Thermally-Assisted Magnetic Recording Head Plasmon Generator Collision Prevention
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Solution Overview
Problem
In thermally-assisted magnetic recording systems, the plasmon generator can collide with the magnetic recording medium due to overheating, leading to degradation in near-field light generation and recording performance.
Innovation Solution
A light-absorbing protrusion layer is introduced on the leading side of the plasmon generator, with a width ratio to the waveguide within the range of 2/3 to 55/3, allowing thermal expansion to protrude and reduce the likelihood of collision, ensuring near-field light generation capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light intensity is increased to improve near-field light generation, then the plasmon generator generates more heat and protrudes toward the magnetic recording medium, but this causes collision between the plasmon generator and the magnetic recording medium
Solution Approach 1:
A light-absorbing layer is introduced as an intermediary component between the waveguide and the plasmon generator. This layer absorbs excess light energy and converts it to heat, which causes thermal expansion and protrusion of the light-absorbing layer itself rather than the plasmon generator. This mediator structure prevents direct heat generation in the plasmon generator, thereby avoiding collision with the magnetic recording medium while still enabling near-field light generation.
Solution Approach 2:
The invention changes the thermal expansion parameter distribution by introducing a light-absorbing layer with specific thermal properties. When light is absorbed, this layer undergoes thermal expansion (parameter change) that causes it to protrude toward the magnetic recording medium. This parameter change in the light-absorbing layer protects the plasmon generator from thermal expansion-induced collision, while maintaining the necessary light intensity for near-field light generation.
2Length of moving object
If the plasmon generator protrudes toward the magnetic recording medium due to thermal expansion, then the distance between them becomes shorter, but this causes unintentional collision and deformation
Solution Approach 1:
The light-absorbing layer serves as a sacrificial intermediary that undergoes thermal expansion and protrusion instead of the plasmon generator. This mediator absorbs the mechanical stress and thermal expansion, preventing the plasmon generator from colliding with and deforming the magnetic recording medium, thereby preserving structural integrity while maintaining appropriate spacing.
Solution Approach 2:
The light-absorbing layer acts as a beforehand cushioning element that is designed to protrude first in response to thermal expansion. This prior cushioning effect prevents direct contact between the plasmon generator and the magnetic recording medium, cushioning against potential collision and deformation before they can occur.
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 effectively decreases the contact probability between the plasmon generator and the magnetic recording medium, maintaining high recording performance by ensuring the light-absorbing protrusion layer absorbs heat and protrudes instead, preventing damage and maintaining near-field light generation capacity.
Implementation Method 1
a light-absorbing protrusion layer provided on a leading side of the plasmon generator
Implementation Method 2
the plasmon generator generates heat (is thermally expanded), and thus easily protrudes toward the magnetic recording medium
Implementation Method 3
a waveguide allowing the laser light to propagate therethrough
Implementation Method 4
surface plasmon polariton coupling is used in order to prevent overheat of the plasmon generator due to direct irradiation of light. In this case, the light propagating through the waveguide (guided light) is not directly applied to the plasmon generator, and the guided light is coupled to the plasmon generator through evanescent coupling. As a result, surface plasmon polaritons are generated on a surface of the plasmon generator.
Data Source
AI summary
A thermally-assisted magnetic recording head of the invention includes: a waveguide; a plasmon generator; and a light-absorbing protrusion layer provided on a leading side of the plasmon generator. A ratio W1/W2 is within a range from 2/3 to 55/3, where W1 is a width of the light-absorbing protrusion layer in an air-bearing surface, and W2 is a width of the waveguide in the air-bearing surface.