Stacked Photonic Chip Coupler for SOI Fiber Mismatch
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Solution Overview
Problem
Conventional edge coupling methods for fiber-to-photonic chip coupling result in significant optical loss due to mode mismatch between optical fibers and silicon-on-insulator (SOI) waveguides, limiting transmission efficiency and compatibility with mature package technologies.
Innovation Solution
A bonded-two-chip coupler design, where a silica waveguide chip with a micron-scale structure is flipped and bonded onto a silicon photonic chip with a nano-scale waveguide, utilizing a surface grating coupler to achieve mode matching and reduce coupling loss, while allowing for flexible integration of additional functionalities like wavelength division devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional edge coupling is used for fiber-to-photonic chip coupling, then compatibility with mature package technology is achieved, but optical loss increases significantly due to mode mismatch
Solution Approach 1:
The patent introduces an intermediary coupling structure consisting of a silica waveguide layer with a larger mode field diameter that acts as a mediator between the optical fiber and the silicon photonic chip. This intermediate layer transforms the mode field distribution, enabling efficient coupling while maintaining compatibility with mature packaging technologies.
Solution Approach 2:
The patent changes the physical parameters of the coupling interface by using a silica waveguide with a larger cross-sectional area and different refractive index compared to the silicon photonic chip. This parameter transformation allows the mode field diameter to expand from the nanoscale silicon waveguide to a scale compatible with standard optical fibers, reducing coupling loss.
2Loss of energy
If a larger mode field diameter is used to reduce coupling loss, then coupling efficiency improves, but device complexity increases due to additional chip structures
Solution Approach 1:
The patent segments the photonic system into two separate chips: a silicon photonic chip for active photonic functions and a silica waveguide chip for coupling functions. This segmentation allows each chip to be optimized independently, with the silica chip providing the larger mode field diameter needed for efficient fiber coupling without complicating the silicon photonic chip design.
Solution Approach 2:
The silica waveguide chip serves as an intermediary component that handles the mode field transformation, thereby simplifying the overall system architecture by separating the coupling function from the active photonic processing function.
3Productivity
If nano-scale waveguides are used in photonic chips, then integration density increases, but mode mismatch with optical fibers worsens leading to higher optical loss
Solution Approach 1:
The patent divides the system into a compact silicon photonic chip with nano-scale waveguides for high integration density and a separate silica waveguide chip with larger dimensions for efficient fiber coupling. This segmentation allows the nano-scale integration benefits to be preserved while eliminating the mode mismatch problem at the fiber interface.
Solution Approach 2:
The patent transitions from a single-chip three-dimensional integration approach to a multi-chip stacked architecture, effectively adding a vertical dimension to the system design. The silica chip is bonded onto the silicon chip, creating a vertical cascade that enables mode field transformation without compromising the horizontal integration density of the silicon photonic circuit.
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 approach significantly reduces mode mismatch and optical loss, enhancing coupling efficiency and compatibility with existing package technologies, while allowing for compact and cost-effective packaging solutions.
Implementation Method 1
optical diffraction grating in the same plane of the chip
Data Source
AI summary
Embodiments are provided for an optical coupler created by bonded photonic chip coupler for Silicon-on-Insulator (SOI) chip-fiber coupling. System and apparatus embodiments for a bonded photonic chip coupler for SOI chip-fiber coupling provide for reduced mismatch between fiber and chip, increased coupling efficiency, and lower photonics device insertion loss. In an embodiment, an optical coupler for coupling a photonics chip to an optical fiber includes a photonic chip comprising a nano-sized photonic waveguide, photonic optical diffraction surface grating, and a first cladding covering the photonic waveguide and the photonic grating; and an optical coupling chip comprising a micron-sized coupling waveguide and a coupling optical diffraction surface grating embedded in a first coupling cladding and on a second coupling cladding, wherein the first coupling cladding is connected to the first cladding, wherein the optical coupling chip is configured to couple to light transmitted between the photonic chip and an optical fiber.