| 摘要 |
PROBLEM TO BE SOLVED: To facilitate stabilizing a signal output by suitably adjusting intensities of output signals entering a multiplexer of an light modulator having a plurality of Mach-Zehnder type waveguides combined into a nesting structure. SOLUTION: The light modulator including a substrate 3 with electrooptical effect, an optical waveguide having a branch formed on the substrate and constituted by arranging the plurality of Mach-Zehnder type waveguides 11 to 14 in parallel and branching waveguides connected to input waveguides of the Mach-Zehnder type waveguides, and the multiplexer where output waveguides from the Mach-Zehnder type waveguides join, and a modulation electrode for modulating an optical wave propagated in the optical waveguide is provided with Y-branch switches 51, 52 at one of positions at the branch, between the branch and an input waveguide of a Mach-Zehnder type waveguide to which the waveguide branching off from the branch is connected, at the multiplexer, and between the output waveguide of the Mach-Zehnder type waveguide and the multiplexer 36, branching ratios of the Y-branch switches being adjustable. COPYRIGHT: (C)2011,JPO&INPIT |
