Curved-Edge Waveguide for HAMR Mode Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) devices face limitations in areal data density due to superparamagnetic effects, and existing technologies struggle to efficiently convert light from a transverse electric (TE) mode to a transverse magnetic (TM) mode for effective energy delivery to magnetic media.
Innovation Solution
A layered waveguide system is employed to convert TE mode light into TM mode light, featuring a first layer tapering in width and a second layer with increasing cross-sectional area along the light propagation direction, with a nonlinear interface between the layers, such as a curved design, to achieve polarization mode rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional waveguide is used to deliver light to the magnetic media, then the structure is simple, but the light mode cannot be effectively converted from TE to TM for efficient energy delivery
Solution Approach 1:
The waveguide is divided into multiple layers with different refractive indices and cross-sectional areas. The first layer has a smaller cross-sectional area while the second layer has a larger cross-sectional area, creating distinct regions that facilitate progressive mode conversion from TE to TM polarization while maintaining structural manageability
Solution Approach 2:
Different sections of the waveguide are designed with locally optimized properties - the first layer region provides initial mode coupling with a smaller cross-section, while the second layer region provides final mode conversion with a larger cross-section. This local differentiation enables effective TE to TM conversion at specific locations within the waveguide structure
2Reliability
If the waveguide cross-sectional area increases along the light propagation direction, then mode conversion from TE to TM is achieved, but the device length increases
Solution Approach 1:
Instead of achieving mode conversion through a long linear path, the patent utilizes the cross-sectional dimension by varying the area between two layers. The interface between layers with different cross-sectional areas enables compact mode conversion in a shorter distance, effectively using spatial dimensionality to reduce device length while maintaining conversion efficiency
3Reliability
If a curved interface is used between waveguide layers, then mode conversion efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The interface between the first and second waveguide layers is designed with a curved geometry rather than a sharp angle or flat surface. This curved interface gradually transitions the mode field distribution, reducing scattering losses and improving mode conversion efficiency. The curvature is optimized to balance performance improvement with manufacturability through standard fabrication processes
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 solution enables efficient energy delivery to magnetic media, overcoming superparamagnetic limitations and enhancing areal data density by effectively converting light polarization, thereby improving the performance of HAMR devices.
Implementation Method 1
The layered waveguide is configured to receive light from the input coupler in a transverse electric (TE) mode and deliver the light to the NFT in a transverse magnetic (TM) mode
Implementation Method 2
achieve polarization mode rotation
Data Source
AI summary
An apparatus includes an input coupler configured to receive light excited by a light source. A near-field transducer (NFT) is positioned at a media-facing surface of a write head. A layered waveguide is positioned between the input coupler and the NFT and configured to receive the light output from the input coupler in a transverse electric (TE) mode and deliver the light to the NFT in a transverse magnetic (TM) mode. The layered waveguide comprises a first layer extending along a light-propagation direction. The first layer is configured to receive light from the input coupler. The first layer tapers from a first cross track width to a second cross track width where the second cross track width is narrower than the first cross track width. The layered waveguide includes a second layer that is disposed on the first layer. The second layer has a cross sectional area in a plane perpendicular to the light propagation direction that increases along the light propagation direction. The cross sectional area of the second layer is smaller proximate to the input coupler and larger proximate to the NFT. The layered waveguide includes an interface between the first layer and the second layer, the interface comprises a curve.