Heat-Assisted Magnetic Recording Head Plasmon Generator
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Solution Overview
Problem
Heat-assisted magnetic recording heads face inefficiencies in transforming light into near-field light due to direct irradiation of plasmon antennas, leading to temperature increases and reduced servo signal readability, and the placement of magnetic poles near light cores results in light absorption and decreased efficiency.
Innovation Solution
A heat-assisted magnetic recording head design featuring a waveguide with a core and clad, a plasmon generator with evanescent light generating surfaces, and a dielectric layer with a lower refractive index, where surface plasmons are excited and propagated through width changing portions to generate intense near-field light, positioning the magnetic pole between the core and plasmon generator to prevent light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a plasmon antenna is directly irradiated with light to generate near-field light, then near-field light generation is achieved, but the transformation efficiency is very low and the plasmon antenna temperature increases significantly
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the light source and the plasmon antenna. The dielectric layer guides light through total internal reflection to generate evanescent light, which then excites surface plasmons on the antenna without direct light irradiation, thereby improving transformation efficiency and preventing excessive temperature increase
Solution Approach 2:
The direct optical irradiation mechanism is replaced with a waveguide-based light guidance system using total internal reflection. This substitution allows indirect energy transfer to the plasmon antenna through evanescent fields, achieving more efficient energy conversion and better thermal management
2Volume of moving object
If the plasmon antenna volume is reduced to maintain near-field light generation, then the antenna size is minimized, but the temperature increase becomes more significant due to absorbed thermal energy
Solution Approach 1:
The dielectric layer acts as a mediator that decouples the light source from the small plasmon antenna. By guiding light through total internal reflection and generating evanescent fields at the dielectric-plasmon interface, the system enables efficient energy transfer to the small antenna without direct irradiation, preventing excessive temperature rise in the miniaturized structure
3Power
If the magnetic pole is placed near the light core to enable data writing, then write field generation is improved, but light absorption increases and transformation efficiency decreases
Solution Approach 1:
The dielectric layer serves as an intermediary that separates the magnetic pole from the light propagation path. By guiding light through the dielectric layer via total internal reflection, the system enables the magnetic pole to be positioned near the light core without direct light absorption, maintaining both write field generation capability and optical transformation 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
This design enhances the efficiency of light transformation into near-field light, intensifies the generated near-field light, and maintains the magnetic pole's proximity to the core without absorbing light, improving data writing capabilities and preventing thermal expansion issues.
Implementation Method 1
a waveguide including a core and a clad, the core propagating light
Implementation Method 2
the plasmon generator has an outer surface, the outer surface including a plasmon exciting surface and a plasmon propagating surface... surface plasmons are excited on the metal by utilizing evanescent light that results from the total reflection of the light propagated through the dielectric at the surface of the dielectric
Implementation Method 3
evanescent light that results from the total reflection of the light propagated through the dielectric at the surface of the dielectric
Data Source
AI summary
A plasmon generator has a near-field light generating part located in a medium facing surface. The plasmon generator has an outer surface including a plasmon exciting surface and a plasmon propagating surface that face toward opposite directions. The plasmon exciting surface is substantially in contact with an evanescent light generating surface of a waveguide's core. The plasmon propagating surface is in contact with a dielectric layer that has a refractive index lower than that of the core. The plasmon exciting surface includes a first width changing portion. The plasmon propagating surface includes a second width changing portion. Each of the first and second width changing portions has a width that decreases with decreasing distance to the medium facing surface, the width being in a direction parallel to the medium facing surface and the evanescent light generating surface.