On-Chip Polarizer Using Evanescently Coupled Waveguides
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Solution Overview
Problem
Conventional on-chip transverse electric (TE) and transverse magnetic (TM) polarizers require a large footprint due to the need for long waveguides to effectively filter out TE or TM polarized light, consuming significant chip area.
Innovation Solution
A photonic integrated circuit (PIC) chip with an on-chip polarizer design featuring two differently shaped waveguides at different design levels, where a first waveguide with an elongated main body and a spiral second waveguide are evanescently coupled, allowing for efficient filtering of light signals by attenuating unwanted polarized light as it passes from the outer end of the second waveguide toward its inner end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional waveguides with multiple turns are used to filter polarized light, then polarization filtering is achieved, but the chip area consumed is large
Solution Approach 1:
The patent introduces a vertical dimension by placing two waveguides at different design levels (first waveguide at one level, second waveguide at another level). This stacked configuration allows evanescent coupling between waveguides without requiring long horizontal paths, thereby reducing chip area while maintaining polarization filtering effectiveness.
Solution Approach 2:
The patent employs nested waveguide structures where the first and second waveguides are coupled in a nested manner through evanescent coupling. The light path in the first waveguide interacts with the second waveguide structure, allowing compact polarization filtering by nesting functional elements rather than using sequential long paths.
2Reliability
If long waveguides are used to filter TE or TM polarized light, then adequate filtering is achieved, but the device footprint is large
Solution Approach 1:
By transitioning from a single-level horizontal waveguide layout to a multi-level vertical stacking architecture, the patent achieves adequate filtering performance through evanescent coupling between levels. This dimensional change allows compact footprint by utilizing the vertical space above and below the substrate rather than expanding horizontally.
Solution Approach 2:
The patent segments the polarization filtering function into two separate waveguides at different levels, each with specific functions (first waveguide for transmitting desired polarization, second waveguide for attenuating unwanted polarization). This segmentation allows compact design by distributing filtering functions across multiple small components rather than using one long waveguide.
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 reduces the chip area required for polarization filtering by effectively passing desired polarized light through the main body of the first waveguide while attenuating unwanted polarized light, thereby minimizing the footprint of the polarizer.
Implementation Method 1
The outer end of the second waveguide can be evanescently coupled to the main body of the first waveguide
Implementation Method 2
The outer end of the second waveguide can be evanescently coupled to the main body of the first waveguide
Implementation Method 3
The outer end of the second waveguide can be evanescently coupled to the main body of the first waveguide
Data Source
AI summary
Disclosed are embodiments of an on-chip polarizer and of methods of forming the polarizer. The polarizer includes first and second waveguides with different shapes at different design levels above a substrate. The first waveguide has a main body between an input end and an output end. The second waveguide is spiral in shape with an inner end and with an outer end that is evanescently coupled to the main body of the first waveguide. Light signals, including first light signals with a first type polarization and second light signals with a second type polarity, are received at the input end of the first waveguide. The first waveguide passes the first light signals to the output end and passes at least some second light signals out the main body and into the outer end of the second waveguide. The second waveguide attenuates the received second light signals.