Hybrid Silicon Photonic Modulator for High-Speed Operation
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Solution Overview
Problem
Silicon-based optical modulators have limited operating speeds due to high capacitance in forward bias operation, while III-V semiconductor modulators face tradeoffs between electro-optic efficiency and optical propagation loss, and silicon/III-V photonic integration is limited by reliance on p-type dopants increasing optical and microwave losses.
Innovation Solution
A hybrid silicon photonic modulator combining silicon and III-V semiconductor regions with overlapping optical waveguides, where the refractive index changes based on applied electrical differences, using complementary dopants and quantum wells for enhanced electro-optic efficiency, and a dielectric layer to prevent carrier transport and reduce capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silicon-based modulators use forward bias operation, then electro-optic modulation is achieved, but operating speed is limited due to high capacitance
Solution Approach 1:
The modulator is divided into separate silicon and III-V semiconductor regions, each performing specific functions. The silicon region handles waveguiding and passive functions, while the III-V region provides active electro-optic modulation, allowing the system to achieve high speed without the capacitance issues of forward-biased silicon junctions
Solution Approach 2:
The patent combines silicon and III-V semiconductor materials in a hybrid structure. This composite approach leverages the advantages of both materials: silicon's excellent waveguiding properties and III-V's high electro-optic efficiency, achieving both high speed and low capacitance simultaneously
2Productivity
If III-V semiconductor modulators use PIN junction to confine electric field, then electro-optic efficiency is improved, but optical and microwave losses increase due to p-type dopants
Solution Approach 1:
The patent applies different material properties to different regions: the III-V semiconductor region uses n-type doping (without p-type dopants) to achieve high electro-optic efficiency while avoiding the losses associated with p-type dopants. The silicon region provides waveguiding functions, creating a localized optimization of material properties where each region performs its specific function without compromising the other
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary between the silicon and III-V semiconductor regions. This dielectric layer prevents carrier transport between the two materials, isolating the III-V region from the silicon region and allowing the III-V material to operate with n-type doping alone, thereby maintaining high electro-optic efficiency while avoiding p-type dopant losses
3Productivity
If silicon-based modulators scale waveguide dimensions to sub-micron geometries, then electro-optic efficiency is improved, but optical confinement degrades
Solution Approach 1:
The hybrid structure combines silicon and III-V semiconductor materials with different refractive indices and optical properties. This composite material approach enables the maintenance of optical confinement at sub-micron dimensions by leveraging the complementary properties of both materials, where the silicon region provides structural stability and the III-V region provides enhanced electro-optic response without compromising optical confinement
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
Enables high-speed operation with low drive voltage and short device length, while minimizing optical and microwave losses by leveraging the high electro-optic efficiency of III-V materials and the processing advantages of silicon, achieving efficient light modulation and absorption.
Implementation Method 1
The efficiency of an optical modulator (i.e. the aspects of the drive voltage or power requirement of the optical modulator) is fundamentally determined by the electro-optic (EO) materials used to construct the modulator. III-V semiconductor based optical modulators rely on field based modulation that may achieve up to 50 times the efficiency of Si based modulators at a given length.
Implementation Method 2
a dielectric layer to prevent carrier transport and reduce capacitance
Implementation Method 3
overlapping optical waveguides, where the refractive index changes based on applied electrical differences
Implementation Method 4
using complementary dopants and quantum wells for enhanced electro-optic efficiency
Data Source
AI summary
An electro-optic modulator comprising a first region of silicon material and a second region of non-silicon material. The second region may at least partially overlap the first region to create a lateral overlap region. An optical waveguide of the modulator may be included in the lateral overlap region and comprise of both the silicon and the non-silicon material. The refractive index of at least one of the silicon material and the non-silicon material within the optical waveguide may change based on an electrical difference applied between electrical contacts of the modulator.