Novel structure for electro-optic intensity modulators: the radiation mode modulator

In this communication we report a novel structure for the electrooptic intensity modulation. To transfer the phase modulation into intensity modulation, the structure proposed uses the the interference between a guided mode and a group of radiation modes, generated at an optical discontinuity. The structure is studied using the standard BPM as well as a modal technique based on the analysis of the radiation mode spectrum of the optical field. An extinction ratio in the order of 7 dB is obtained and a higher ratio is expected for an optimized structure. This structure seems to be promising for waveguide modulators as it shows several practical advantages compared to the classical Mach-Zehnder or directional coupler modulators.