Method and device for controlling a beam of light

Abstract

Method and device for controlling a beam off light (17), which is coupled in into a working layer (2) of electro-optical material and which is supplied to a working area (16). In a first optically conductive state the working area has a poling mode which differs from the one of the surrounding working-layer material (7), as a consquence of which other refractive indices will arise, due to which the working area will form a light waveguide through which the beam of light coupled in will be conducted (19) to a first glass fibre (22). In a second optically conductive state the working area has a poling mode which is equal to the one of its surroundings. Because of the fact that the refractive indices inside and outside the working area are not equal, the working area will not form a light waveguide, but (e.g.) a light insulator or a light reflector, by means of which the beam of light coupled in will be conducted to a second glass fibre (21). The quasi-stationary poling mode of the working area required for the first respectively the second optically conductive state will be reached by successively--warming up the working area to above the softening temperature--exciting an electric field in the working area, and--letting the working area cool down again. For poling the electric field has a value unequal to 0; for unpoling a value equal to 0.