Edge Couplers with Trident Waveguide Inverse Tapers

The edge coupler is divided into multiple waveguide cores (first, second, and third waveguide cores) with different inverse taper configurations. Each waveguide core handles a portion of the light mode transformation, distributing the coupling function across multiple segments rather than relying on a single structure, thereby reducing overall insertion loss.

Multiple waveguide cores with inverse tapers are combined to form a composite edge coupler structure. The first, second, and third waveguide cores work together to transform the laser mode into the waveguide mode, merging their confining capabilities to achieve better mode matching and reduce coupling loss.

Instead of using a single wide waveguide core to achieve field confinement, the structure segments the confinement function across multiple waveguide cores with different inverse taper widths. This allows effective mode transformation and field confinement within a more compact overall footprint.

Different waveguide cores have different inverse taper characteristics optimized for their specific roles in mode transformation. The first, second, and third waveguide cores exhibit varying taper slopes and widths tailored to their individual positions in the mode conversion sequence, achieving efficient confinement without uniform expansion of device size.

The mode transformation process is segmented into multiple stages across different waveguide cores, with each core contributing to progressive mode matching. This distributed approach allows smoother mode transition and reduces abrupt reflections that occur in single-stage couplers.

The inverse taper structures are designed to manage and redirect reflected modes rather than simply eliminating them. By carefully configuring the taper geometries of multiple waveguide cores, harmful back reflections are converted into manageable components that can be directed away from sensitive regions, transforming a harmful effect into a controllable feature.