Subwavelength Mirrors for HAMR Head Durability
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Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) devices face wear and degradation issues due to high temperatures affecting optical components, leading to voiding and separation around the near-field transducer, which reduces the lifespan of the recording heads.
Innovation Solution
The use of subwavelength mirrors made from a combination of mechanically robust materials at the media-facing surface and plasmonic materials inside, with a liner to enhance durability and optical performance, focusing light onto the near-field transducer while blocking background light and improving thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperatures are used for heat-assisted magnetic recording, then recording density is improved, but optical components suffer wear and degradation leading to reduced lifespan
Solution Approach 1:
The patent segments the optical components into distinct functional zones: a waveguide for light delivery, a near-field transducer for heat generation, and subwavelength mirrors for light focusing. Each segment is optimized for its specific function and exposed to different thermal conditions, allowing the system to achieve high recording density while protecting critical components from excessive thermal damage.
Solution Approach 2:
The patent introduces an intermediary protective structure between the high-temperature recording zone and the optical components. This protective layer acts as a thermal barrier, allowing the near-field transducer to generate high temperatures for improved recording density while preventing direct thermal exposure to the waveguide and mirrors, thereby extending component lifespan.
2Measurement precision
If subwavelength mirrors are used to focus light, then optical performance is improved, but mechanical robustness is reduced due to use of plasmonic materials
Solution Approach 1:
The patent applies local quality by using different materials in different regions of the subwavelength mirrors. The portion facing the near-field transducer is made of mechanically robust material to withstand thermal and mechanical stress, while other regions use plasmonic materials optimized for optical performance. This spatial differentiation of material properties resolves the contradiction between mechanical strength and optical efficiency.
Solution Approach 2:
The patent employs composite material structures for the subwavelength mirrors, combining mechanically robust materials with plasmonic materials. This composite approach allows the mirrors to simultaneously achieve the mechanical strength needed for durability and the optical properties required for effective light focusing and concentration.
3Productivity
If laser current is increased to improve recording, then recording density is enhanced, but thermal damage to components increases
Solution Approach 1:
The patent replaces direct high-current laser heating with a more efficient optical-thermal conversion system. Subwavelength mirrors focus light into concentrated spots that generate heat more efficiently through optical resonance, achieving high recording density with lower overall laser current. This substitution of direct thermal heating with optically-mediated heating reduces thermal damage to components.
Solution Approach 2:
The patent utilizes phase transition phenomena in the plasmonic and dielectric materials of the subwavelength mirrors to enhance light absorption and heat generation at specific resonant frequencies. By operating at these resonant conditions, the system achieves efficient thermal conversion for high-density recording while minimizing the total laser current required, thereby reducing thermal damage to surrounding components.
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 increases the robustness and durability of the recording head, reducing wear and extending its lifespan by maintaining optimal optical performance and thermal gradients, thereby enhancing the recording density and reducing the required laser current.
Implementation Method 1
Two subwavelength focusing mirrors are at an end of the waveguide proximate the media-facing surface... The subwavelength mirrors are on opposite crosstrack sides of the near-field transducer... focusing light onto the near-field transducer
Implementation Method 2
Heat-assisted recording head... near-field transducer... improving thermal gradients
Data Source
AI summary
A recording head has a near-field transducer that extends a first distance away from a media-facing surface. Two subwavelength focusing mirrors are at an end of a waveguide proximate the media-facing surface and extend a second distance away from the media-facing surface that is less than the first distance. The subwavelength mirrors are on opposite crosstrack sides of the near-field transducer and separated from each other by a crosstrack gap. The subwavelength focusing mirrors each include a first material at the media-facing surface and a plasmonic material that covers an edge of the subwavelength focusing mirror that faces the near-field transducer. The first material is more mechanically robust than the plasmonic material.