Graded-Index Lens for Multimode Optical Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical interconnect technologies face challenges in cost-effectively coupling small-scale optical devices for efficient data transmission, particularly in applications like personal computers, servers, and data centers, where high data rates are required.
Innovation Solution
The use of a graded-index lens with layers of increasing refractive index to focus multimode optical beams into smaller-dimensioned waveguides, achieving high coupling efficiency and enabling efficient data transmission by converting optical signals into electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard optical coupling methods are used to couple multimode light sources to smaller-dimensioned waveguides, then the device complexity is low, but the coupling efficiency is insufficient for high-rate data transmission
Solution Approach 1:
A graded-index lens is introduced as an intermediary optical element between the multimode light source and the smaller-dimensioned waveguide. This lens mediates the coupling by focusing the multimode light into the smaller waveguide core, achieving at least 70% coupling efficiency while maintaining compatibility with standard semiconductor fabrication processes
Solution Approach 2:
The refractive index of the lens material is specifically engineered to decrease from the center to the periphery (graded-index profile), creating a focusing effect that couples light efficiently. The lens is formed with a specific numerical aperture range (0.2 to 0.6) optimized for coupling multimode light to smaller waveguides, representing a parameter change approach to solve the coupling efficiency problem
2Reliability
If larger-dimensioned optical components are used to maintain coupling efficiency, then the coupling efficiency is improved, but the integration density on semiconductor chips decreases
Solution Approach 1:
The graded-index lens creates a localized focusing region with specific optical properties (refractive index gradient) that concentrates light into the smaller waveguide. This local quality enhancement allows efficient coupling without requiring large-dimensioned optical components, maintaining small footprint for chip integration
Solution Approach 2:
The lens is formed using composite material structures, specifically layers of silicon nitride with different refractive indices (e.g., SiN/SiO2/SiN layering) or silicon germanium alloys with varying germanium content. This composite approach enables the graded-index profile in a compact structure suitable for semiconductor chip integration
3Reliability
If complex optical coupling structures are implemented to achieve high coupling efficiency, then the coupling efficiency is improved, but the manufacturing cost and fabrication complexity increase
Solution Approach 1:
The mechanical alignment and positioning systems typically required for precise optical coupling are replaced by forming the graded-index lens directly on the semiconductor chip using standard fabrication processes. This substitution eliminates complex alignment mechanisms while achieving high coupling efficiency through the lens's inherent focusing property
Solution Approach 2:
The lens is fabricated using standard semiconductor processing techniques with controllable parameters (layer thickness, refractive index profiles, doping concentrations) that can be precisely adjusted during manufacturing. This allows optimization of coupling efficiency (at least 70%) while maintaining compatibility with existing fabrication infrastructure, avoiding the need for specialized or costly manufacturing processes
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 solution provides at least 70% coupling efficiency between multimode light sources and smaller-dimensioned waveguides, facilitating high-speed data transmission while being amenable to integration on semiconductor chips and fabrication using standard semiconductor processing techniques.
Implementation Method 1
a graded-index lens with layers of increasing refractive index to focus multimode optical beams into smaller-dimensioned waveguides
Data Source
AI summary
Embodiments of the invention provide optical lenses comprised of layers of material each having a different index of refraction from that of the other layers wherein the layers of material are arranged in order of increasing index of refraction. The lens region is capable of causing an optical beam that enters the lens region to be focused into an output beam that is smaller in at least one dimension. A waveguide is optically coupled to the optical lens and a photodetector is optically coupled to the waveguide. The optical lens is capable of being manufactured using semiconductor processing techniques and is capable of being integrated into an integrated circuit chip.