Electro-optic modulator

In telecommunications, an electro-optic modulator is an optical device in which a signal-controlled element is used to modulate a beam of light. The modulation may be imposed on the phase, frequency, amplitude, or direction of the modulated beam. Modulation bandwidths extending into the gigahertz[?] range are possible with the use of laser-controlled modulators.

Source: Federal Standard 1037C and MIL-STD-188