Optically Opaque Overlay with Periodic Structures for HAMR Waveguide
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Solution Overview
Problem
Laser-induced protrusion at the air-bearing surface of heat-assisted magnetic recording (HAMR) sliders reduces areal density and reliability due to thermal expansion and excessive heating, affecting both writer and reader performance.
Innovation Solution
Incorporating an optically opaque overlay with periodic structures at the outer boundary of the optical waveguide to organize stray light for absorption, enhancing heat dissipation and reducing specular reflection, thereby minimizing optically generated protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an optically opaque overlay is added to the waveguide, then heat dissipation is enhanced and specular reflection is reduced, but device complexity increases
Solution Approach 1:
The patent converts the harmful stray light that causes thermal expansion and protrusion into a beneficial effect by using an optically opaque overlay with periodic structures. The overlay absorbs the stray light and converts it to heat, which is then dissipated through the substrate, preventing the harmful thermal effects while utilizing the optical energy constructively.
Solution Approach 2:
The optically opaque overlay with periodic structures is integrated within the existing waveguide structure, nesting the light-absorbing functionality within the optical path. The periodic structures are embedded in the overlay layer, creating a multi-functional integrated component that addresses multiple issues simultaneously.
2Reliability
If periodic structures are added to organize stray light, then laser-induced protrusion is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs periodic structures with specific geometric parameters (period, depth, width) that are optimized to achieve effective stray light organization. By carefully controlling these parameters, the structure creates constructive interference patterns that direct stray light into the opaque overlay, reducing protrusion while maintaining manufacturability through parameter optimization.
Solution Approach 2:
The periodic structures are applied locally at specific regions of the waveguide where stray light generation is most problematic. Rather than requiring precision across the entire device, the solution targets specific zones with localized periodic patterning, reducing the overall manufacturing precision burden while maintaining effectiveness.
3Stability of the object's composition
If the optically opaque overlay absorbs more stray light, then thermal expansion is reduced, but the overlay may generate heat that affects nearby components
Solution Approach 1:
The patent extracts the heat generated by the optically opaque overlay from the sensitive regions by designing the overlay and periodic structures to direct absorbed optical energy away from the NFT and write pole. The heat is channeled into the substrate and dissipated in regions that do not affect the critical recording components, separating the heat generation zone from the sensitive operational zones.
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 solution achieves a significant reduction in laser-induced writer and reader protrusion, enhancing the stability and reliability of HAMR sliders by dissipating heat effectively and reducing thermal expansion, resulting in improved areal density and performance.
Implementation Method 1
Periodic structures are disposed on a surface of the optically opaque overlay facing the waveguide. The periodic structures are configured to organize stray light emanating from the waveguide for absorption by the optically opaque overlay
Implementation Method 2
The periodic structures are configured to organize stray light emanating from the waveguide for absorption by the optically opaque overlay
Implementation Method 3
An optically opaque overlay is disposed on or adjacent one or both of the first and second major surfaces of the optical waveguide
Implementation Method 4
enhancing heat dissipation and reducing specular reflection, thereby minimizing optically generated protrusion
Implementation Method 5
an optical waveguide configured to receive light from a light source and couple the light to the NFT
Implementation Method 6
near-field transducer (NFT) proximate the write pole, and an optical waveguide configured to receive light from a light source and couple the light to the NFT
Data Source
AI summary
An apparatus comprises a slider having an air bearing surface and is configured for heat-assisted magnetic recording. The slider comprises a write pole, a near-field transducer (NFT) proximate the write pole, and an optical waveguide configured to receive light from a light source and couple the light to the NFT. The optical waveguide comprises first and second opposing major surfaces and opposing first and second edges connected to the first and second major surfaces. An optically opaque overlay is disposed on or adjacent one or both of the first and second major surfaces of the optical waveguide. Periodic structures are disposed on a surface of the optically opaque overlay facing the waveguide. The periodic structures are configured to organize stray light emanating from the waveguide for absorption by the optically opaque overlay.