Optically controlled functional elements in the millimeter waveband are described in the paper, based on dielectric image lines (DIL). They include attenuators, amplitude modulators and power switches. Semiconductor Si, GaAs and Ge materials are used, that are light-sensitive at a wavelength (lambda) 0 - 0.9 micrometers DIL elements possess lower losses, smaller size and weight and simpler technology, as compared to known functional elements in this band. Existence of a field outside the DIL allows construction of a narrow-band modulator, in form of a semiconductor resonator coupled with DIL. Illumination of the latter results in a change of its Q-factor. Modulation depth and bandwidth may be thus controlled. Several shapes of resonator are considered, namely circular and elliptic cylinder and a half-sphere. Q- factor may be intensified by application of a high-intensity magnetic field. A number of similar resonators slightly varying in their size are used to increase the modulation bandwidth. Power switch is also described, including two DILs coupled by a semiconductor resonator with Q-factor controlled by light.