Phase Shifter Waveguide Pitch Reduction
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Solution Overview
Problem
In laser devices like LiDAR, the upper limit of light emission angle is limited by the pitch between waveguides due to the need to prevent light absorption by adjacent electrodes, resulting in reduced directivity control.
Innovation Solution
A phase shifter design with two waveguides per optical waveguide region, where p-type and n-type contact portions are alternately aligned to reduce the distance between waveguides and electrodes, minimizing optical loss through optical coupling and allowing for a smaller pitch, thereby increasing the light emission angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the distance between waveguides and electrodes is increased to prevent light absorption by adjacent electrodes, then light absorption loss is reduced, but the pitch between waveguides must be increased which limits the light emission angle
Solution Approach 1:
The patent introduces a vertical dimension by stacking p-type and n-type contact portions at different heights relative to the waveguide. The p-type contact portion is positioned closer to the waveguide while the n-type contact portion is positioned farther away, creating a vertical separation that allows horizontal closer spacing without increasing the pitch between waveguides.
Solution Approach 2:
The contact region is segmented into multiple contact portions (p-type and n-type) with different positions and functions. This segmentation allows each contact portion to serve a specific purpose: the p-type contact portion for carrier injection close to the waveguide and the n-type contact portion for voltage application at a distance, resolving the contradiction between close spacing and light absorption prevention.
2Length of moving object
If the pitch between waveguides is decreased to increase the light emission angle, then directivity control is improved, but light absorption by adjacent electrodes increases
Solution Approach 1:
By utilizing the vertical dimension to separate contact portions, the patent enables decreased horizontal pitch without increasing light absorption loss. The vertical stacking creates effective separation in the horizontal plane, allowing waveguides to be closer while preventing electrode-light interaction.
Solution Approach 2:
The p-type contact portion acts as an intermediary between the electrode and the waveguide. It is positioned close to the waveguide for efficient carrier injection but is separated from the n-type contact portion, preventing the electrode from directly absorbing light while still enabling electrical control.
3Length of moving object
If two waveguides are disposed at each optical waveguide region with alternately aligned contact portions, then the pitch between waveguides is reduced to increase light emission angle, but device complexity increases
Solution Approach 1:
Multiple contact portions (p-type and n-type) are merged into a single contact region that serves multiple functions: carrier injection, voltage application, and pitch reduction. This consolidation reduces device complexity compared to having separate contact regions for each waveguide while achieving the desired pitch reduction.
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 design enhances the upper limit of the light emission angle and improves modulation efficiency by reducing optical loss and power consumption while maintaining high-speed modulation.
Implementation Method 1
each of the waveguides accumulates carriers to modulate a phase of light for guiding propagation of the light
Implementation Method 2
a phase shifter may be adopted for adjusting an optical phase by changing a refractive index of each of the waveguides
Data Source
AI summary
A phase shifter includes a substrate, waveguides and a wiring portion. The substrate includes optical waveguide regions and contact regions. Each contact region has contact portions. The waveguides are disposed at the substrate, and each of the waveguides accumulates carriers to modulate a phase of light for guiding propagation of the light. The wiring portion electrically connects each of the waveguides and each of the contact portions. Each of the contact portions connecting each of the waveguides to a corresponding one of electrodes to inject the carriers into each of the waveguides. Each of the waveguides has a lengthwise direction defined as a first direction, and a direction that is perpendicular to the first direction and is parallel to a surface of the substrate is defined as a second direction. The optical waveguide regions and the contact regions are disposed to be alternately aligned along the second direction.