Stepped Optical Bridge for Semiconductor Waveguide Coupling
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Solution Overview
Problem
There is a need for improved methods and systems related to photonic integrated circuits (ICs) utilizing silicon substrates, as silicon is not a direct-bandgap material, and existing technologies lack efficient optical coupling between semiconductor waveguides and active regions.
Innovation Solution
A photonic device is fabricated using a semiconductor wafer with a waveguide and a semiconductor chip bonded to it, featuring a recess and optical bridge for efficient optical coupling, where the optical bridge interfaces with the active region and the waveguide, forming a step at the end of the waveguide to enhance coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon substrate is used for photonic ICs, then manufacturing compatibility and integration are improved, but optical coupling efficiency deteriorates due to silicon being non-direct-bandgap material
Solution Approach 1:
The patent introduces an optical bridge structure as an intermediary element between the silicon waveguide and the semiconductor active region. This optical bridge, formed with high-refractive-index material, mediates the optical coupling process, enabling efficient light transfer from the III-V active region to the silicon waveguide despite silicon's non-direct-bandgap nature. The bridge structure includes a first portion extending from the active region and a second portion extending to the waveguide, creating a continuous optical path that overcomes the material incompatibility.
2Device complexity
If conventional planar structure is used, then fabrication simplicity is improved, but optical confinement and coupling efficiency deteriorate
Solution Approach 1:
The patent transitions from a conventional planar structure to a three-dimensional stepped structure. The optical bridge is formed with vertical height and lateral extension, creating multiple levels and surfaces. This dimensional change enables effective optical confinement by providing vertical interfaces for total internal reflection and lateral extension for mode matching, significantly improving coupling efficiency while remaining compatible with standard semiconductor fabrication processes.
Solution Approach 2:
The patent modifies the optical path parameters by introducing the optical bridge structure with specific geometric parameters including height, width, and length. The bridge structure creates multiple interfaces with different refractive indices, changing the optical path and enabling effective mode coupling. The stepped configuration provides different optical path lengths and interface angles, optimizing the coupling efficiency between the active region and waveguide.
3Device complexity
If direct coupling between waveguide and active region is attempted, then device complexity is reduced, but coupling efficiency deteriorates due to mode mismatch
Solution Approach 1:
The patent segments the optical coupling path into distinct portions: a first portion of the optical bridge extending from the active region, and a second portion extending to the waveguide. This segmentation allows each portion to be optimized for its specific function - the first portion for mode matching with the active region and the second portion for coupling to the waveguide. The segmented structure effectively bridges the mode mismatch between the two components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables effective optical coupling between the waveguide and the active region, improving the performance of photonic ICs by providing vertical and lateral optical confinement, thereby enhancing the efficiency of optical transmission.
Implementation Method 1
providing vertical and lateral optical confinement
Data Source
AI summary
A photonic device includes a semiconductor wafer having a waveguide formed therein. An end of the waveguide includes a step. The photonic device further includes a semiconductor chip bonded to the semiconductor wafer and having an active region, and a waveguide coupler disposed in a gap between a sidewall of the semiconductor chip and the end of the waveguide. The waveguide coupler includes an optical bridge that has a first end and a second end opposing the first end. The first end of the optical bridge is interfaced with a facet of the active region of the semiconductor chip. The second end of the optical bridge is interfaced with the end of waveguide, and has a portion thereof disposed over the step at the end of the waveguide.