Waveguide Mode Converter for HAMR Write Heads
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Solution Overview
Problem
Current write heads for magnetic recording media face challenges in efficiently redirecting light from a fundamental transverse electric (TE00) mode to a higher-order (TE10) mode and directing surface plasmons to the recording medium, limiting data writing efficiency.
Innovation Solution
A waveguide core with a curved section and a branched portion is used to convert light from a TE00 mode to a TE10 mode, which is then redirected normal to the media-facing surface, coupled with a near-field transducer to direct surface plasmons to the recording medium, enhancing mode conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional waveguide structure is used to redirect light from TE00 mode to TE10 mode, then the device structure is simple, but the mode conversion efficiency is insufficient
Solution Approach 1:
The waveguide incorporates a curved section with specifically designed curvature radius to enable efficient mode conversion from TE00 to TE10. The curvature geometry transforms the light propagation path and facilitates the mode transition, achieving high conversion efficiency while maintaining structural feasibility
Solution Approach 2:
The waveguide is divided into distinct functional sections: a straight section for light input, a curved section for mode conversion, and another straight section for light output. This segmentation allows each section to be optimized for its specific function, with the curved section specifically designed to achieve efficient TE00 to TE10 mode conversion
2Productivity
If the waveguide redirects light normal to the media-facing surface, then the surface plasmon delivery is improved, but the device complexity increases
Solution Approach 1:
The curved section of the waveguide is designed with specific geometric parameters to redirect light normal to the media-facing surface. This curvature enables the light to follow a bent path that culminates in perpendicular incidence on the media surface, optimizing surface plasmon coupling while integrating smoothly into the overall device structure
3Reliability
If a branched portion is added to convert light to higher-order mode, then the mode conversion efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The branched portion is implemented as a distinct segment within the waveguide structure, separating the mode conversion function from the light transmission function. This segmented design allows the branched portion to be optimized specifically for TE00 to TE10 mode conversion while maintaining compatibility with standard waveguide fabrication processes
Solution Approach 2:
The curved section with specifically designed curvature radius serves as the mode conversion region, where the geometric curvature naturally facilitates the transition from fundamental TE00 mode to higher-order TE10 mode. The curvature geometry is optimized to achieve efficient conversion while remaining manufacturable
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 configuration significantly improves the efficiency of mode conversion and surface plasmon delivery, enabling more effective data writing by creating a hotspot on the recording medium for improved magnetic coercivity reduction and data storage.
Implementation Method 1
The waveguide core comprises a main portion having a curvature that changes linearly with curve length and is configured to receive light at an input, and a branched portion extending from a middle region of the main portion
Implementation Method 2
A near-field transducer at the media-facing surface is configured to receive the light at the TE10 mode from the waveguide and direct surface plasmons to a recording medium in response thereto
Implementation Method 3
The waveguide core comprises a first turn that receives the light in the crosstrack direction redirects the light to an opposite crosstrack direction and a second turn that redirects the light to a direction normal to a media-facing surface of the write head
Data Source
AI summary
A write head comprises a waveguide core configured to receive light emitted in a crosstrack direction from a light source at a fundamental transverse electric (TE00) mode. The waveguide core comprises a first turn that receives the light in the crosstrack direction redirects the light to an opposite crosstrack direction and a second turn that redirects the light to a direction normal to a media-facing surface of the write head. The waveguide core comprises a straight section that couples the first and second turns and a branched portion extending from the straight section. The branched portion is configured to convert the light to a higher-order (TE10) mode. A near-field transducer at the media-facing surface is configured to receive the light at the TE10 mode from the waveguide and directs surface plasmons to a recording medium in response thereto.