Significant deformations and propagation variations of Laguerre-Gaussian beams reflected and transmitted at a dielectric interface

We observe TM and TE Laguerre-Gaussian (LG) light beams reflected and transmitted at a dielectric interface near critical incidence. The intensity distribution of the reflected beam is transversely deformed near the beam waist, and that of the transmitted beam is similar to that of a diagonal Hermite-Gaussian beam. The former rotates around the optical axis by approximately π/2 with propagation, and the latter returns to that of the incident LG beam. These observations agree well with numerical calculations based on an angular spectral analysis and are attributable to the helical wavefront of the LG beams, the sharp incidence-angle dependence of the Fresnel reflection and transmission coefficients, and the Gouy phase.