Waveguide Polarization Rotator Splitter for HAMR
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Solution Overview
Problem
Current heat-assisted magnetic recording (HAMR) technologies face challenges in efficiently converting transverse electric (TE) polarized light to transverse magnetic (TM) polarized light due to imperfect polarization rotators, leading to residual TE mode in the light path which degrades recording performance and increases thermal background.
Innovation Solution
A polarization rotator and splitter system that rotates TE mode to TM mode using a channel waveguide section and a splitter waveguide separated by a dielectric gap, effectively removing residual TE mode through birefringence and mode index differences, optimizing light delivery for near-field transducers in HAMR devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarization rotator is used to convert TE mode to TM mode, then the conversion efficiency is improved, but residual TE mode remains in the light path which degrades recording performance
Solution Approach 1:
The waveguide is segmented into multiple sections with different polarization rotation characteristics. The first waveguide section provides initial TE to TM conversion, while the second waveguide section with different dimensions provides additional rotation to complete the polarization conversion, thereby reducing residual TE mode.
Solution Approach 2:
Different sections of the waveguide are designed with different local properties (different width-to-height ratios) to provide different polarization rotation characteristics. The first section has a first width-to-height ratio optimized for initial conversion, while the second section has a second width-to-height ratio optimized for completing the rotation, with each section contributing differently to the overall polarization conversion.
2Reliability
If a polarization rotator is used to convert TE mode to TM mode, then the conversion efficiency is improved, but thermal background increases
Solution Approach 1:
The polarization conversion process is segmented into two stages using two waveguide sections with different dimensions. This segmentation allows each section to contribute to the overall conversion efficiency, achieving more complete TE to TM mode conversion and thereby reducing thermal background generation.
Solution Approach 2:
The waveguide dimensions (width and height) are changed between the two sections to optimize the polarization rotation at each stage. The first waveguide section has dimensions optimized for initial TE to TM conversion, while the second section has different dimensions to complete the rotation, with the parameter changes enabling more efficient polarization conversion and reduced thermal background.
3Reliability
If a polarization rotator is used to convert TE mode to TM mode, then the conversion efficiency is improved, but device complexity increases
Solution Approach 1:
The two waveguide sections are merged into a single integrated waveguide structure that performs both polarization conversion stages sequentially. This merging approach achieves high polarization conversion efficiency while avoiding the need for separate discrete polarization conversion components, thereby limiting the increase in device complexity.
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 system achieves high efficiency in converting TE to TM mode, reducing thermal background and improving recording performance by removing over 90% of the residual TE mode while maintaining high TM mode transmission, thus enhancing data storage reliability.
Implementation Method 1
A polarization rotator rotates a portion of light received from an input surface to an orthogonal polarization
Implementation Method 2
A polarization splitter is coupled to the polarization rotator and includes a channel waveguide section that transmits the rotated portion of the light towards an output surface
Implementation Method 3
The splitter also includes a splitter waveguide separated from the channel waveguide section by a dielectric gap. The splitter waveguide couples an unrotated portion of the light away from a target region of the output surface
Data Source
AI summary
A polarization rotator rotates a portion of light received from an input surface to an orthogonal polarization. A polarization splitter is coupled to the polarization rotator and includes a channel waveguide section that transmits the rotated portion of the light towards an output surface. The splitter also includes a splitter waveguide separated from the channel waveguide section by a dielectric gap. The splitter waveguide couples an unrotated portion of the light away from a target region of the output surface.