Plasmon Shield Reduces Optical Spot Size in TAMR Heads
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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 the TAMR write head, made of noble metals with a thin skin depth, to focus the optical spot more precisely on the magnetic medium without reducing the tip size or altering the tip angle, thereby enhancing optical efficiency and reducing the optical spot size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
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. The shield, made of noble metal with thin skin depth, focuses the optical spot without requiring reduction of the generator tip radius, thus achieving small spot size while maintaining manufacturability of the tip
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 reduction of the tip, resolving the manufacturing contradiction
2Manufacturing precision
If the tip angle of the edge plasmon generator is altered to reduce optical spot size, then the optical spot size decreases, but the alignment precision with magnetic field gradient deteriorates
Solution Approach 1:
The plasmon shield serves as a mediator that decouples the optical focusing function from the generator tip geometry. By placing the shield between the waveguide and generator, it focuses the optical spot independently of the tip angle, thereby maintaining alignment precision while achieving smaller spot size
3Manufacturing precision
If the edge plasmon generator tip size is reduced to achieve smaller optical spot, then the optical spot size decreases, but the optical efficiency deteriorates
Solution Approach 1:
The plasmon shield acts as an optical intermediary that enhances field concentration without requiring tip size reduction. The shield's noble metal composition and thin skin depth enable efficient optical field redistribution, maintaining optical efficiency while achieving smaller spot size through field focusing rather than geometric reduction
Solution Approach 2:
The invention changes the optical field distribution parameters by introducing the plasmon shield. This allows the system to achieve smaller spot size through field concentration mechanisms rather than reducing the physical tip dimensions, thereby preserving optical efficiency
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 effectively reduces the optical spot size in both cross-track and down-track directions, improving the thermal assist writing process and increasing areal density in TAMR, while maintaining optical efficiency and facilitating easier manufacturing of the edge plasmon generator tip.
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 transformed to plasmon energy, either with local plasmon excitation in the PA or with energy transmission along the PG, it is concentrated at the medium location where heating is desired
Implementation Method 2
optical power from a light source is converted into localized heating in a recording medium during a write process... optical energy is transformed to plasmon energy... it is concentrated at the medium location where heating is desired
Implementation Method 3
The plasmon shield is made of a noble metal with a thin skin depth to shunt the electric field and maintain the edge plasmon mode in the vicinity of the EPG vertex
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.