Electro-optical light modulators, light wavelength multiplex signal transmitting apparatus and light wavelength separating switches utilizing the same

Claim 1

In a light wavelength multiplex signal transmitting apparatus including a modulator comprising at least one crystal having a refractive index ellipsoid defining a principal axis and manifesting an electro-optical effect which produces rotation of the principal axis of the refractive index ellipsoid under the influence of an applied electric field, the principal axis forming a light path through said crystal, a source of light directed along said principal axis, said source of light having a light spectrum with a half value width of more than 100 A, and light separating means associated with said crystal for converting a single incident polarized light into polarized light components, the improvement wherein there are a plurality of juxtaposed crystals each having a refractive index ellipsoid, and the light separating means comprising electrode means formed on each of said crystals for providing different periods along said principal axis and obtaining multiple modulated polarized light components, said electrode means including a plurality of pairs of comb-shaped electrodes of different periods juxtaposed along said principal axis, and power means connected to said electrode means for applying an independent voltage to each of said pair of electrodes, each of said pairs of electrodes including a first electrode and a second electrode each having a plurality of fingers, the fingers of said first electrode being interdigitally disposed relative to the fingers of said second electrode, the spacing between said fingers being uniform and different from spacing of fingers associated with other said crystals, with the voltages of said power means comprising modulated signal voltages, and birefringence means located on a light output side of said crystals for transmitting particular wavelength components of light to a plurality of light paths.