Through-Substrate Grating Coupler for Tolerant Chip-Fiber Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical connectors for Co-Packaged Optics (CPO) face high process complexity, low precision tolerance, and inadequate coupling efficiency due to increased fiber connectivity demands, with existing solutions like glass bridges and lens arrays being costly and complex to manufacture.
Innovation Solution
An optical chip-fiber coupler using a through-substrate collimating grating with a chirped grating array, total internal reflection microprism, and microlens array to collimate light beams into parallel light for efficient coupling, allowing for a large alignment tolerance and pluggable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional optical connectors (MPO) are used for fiber array coupling, then fiber connectivity is achieved, but coupling complexity and process difficulty increase significantly
Solution Approach 1:
The invention extracts the coupling function from complex mechanical connectors and integrates it directly into the optical chip substrate through etched grating structures. This eliminates the need for separate alignment mechanisms and mechanical coupling components, reducing overall system complexity while maintaining fiber connectivity.
Solution Approach 2:
The grating structure acts as an intermediary optical element that transforms the coupling interface. By using diffraction gratings etched into the substrate, the invention creates an intermediate optical field that enables automatic mode matching between fiber arrays and optical chips, simplifying the coupling process.
2Reliability
If glass bridge interfaces are used for optical coupling, then coupling efficiency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of using expensive glass bridge structures, the invention creates optical coupling paths directly etched into the substrate using standard semiconductor fabrication processes. The grating patterns are copied from design data through photolithography and etching, eliminating the need for complex glass bonding and alignment processes.
Solution Approach 2:
The invention changes the structural parameters of the substrate by creating periodic grating patterns with specific pitch and depth values. These parameter changes enable the substrate to function as an optical coupling interface without requiring additional glass bridge components, reducing manufacturing complexity while maintaining coupling efficiency.
3Manufacturing precision
If lens arrays are used for light coupling, then alignment tolerance is reduced, but process precision requirements increase
Solution Approach 1:
The grating structures are self-aligned to the optical waveguides through the fabrication process sequence. The gratings are defined relative to the waveguide positions using the same lithography alignment references, automatically ensuring proper spatial relationship without requiring separate alignment steps or high-precision manual positioning.
Solution Approach 2:
The invention merges the grating coupling function with the substrate structure itself. The grating patterns are integrated directly into the substrate layers alongside the waveguides, combining multiple functions into a single monolithic structure that reduces the number of separate components and alignment requirements.
4Ease of manufacture
If optical devices are arranged in fixed positions, then electrical interface constraints are satisfied, but optical coupling efficiency decreases
Solution Approach 1:
The invention enables optical coupling from the bottom surface of the substrate, adding a third dimension to the optical interface. This allows optical waveguides to be positioned optimally for electrical connections on the top surface while maintaining efficient optical coupling through the bottom-grating interface, decoupling the two design constraints.
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
Improves coupling efficiency and alignment tolerance, enabling a two-dimensional array arrangement of optical devices without constraints from electrical interfaces, simplifying the packaging process and enhancing integration density.
Implementation Method 1
the light output from the optical waveguide array is diffracted toward the substrate through the collimating grating array
Implementation Method 2
a total internal reflection microprism and a microlens array to collimate light beams into parallel light for coupling
Implementation Method 3
a total internal reflection microprism and a microlens array to collimate light beams into parallel light for coupling
Data Source
AI summary
An optical chip-fiber coupler based on a through-substrate collimating grating, comprising:; a flip-chip mounted optical chip comprising at least one optical device, an optical waveguide array, and a collimating grating array, wherein the collimating grating array is provided with gradient periods and duty cycles, so that light output from the optical waveguide array is diffracted toward the substrate through the collimating grating array, and the light propagates to a back surface of the optical chip in a substantially collimated manner. An optical coupling element array is arranged on the back surface of the optical chip at positions corresponding to light emission from the collimating grating array to couple the light to an optical fiber array. This structure achieves high-efficiency coupling between optical chips and optical fiber arrays and can be widely applied in fields such as optical IO and CPO for large-scale optoelectronic integrated chips.