| 摘要 |
PROBLEM TO BE SOLVED: To provide a nested modulator wherein circuit disposition of modulation electrodes including signal electrodes is simplified and reduction of driving voltage can be attained. SOLUTION: In the nested modulator which includes a substrate 20 comprising a material having an electrooptical effect, an optical waveguide formed on the substrate and the modulation electrodes modulating an optical wave guided in the optical waveguide, and wherein the optical waveguide has a main Mach-Zehnder type waveguide 1 and sub Mach-Zehnder type waveguides 2 and 3 provided to two branched waveguides of the main Mach-Zehnder type waveguide and the modulation electrodes are provided to sub branched waveguides of the sub Mach-Zehnder type waveguides, polarization inversion regions 46 and 47 are formed at a part of the sub branched waveguide of each sub Mach-Zehnder type waveguide and the modulation electrodes are formed of the signal electrodes and grounded electrodes and disposed so as to make the signal electrodes 41 and 44 branched from respective single introduction signal electrodes 40 and 43 act on the two sub branched waveguides of the respective sub Mach-Zehnder type waveguides. COPYRIGHT: (C)2008,JPO&INPIT
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