Optical Bipolar Phase Shifter With Segmented Doping
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Solution Overview
Problem
Current optical phase shifters experience inefficiencies due to losses from doped impurities that are not controlled by voltage, leading to a tradeoff between phase shift and loss, and existing solutions are not optimal for achieving efficient and linear phase modulation.
Innovation Solution
An optical phase shifter with a substrate having at least one region with a first doping and two regions with a second doping, arranged in an alternating pattern perpendicular to the beam propagation direction, forming bi-junctions that extend parallel to the direction, allowing for efficient phase change and increased linearity with reduced voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doped impurities are used in the optical waveguide to enable phase modulation, then phase shift capability is achieved, but optical losses increase due to absorption by doped impurities
Solution Approach 1:
The optical waveguide is segmented into multiple doped regions with alternating doping types (first doped region between two second doped regions). This segmentation creates multiple depletion zones that can be independently controlled, allowing the optical mode to interact with voltage-controlled charge regions while minimizing interaction with static doped impurities that cause loss.
Solution Approach 2:
Different regions of the optical waveguide are assigned different doping characteristics. The first doped region and two second doped regions create localized depletion zones with specific charge distributions. This local quality variation enables the optical mode to experience phase modulation in specific regions while avoiding lossy regions with static doped impurities.
2Productivity
If the length of the semiconductor-semiconductor junction is increased to maximize overlap between optical mode and voltage-dependent charge region, then phase modulation efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of using a single long junction, the structure is divided into multiple shorter junction segments (first doped region between two second doped regions). This segmentation achieves the required total overlap length through multiple distributed interactions, improving efficiency while maintaining manageable junction lengths that are easier to manufacture with standard processes.
Solution Approach 2:
The doping structure is arranged in a specific spatial configuration where the first doped region is positioned between two second doped regions. This dimensional arrangement creates multiple overlap zones along the propagation direction, effectively increasing the total interaction length without requiring a single excessively long junction, thus improving efficiency while controlling complexity.
3Productivity
If multiple doped regions are introduced to improve phase shift efficiency, then modulation performance increases, but manufacturing precision requirements increase
Solution Approach 1:
The modulation function is distributed across multiple doped regions rather than requiring a single complex structure. The first doped region between two second doped regions creates multiple depletion zones that collectively achieve the required phase modulation. This segmentation provides manufacturing tolerance because the overall performance is the sum of multiple simpler, more tolerable junctions rather than one critical long junction.
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 solution enhances the efficiency and linearity of the optical phase shifter, enabling a complete 180° phase shift at lower voltages and reducing optical losses, thereby improving the overall performance of the device.
Implementation Method 1
The modulation of the charge density changes the refractive index of the silicon as a result of the free carrier effect (also known as the indirect electro-optical effect of silicon)
Implementation Method 2
When the charge density in the silicon increases, the photons that propagate or move through the silicon are more susceptible to an annihilation by the foreign atoms that bring about the doping. This is also referred to as an optical absorption loss
Data Source
AI summary
An optical phase shifter is described, which includes an optical waveguide which is realized in a substrate and has an optical conduction surface within the substrate, the optical conduction surface including at least a first region having a first doping and at least two second regions having a second doping that differs from the first doping. The first region is situated between the two second regions.