Plasmon Shield for TAMR Optical Spot Reduction
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Solution Overview
Problem
Current thermally assisted magnetic recording (TAMR) technologies face challenges in achieving a small enough optical spot size for high recording density due to limitations in edge plasmon generator tip radius and alignment, which affects the thermal and magnetic field gradients necessary for efficient data storage.
Innovation Solution
Incorporating a plasmon shield between the waveguide and edge plasmon generator in a triangular design, made of noble metals with a thin skin depth, to focus the optical spot more precisely on the magnetic medium, maintaining the edge plasmon mode and enhancing optical efficiency without scaling down the tip size or changing its angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the tip radius of the edge plasmon generator is reduced to achieve smaller optical spot size, then the optical spot size decreases, but the manufacturing difficulty increases significantly
Solution Approach 1:
A plasmon shield is introduced as an intermediary component between the waveguide and the edge plasmon generator. This shield, made of noble metal with thin skin depth, focuses the optical spot without requiring the EPG tip to be scaled down, thereby maintaining manufacturability while achieving smaller spot size
Solution Approach 2:
The invention changes the optical parameters by introducing a plasmon shield with specific material properties (noble metal, thin skin depth) and geometric configuration. This allows optical spot size reduction through field redistribution rather than through geometric scaling of the EPG tip
2Shape
If the tip angle of the edge plasmon generator is changed to optimize optical spot shape, then the optical spot distribution improves, but the alignment precision with magnetic field gradient becomes more difficult to achieve
Solution Approach 1:
The plasmon shield acts as a mediator that decouples the optical spot shaping function from the EPG tip geometry. By placing the shield between the waveguide and EPG, the optical field can be shaped independently of the tip angle, making alignment with the magnetic field gradient more straightforward
Solution Approach 2:
The optical field control function is segmented into two independent components: the EPG tip generates the plasmon mode, and the plasmon shield shapes and focuses the optical spot. This segmentation allows independent optimization of spot shape without compromising alignment precision
3Device complexity
If a conventional edge plasmon generator is used without a plasmon shield, then the structure is simpler, but the optical spot size is too large for high recording density
Solution Approach 1:
A plasmon shield is introduced as an intermediary component between the waveguide and the edge plasmon generator. This shield, made of noble metal with thin skin depth, focuses the optical spot without requiring the EPG tip to be scaled down, thereby maintaining manufacturability while achieving smaller spot size
Solution Approach 2:
The invention changes the optical parameters by introducing a plasmon shield with specific material properties (noble metal, thin skin depth) and geometric configuration. This allows optical spot size reduction through field redistribution rather than through geometric scaling of the EPG tip
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 plasmon shield significantly reduces the optical spot size in both cross-track and down-track directions, improving the thermal assist writing process and achieving higher areal density in TAMR, while maintaining optical efficiency and ease of manufacturing.
Implementation Method 1
The local confinement of the edge plasmon mode 7 is determined by the angle and radius of the triangle corner... the optical energy is confined around the tip of the EPG thereby forming a so-called edge plasmon mode
Implementation Method 2
optical power from a light source is converted into localized heating in a recording medium during a write process to temporarily reduce the field needed to switch the magnetizations of the medium grains
Implementation Method 3
TAMR involves raising the temperature of a small region of the magnetic medium to near its Curie temperature where both of its coercivity and anisotropy are significantly reduced
Data Source
AI summary
A TAMR head is disclosed with a triangular shaped plasmon antenna covered on two sides with a plasmon layer that generates an edge plasmon mode along a vertex of the two plasmon sides formed opposite a main pole layer. A plasmon shield (PS) is formed along the ABS and opposite the vertex to confine an electric field from the edge plasmon mode within a small radius of the edge plasmon tip thereby reducing the optical spot size on the magnetic medium and enhancing writability. An end of a waveguide used to direct input electromagnetic radiation to the plasmon antenna adjoins a PS side opposite the ABS. In one embodiment, a magnetic shield may be formed along the ABS and adjoins the PS so that a first PS section terminates at the ABS and faces the vertex while a second PS section is formed between the magnetic shield and waveguide end.