Semiconductor Mach-Zehnder Optical Modulator and IQ Optical Modulator Using Same

Abstract

A Mach-Zehnder modulator is enabled to perform high-speed modulation operation by reducing RF loss of a high-frequency wiring formed on an optical waveguide without deteriorating optical characteristics of branching and multiplexing optical circuits. The Mach-Zehnder modulator includes a Mach-Zehnder (MZ) optical waveguide including two arm waveguides, a 1×2 multimode interference coupler composed of a semiconductor that splits and distributes input light to the two arm waveguides, a 2×1 multimode interference coupler composed of a semiconductor that multiplexes light from the two arm waveguides, and phase modulation means for giving a phase difference to the light that propagates through the two arm waveguides, wherein the 1×2 multimode interference coupler and the 2×1 multimode interference coupler are formed in a high-mesa structure, and higher mode light radiation means for radiating higher mode light is connected to only the 2×1 multimode interference coupler among the two multimode interference couplers.

Dependencies are inferred from the claim text.