Interfering Plasmonic Metal Bars for EAMR Near Field Transducer
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Solution Overview
Problem
Inefficiencies in near field transducers (NFTs) used in Energy Assisted Magnetic Recording (EAMR) and Heat Assisted Magnetic Recording (HAMR) systems lead to high power demands and reduced service lifetime due to the mechanical susceptibility of high-quality plasmonic metals, which are prone to damage from thermal and mechanical stresses.
Innovation Solution
The use of wider plasmonic metal bars with optimized configurations, such as two interfering plasmonic metal bar elements and a plasmonic metal cap, to enhance energy delivery efficiency and robustness, allowing for improved focus of the heating spot on the magnetic storage disk while withstanding mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-quality plasmonic metals with fine (nano-sized) features are used in the NFT, then the light focusing capability and energy delivery efficiency are improved, but the mechanical robustness deteriorates and susceptibility to thermal or mechanical stress damage increases
Solution Approach 1:
The NFT is divided into multiple functional regions: a robust substrate layer providing mechanical support, and separate plasmonic metal bar elements (with widths of 50-200 nm) positioned above the substrate that perform the light focusing function. This segmentation allows the substrate to withstand mechanical stresses while the thinner plasmonic elements optimize optical performance.
Solution Approach 2:
The NFT employs a composite structure combining a mechanically robust substrate material (such as silicon nitride or diamond-like carbon) with plasmonic metal layers (such as aluminum or aluminum alloy). This composite construction provides both the mechanical strength needed for EAMR head durability and the plasmonic properties required for efficient near-field light focusing.
2Manufacturing precision
If the plasmonic metal features are made thinner to achieve better light focusing, then the nano-focusing capability is improved, but the mechanical robustness and resistance to stress damage worsen
Solution Approach 1:
The NFT is divided into multiple functional regions: a robust substrate layer providing mechanical support, and separate plasmonic metal bar elements (with widths of 50-200 nm) positioned above the substrate that perform the light focusing function. This segmentation allows the substrate to withstand mechanical stresses while the thinner plasmonic elements optimize optical performance.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the robust substrate and the thin plasmonic metal bars. This dielectric mediator allows the thin plasmonic elements to achieve superior light focusing while the substrate provides mechanical strength, with the dielectric layer facilitating stress isolation and optical coupling.
3Temperature
If higher laser power is used to compensate for NFT inefficiencies, then the heating effect on the magnetic disk is improved, but parasitic heating of the EAMR head increases and system reliability deteriorates
Solution Approach 1:
The NFT design enables more efficient energy transfer, allowing the system to achieve the required heating effect with lower peak laser power. The optimized plasmonic structure concentrates light energy more effectively, reducing the need for high power operation and thereby minimizing parasitic heating effects.
Solution Approach 2:
By changing the geometric parameters of the plasmonic metal bars (width, length, spacing) and optimizing the NFT structure, the energy transfer efficiency is improved. This allows the system to achieve the same heating effect with lower input power, reducing parasitic heating and improving overall system reliability.
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 results in lower laser power requirements, reduced parasitic heating, and extended service life of the EAMR/HAMR device by achieving higher electrical field magnitudes and improved energy transfer efficiency.
Implementation Method 1
In an NFT, plasmonic metal can be used to form SPPs (surface plasmon polaritons), which carry out the nano-focusing function beyond the light's diffraction limit.
Implementation Method 2
The NFT couples the diffraction limited light from waveguide (WG), then further focuses the light field energy beyond diffraction limit down to a highly concentrated (nano-sized) near-field media heating spot
Implementation Method 3
The NFT couples the diffraction limited light from waveguide (WG), then further focuses the light field energy beyond diffraction limit down to a highly concentrated (nano-sized) near-field media heating spot enabling EAMR/HAMR writing to the magnetic storage disk
Implementation Method 4
The magnetic properties of the media may be softened when writing to the disk to assist changing the bit state. Energy Assisted Magnetic Recording (EAMR) device or Heat Assisted Magnetic Recording (HAMR) technology provides heat that is focused on a nano-sized bit region when writing onto a magnetic storage disk, which achieves the magnetic softening.
Data Source
AI summary
An apparatus for energy assisted magnetic recording of a storage disk include a plurality of dielectric waveguide cores configured to direct received incident light energy to a target, and a near field transducer (NFT) configured to focus light energy received from the plurality of waveguide cores and to transmit the focused light energy onto the storage disk surface to generate a heating spot on the storage disk. The NFT includes a plurality of propagating surface plasmon polariton (PSPP) elements that are energized by the light energy from the waveguide cores. Each of the PSPP elements has a plasmonic metal bar disposed above a single waveguide core in a longitudinal alignment. Each metal bar has a width at least twice the width of the heating spot generated on the storage disk.