| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a nested modulator having a simplified circuit layout of modulation electrodes including signal electrodes and capable of operating at a reduced drive voltage. <P>SOLUTION: A nested modulator includes a substrate 20 made of an electro-optical material, an optical waveguide formed on the substrate, and modulation electrodes for modulating a light wave propagating through the waveguide. The waveguide includes a main Mach-Zehnder waveguide 1 and sub Mach-Zehnder waveguides 2, 3 provided on two branch waveguides, and the modulation electrodes are provided on sub-branch waveguides of the sub Mach-Zehnder waveguides. A polarization reversal regions 46, 47 are formed on a portion of a sub-branch waveguide on the same side of each sub Mach-Zehnder waveguide and modulation electrodes, comprising a signal electrode and a ground electrode, are formed such that, for each sub Mach-Zehnder waveguide, signal electrodes 41, 44 branching off from a single signal injection electrode 40, 43 are laid out to act on both of the sub-branch waveguides and are merged together to be led out thereafter. <P>COPYRIGHT: (C)2013,JPO&INPIT |
