on optical resonator intensity profiles, feedback ratios, alignment sensitivities, and dependence of mode separation on Fresnel numbers can be alleviated by adding a phase step near the edge of the feedback mirror. The required locations and magnitudes of the steps for rectangular apertures are shown to be near the values for circular apertures. Improvements in intensity profiles are shown for both centered and off-centered apertures. Failure of the method when one edge of the aperture approaches the optic axis is analyzed.
Ferguson
T R
TR
U.S. Air Force Weapons Laboratory/ARDF, Kirtland Air Force Base, New Mexico 87117-6008, USA.
Smithers
M E
ME
Perkins
J F
JF