Integrated optics eight-port 90 degrees hybrid on LiNbO/sub 3/

The design, fabrication, and characterization of an integrated optical eight-port 90 degrees hybrid in LiNbO/sub 3/ are discussed. The hybrid is realized as a bridge circuit comprising four directional couplers and two phase shifters, each of the devices being electrooptically tunable. The electrodes are fabricated as combined indium-tin-oxide/gold multilayers. The component provides the desired phase pattern of the intermediate frequency. Measurements on the phase stability of the integrated bridge show phase fluctuations of <+or-5 degrees and a temperature drift of approximately=15 degrees / degrees C. Both may be eliminated by a phase control loop.<
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