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

• US 4,327,971 A
• Filed: 06/01/1979
• Issued: 05/04/1982
• Est. Priority Date: 06/05/1978
• Status: Expired due to Term

• Current Assignee: Nippon Electric Company Limited (NEC Corporation)
• Original Assignee: Nippon Electric Company Limited (NEC Corporation)
• Inventors: Ohta, Yoshinori, Kondo, Michikazu, Sakaguchi, Mitsuhito
• Primary Examiner(s): Punter, William H.
• Application Number:
  US06/044,373
• Time in Patent Office: 1,068 Days
• Field of Search: 350/149-150, 350/356, 350/96.13, 350/96.14, 350/96.15, 350/336, 350/352, 350/388, 350/392, 333/195-196, 333/203, 333/188, 333/204
• US Class Current: 359/250
• CPC Class Codes: G02F 1/035 in an optical waveguide structure
• CPC Class Codes: G02F 2201/124 interdigital
• CPC Class Codes: G02F 2203/055 wavelength filtering

Abstract

In a light wavelength separating modulator there is provided a crystal manifesting an electro-optical effect which rotates the principal axes of the refractive index ellipsoid of the crystal, a plurality of juxtaposed electrodes formed on the crystal in the direction of transmission of light and having different periods, and means for applying modulation signals to respective electrodes. When light generated by a light source, having a light spectrum where half value bandwidth exceeds 100A, is transmitted through the modulator, a light wavelength multiplex signal transmitting apparatus is obtained; whereas when a birefringence body is located on the output side of the modulator, a light wavelength separating switch is obtained.

Claims

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.