Silicon Depletion Modulator Slab Doping
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Solution Overview
Problem
Contemporary silicon depletion modulators face a trade-off between optical absorption loss and modulation bandwidth, with higher doping levels improving modulation efficiency but increasing absorption loss, and lower doping levels reducing absorption loss but compromising bandwidth.
Innovation Solution
Enhancing doping levels in slab regions between the waveguide core and contact areas, while maintaining lower doping levels in the waveguide core, to reduce optical absorption loss and improve modulation bandwidth without sacrificing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher doping levels are used in the waveguide core region, then modulation efficiency is improved, but optical absorption loss increases
Solution Approach 1:
The patent applies different doping levels to different regions of the waveguide structure. Specifically, the slab regions are doped at higher levels (1E18 to 1E20 atoms/cm³) while the waveguide core regions maintain lower doping levels (1E16 to 1E18 atoms/cm³). This local differentiation allows the slab regions to provide efficient carrier depletion for modulation while the core regions minimize optical absorption loss, thereby resolving the contradiction between modulation efficiency and optical absorption loss.
2Loss of energy
If lower doping levels are used in the waveguide core region, then optical absorption loss is reduced, but modulation bandwidth is compromised
Solution Approach 1:
The patent implements spatially varying doping concentrations where slab regions have higher doping levels (1E18 to 1E20 atoms/cm³) to ensure adequate carrier depletion and maintain modulation bandwidth, while waveguide core regions have lower doping levels (1E16 to 1E18 atoms/cm³) to minimize optical absorption loss. This local quality differentiation resolves the contradiction by assigning different doping characteristics to different functional regions.
Solution Approach 2:
The waveguide structure is segmented into distinct functional regions: slab regions and waveguide core regions. Each segment is independently doped to optimize its specific function. The slab regions are segmented as separate doping zones with higher doping levels to support bandwidth requirements, while core regions are segmented with lower doping levels to reduce loss, thereby resolving the bandwidth-loss contradiction through structural segmentation.
3Reliability
If higher doping levels are used throughout the structure, then series resistance is reduced, but optical absorption loss increases
Solution Approach 1:
The patent applies higher doping levels specifically to the slab regions (1E18 to 1E20 atoms/cm³) where carrier depletion occurs, which reduces series resistance in the modulation-active regions. The waveguide core regions maintain lower doping levels (1E16 to 1E18 atoms/cm³) to minimize optical absorption loss. This localized approach to resistance reduction resolves the contradiction between series resistance and optical absorption loss.
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 approach results in lower optical absorption loss and improved modulation bandwidth, with reduced series resistance and minimal additional loss, while maintaining modulation efficiency, especially at high bandwidth settings.
Implementation Method 1
silicon carrier-depletion modulators having an enhanced doping in at least part of slab regions between waveguide core and contact areas
Implementation Method 2
when an electrical voltage is applied to the contact electrode regions, the refractive index and absorption coefficient of the waveguide core region will be changed
Data Source
AI summary
Disclosed herein are methods, structures, and devices for a silicon carrier-depletion based modulator with enhanced doping in at least part of slab regions between waveguide core and contact areas. Compared to prior designs, this modulator exhibits lower optical absorption loss and better modulation bandwidth without sacrificing the modulation efficiency when operating at comparable bandwidth settings.