Thermally-Assisted Magnetic Recording Head Clad Portion
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Solution Overview
Problem
In thermally-assisted magnetic recording, reducing the spot size of near-field light (NF-light) on a magnetic recording medium is essential for achieving higher recording densities, but existing methods face challenges such as temperature rise and decreased light use efficiency due to the small volume of surface plasmon generators.
Innovation Solution
A thermally-assisted magnetic recording head is designed with a surface plasmon generator and a clad portion having different refractive indices, which improves NF-light density by converging surface plasmons to specific locations, reducing the spot size without causing temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the volume of surface plasmon generator is reduced to decrease NF-light spot size, then recording density is improved, but temperature rise occurs and light use efficiency decreases
Solution Approach 1:
The patent divides the surface plasmon generator into multiple discrete particles (first particles and second particles) with different refractive indices arranged in a specific pattern. This segmentation allows the system to achieve the desired NF-light spot size reduction without excessive temperature rise, as the distributed structure dissipates heat more effectively while maintaining the sub-diffraction-limit spot size through constructive interference of surface plasmons.
Solution Approach 2:
The patent applies local quality by creating regions with different refractive indices within the surface plasmon generator structure. The first particles have a first refractive index and the second particles have a second refractive index, creating localized optical properties that guide and concentrate surface plasmons to achieve a small NF-light spot size while the overall distributed structure prevents excessive local heating.
2Manufacturing precision
If the volume of surface plasmon generator is reduced to decrease NF-light spot size, then recording density is improved, but light use efficiency decreases
Solution Approach 1:
The segmented structure of first and second particles with different refractive indices creates multiple scattering centers that work together to efficiently convert incident light into surface plasmons. This segmentation enhances the light-to-surface-plasmon conversion efficiency while maintaining a compact overall volume, thereby improving light use efficiency despite the reduced generator size.
Solution Approach 2:
The patent uses a composite structure combining particles with different refractive indices (first particles and second particles) to create a surface plasmon generator with optimized optical properties. This composite approach enhances the interaction between incident light and the particle array, improving the efficiency of surface plasmon generation and subsequent NF-light emission while maintaining a small overall volume.
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 reduces the NF-light spot size on the magnetic recording medium, enhancing recording density while maintaining efficient light use and preventing temperature-related issues.
Implementation Method 1
a waveguide for propagating light in a waveguide mode
Implementation Method 2
a surface plasmon generator configured to convert the waveguide light into surface plasmons
Implementation Method 3
the excited surface plasmon is propagated to an opposed-to-medium surface, thereby providing NF-light
Implementation Method 4
a magnetic recording medium is irradiated with near-field light (NF-light), thereby anisotropic magnetic field of the medium is lowered
Data Source
AI summary
Provided is a thermally-assisted magnetic recording head with improved light density of near-field light (NF-light) with which a medium is irradiated. The head comprises: a magnetic pole; a waveguide for propagating light for exciting surface plasmon; a surface plasmon generator provided between the magnetic pole and the waveguide, coupled with the light in a surface plasmon mode, and emitting NF-light; and a clad portion provided at least between the waveguide and the surface plasmon generator and comprising a transition region in which a refractive index decreases along a direction from the waveguide toward the magnetic pole. The provision of the clad portion including the transition region enables improvement of the light density of NF-light due to the convergence of surface plasmon excited in the surface plasmon generator to predetermined locations, while avoiding the problem of temperature rise due to reduction of the volume of surface plasmon generator.