STOP and GO a probe laser beam on a silicon-based dielectric surface.

We show experimental evidence for retaining the energy of a probe laser beam on a silica-based crown glass surface through destructive interference with a stronger coupling laser which irradiates the same surface dipoles. Both lasers are linearly polarized. The probe is incident within 10 deg. near Brewster angle (BA) and the parallel component of its reflectance is analyzed. The coupler's beam is at normal incidence on the surface, so that the paths of least-time for the two beams is different. The probe-coupler interaction is assisted by a capacitor configuration using silica-glass as dielectric. When the probe has a lower photon energy than the coupler, the interaction with a stronger coupler at capacitor voltages below 0.4eV indicates three regions located at larger angles than BA: (1) a Brewster region (BR) of 2 deg. wide around BA, where the interaction between the probe and the surface dipoles is inhibited by the coupler; (2) a region of coherent interference, although of weak intensity, which is 3.5 deg. wide outside BR, where the parallel reflectance shows a regularly distributed max-min fringe pairs following the typical cosine function of an interfernce term; and (3) a region dominated by the probe’s reflectance which follows a perfect parabolic shape. We can identify pairs of voltages where for one angular position the probe is stopped to be reflected at low voltage and is highly reflected at larger voltage. Such change in the optical reflectivity can be used as an optoelectronic switch with STOP and GO modes.