  We study the output from the modes described by the superposition of Gaussian
beams confined in the quasi-stadium microcavities. We experimentally observe
the deviation from Snell's law in the output when the incident angle of the
Gaussian beam at the cavity interface is near the critical angle for total
internal reflection, providing direct experimental evidence on the Fresnel
filtering. The theory of the Fresnel filtering for a planar interface
qualitatively reproduces experimental data, and a discussion is given on small
deviation between the measured data and the theory.
