Optical Modulator Arm Waveguide Width Segmentation

The arm waveguide is divided into multiple sections with different width characteristics. The first arm waveguide has a third width larger than the first width, while being confined within a first strip region having a fourth width twice as large as the third width. This segmentation allows different portions of the waveguide to serve different functions: the wider sections reduce power density to prevent material deterioration, while the strip region confinement maintains single-mode propagation by preventing higher-order mode excitation.

Different width characteristics are applied to different sections of the arm waveguides. The waveguides have locally optimized widths where the third and fifth widths are larger than the first width to reduce power density, while the strip regions provide local confinement to maintain mode stability. This local quality variation allows simultaneous achievement of material protection and mode control.

The arm waveguide structure is segmented into the waveguide core and the surrounding strip region. The waveguide has a specific width (third or fifth width) optimized for low power density, while the strip region (fourth or sixth width) provides additional lateral confinement. This segmentation enables the waveguide to maintain single-mode propagation through the strip region confinement while the wider core reduces power density to prevent material deterioration.

The solution moves from considering only the waveguide width to including the strip region width as an additional dimensional parameter. By controlling the ratio between the waveguide width and the strip region width (strip region width is twice the waveguide width), the design achieves mode confinement in one dimension while allowing reduced power density through increased waveguide width in the same dimension.