  We have shown that a structure composed of a semiconductor hemicylinder and a
dielectric waveguide separated by a thin metal layer permits efficient and easy
light control. In such a system, it is possible to ensure matching between TE
and TM modes of a low refractive index waveguide with the corresponding
whispering gallery modes of the hemicylinder of a higher refractive index, a
circumstance that allows one to reduce the resonator sizes to the order of the
exciting wavelength in the vacuum still having rather high Q-factor around
2*10^4. Due to pronounced electro-optical properties of the resonator medium,
one is able to effectively control the output light intensity by varying the
refractive index of the hemicylinder in the order of 10^(-4).
