Integrated Optical Coupler Grating for Multimode Fiber
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Solution Overview
Problem
Current fiber-optic systems face challenges in efficiently coupling light into and out of space-division multiplexed fibers, particularly due to the complexity and cost of existing solutions, and the inefficiency in generating desired fiber modes with grating couplers, which often result in power loss or crosstalk.
Innovation Solution
An integrated optical coupler device with a lateral grating structure that converts waveguide modes into fiber modes or vice versa, allowing for efficient coupling of different fiber modes into a multimode fiber without requiring a large fiber core, and is simple and inexpensive to produce, using a substrate-based design with a conductor pair and a coupling grating that can operate in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If free-space coupling devices are used to couple multiple fibers, then coupling efficiency is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple coupling functions into a single integrated optical waveguide structure with a shared grating coupler. Instead of using separate free-space coupling devices for each fiber, the invention merges all coupling operations into one compact integrated circuit that handles multiple input/output waveguides simultaneously, thereby maintaining high coupling efficiency while dramatically reducing device complexity
Solution Approach 2:
The integrated optical coupler device performs multiple functions within a single structure: it couples light between multiple waveguide modes and multiple fiber modes, supports both TE and TM polarizations, and enables bidirectional coupling. This multi-functionality eliminates the need for separate specialized coupling devices for each function, reducing overall system complexity while maintaining efficiency
2Adaptability or versatility
If multiple 2D grating couplers are arranged to generate multiple fiber modes, then mode generation capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges the functionality of multiple separate 2D grating couplers into a single integrated grating structure. This unified grating coupler handles all mode generation tasks simultaneously, eliminating the need for precise alignment between multiple independent gratings. The integrated design maintains the ability to generate multiple fiber modes while significantly reducing manufacturing precision requirements
Solution Approach 2:
The integrated grating coupler structure is designed to automatically achieve the correct phase and amplitude relationships for generating desired fiber modes through its inherent geometry and material properties. The structure self-configures the necessary conditions for mode generation without requiring external alignment adjustments or complex control mechanisms, thereby reducing manufacturing precision demands
3Adaptability or versatility
If large fiber core diameter is used to accommodate multiple modes, then mode coupling capability is improved, but fiber propagation properties deteriorate
Solution Approach 1:
The patent transitions from solving the mode coupling problem in the spatial domain (large fiber core) to solving it in the waveguide mode domain. By using an integrated optical circuit with multiple waveguide modes that couple to different fiber modes, the invention enables multi-mode coupling while maintaining a standard fiber core diameter, thus preserving favorable propagation properties
Solution Approach 2:
The integrated optical waveguide structure acts as an intermediary between the standard single-mode fiber and the multimode fiber. It provides the necessary mode transformation functionality without requiring modification of the fiber core, thereby maintaining good propagation properties while achieving versatile mode coupling capability
4Device complexity
If integrated optical circuits are used for coupling, then device complexity is reduced, but chip area requirements increase
Solution Approach 1:
The patent implements a compact integrated optical circuit design where multiple waveguides and grating structures are nested within a small chip area. The waveguides are arranged in a space-efficient manner, and the grating coupler utilizes the available area optimally to provide multiple coupling functions simultaneously, thereby reducing chip area requirements while maintaining low device complexity
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
The device achieves high-efficiency coupling of various fiber modes with reduced requirements for phase alignment, enabling cost-effective and efficient data transmission in multimode fibers, while maintaining simplicity in design and production.
Implementation Method 1
an integrated optical coupling grating extending in lateral directions parallel to the substrate surface and which, by diffraction at its grating structures, depending on the coupling direction, either converts electromagnetic waves, guided parallel to the substrate surface, of at least two waveguide modes of integrated optical waveguides into fiber modes
Data Source
AI summary
An integrated optical coupler device comprising, on a substrate surface: an integrated optical coupling grating extending in lateral directions parallel to the substrate surface and which, by diffraction at its grating structures, either converts electromagnetic waves, guided parallel to the substrate surface, of at least two waveguide modes of integrated optical waveguides into fiber modes propagating perpendicularly to the substrate surface, or converts electromagnetic waves, propagating perpendicularly to the substrate surface, of a fiber mode into electromagnetic waves, propagating parallel to the substrate surface, of at least two waveguide modes, and a first conductor pair, connected to the coupling grating and formed by a first and a second integrated optical waveguide, through which, in mutually opposite first and second directions parallel to the substrate surface, electromagnetic waves of at least two waveguide modes can be conducted to the coupling grating or can be conducted away from the coupling grating.