Thermally-Assisted Magnetic Recording Head Plasmon Generator
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Solution Overview
Problem
Thermally-assisted magnetic recording heads face challenges in efficiently generating near-field light with a small spot diameter and maintaining the position of the write magnetic field close to the near-field light, due to the inefficiency of plasmon antennas in transforming light into near-field light and the temperature increase causing mechanical issues.
Innovation Solution
A thermally-assisted magnetic recording head design featuring a plasmon generator with a V-shaped portion and a flat surface part, where surface plasmons are excited through evanescent light, allowing for efficient transformation of light into near-field light with a small spot diameter, and the magnetic pole is positioned close to the plasmon generator to maintain optimal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plasmon antenna is used to generate near-field light by direct irradiation with light, then near-field light can be generated, but the transformation efficiency of light into near-field light is very low and the plasmon antenna temperature increases significantly
Solution Approach 1:
The patent introduces an evanescent light generating surface as an intermediary between the light source and the plasmon generator. This intermediary converts direct light irradiation into evanescent light, which then couples with the plasmon generator to produce near-field light. This two-step process significantly improves transformation efficiency and reduces energy loss compared to direct irradiation.
Solution Approach 2:
The patent replaces the direct optical irradiation mechanism with an evanescent light coupling mechanism. Instead of directly shining light onto the plasmon antenna, the system uses total internal reflection to generate evanescent light that couples with the plasmon generator, substituting a more efficient physical mechanism for the less efficient direct irradiation approach.
2Volume of moving object
If the plasmon antenna volume is made small to achieve sub-wavelength operation, then the near-field light spot size is reduced, but the temperature increase becomes more significant due to limited heat dissipation
Solution Approach 1:
The evanescent light generating surface acts as a mediator that decouples the light source from the plasmon generator. This allows the plasmon generator to be positioned very close to the medium facing surface (small volume) while the light source remains at a distance, enabling efficient energy transfer without direct heating of the small-volume plasmon generator.
3Illumination intensity
If the plasmon generator is positioned closer to the medium facing surface to reduce spot size, then near-field light generation efficiency is improved, but the read head end moves farther from the magnetic recording medium causing servo signal reading failure
Solution Approach 1:
The patent segments the light generation function from the read/write function. The evanescent light generating surface is positioned close to the medium facing surface for efficient near-field light generation, while the read head end remains at its proper distance from the magnetic recording medium for reliable servo signal reading. This functional segmentation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The evanescent light generating surface serves as an intermediary structure that enables the plasmon generator to be positioned optimally for near-field light generation without compromising read head positioning. This intermediary allows independent optimization of the light generation subsystem from the read subsystem.
4Productivity
If magnetic fine particles are made smaller to reduce asperities and improve recording density, then recording density is improved, but thermal stability of magnetization decreases
Solution Approach 1:
The patent changes the thermal parameter of the magnetic recording medium by using thermally-assisted magnetic recording. A heating element raises the temperature of the magnetic fine particles during writing, temporarily reducing their thermal stability and coercivity to enable data writing. After writing, the temperature returns to normal, restoring the high thermal stability of the small-volume magnetic fine particles.
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 design enhances the efficiency of near-field light generation with a small spot diameter and prevents thermal expansion issues, ensuring effective data writing and reading operations.
Implementation Method 1
The core has an evanescent light generating surface that generates evanescent light based on the light propagated through the core
Implementation Method 2
A surface plasmon is excited on the plasmon exciting part through coupling with the evanescent light generated from the evanescent light generating surface
Implementation Method 3
The near-field light generating part generates near-field light based on the surface plasmon excited on the plasmon exciting part
Implementation Method 4
a magnetic pole that has an end face located in the medium facing surface and produces a write magnetic field for writing data on the magnetic recording medium
Data Source
AI summary
A plasmon generator has an outer surface including a plasmon exciting part that faces an evanescent light generating surface of a waveguide. The outer surface further includes first and second inclined surfaces that increase in distance from each other with increasing distance from the plasmon exciting part, and a front end face. The front end face has first and second portions that are connected to each other into a V-shape. The first portion includes a first side lying at an end of the first inclined surface. The second portion includes a second side lying at an end of the second inclined surface. An angle formed between a lower part of the first side and a lower part of the second side is smaller than that formed between an upper part of the first side and an upper part of the second side.