Thermally-Assisted Magnetic Recording Head Plasmon Generator Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In thermally-assisted magnetic recording, the proximity of the plasmon generator and magnetic pole is critical for achieving high recording density, but the absorption of surface plasmons into the magnetic pole reduces light use efficiency, conflicting with the need for close proximity and high magnetic field gradients.
Innovation Solution
A thermally-assisted magnetic recording head is designed with a plasmon generator that includes a light penetration suppressing part with a higher extinction coefficient than the plasmon propagating part, allowing the magnetic pole to be in surface-contact with this part, thereby reducing absorption and maintaining close proximity to the NF-light generating point, while using a light penetration suppressing part made of materials like aluminum or indium to prevent significant reduction in light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the plasmon generator is placed close to the magnetic pole to achieve high recording density, then the magnetic field gradient is improved, but the light use efficiency deteriorates due to absorption of surface plasmons into the magnetic pole
Solution Approach 1:
The plasmon generator is divided into two distinct parts: a plasmon propagating part (made of gold or silver) that generates and transmits surface plasmons, and a light penetration suppressing part (made of aluminum or indium) that prevents plasmon absorption by the magnetic pole. This segmentation allows each part to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The light penetration suppressing part acts as an intermediary layer between the plasmon propagating part and the magnetic pole. It mediates the interaction by blocking the harmful absorption of surface plasmons by the magnetic pole while allowing the plasmon propagating part to maintain close proximity to the magnetic pole for high recording density.
2Force
If the plasmon generator is placed close to the magnetic pole, then the gradient of write field is improved, but the absorption of surface plasmons into the magnetic pole increases
Solution Approach 1:
The plasmon generator is segmented into a plasmon propagating part that generates surface plasmons and a light penetration suppressing part that prevents their absorption by the magnetic pole. This allows the generator to maintain close proximity to the magnetic pole for high field gradient while the suppressing part blocks the harmful absorption.
Solution Approach 2:
The light penetration suppressing part converts the potentially harmful absorption of surface plasmons by the magnetic pole into a beneficial effect by using its high extinction coefficient to reflect or absorb the plasmons that would otherwise be lost, thereby improving overall system 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 configuration enables high light density near-field light application to the magnetic recording medium, achieving higher recording densities by minimizing absorption and maintaining efficient light use while keeping the write field and NF-light generating points close, thus enhancing thermally-assisted magnetic recording performance.
Implementation Method 1
a waveguide for transmitting laser light; the laser light is coupled with the plasmon generator in a surface plasmon mode
Implementation Method 2
the laser light is coupled with the plasmon generator in a surface plasmon mode and the excited surface plasmon is propagated to a surface opposed to the medium surface, thereby near-field light is provided
Implementation Method 3
a plasmon generator that converts light received from a waveguide into NF-light
Implementation Method 4
a light penetration suppressing part formed of a material having an extinction coefficient greater than an extinction coefficient of a material that forms the plasmon propagating part
Implementation Method 5
a magnetic recording medium is irradiated with near-field light (NF-light), thereby anisotropic magnetic field of the medium is lowered
Implementation Method 6
thermally-assisted magnetic recording technology that enables the use of magnetic recording media having higher thermal stability of magnetization
Data Source
AI summary
Provided is a thermally-assisted magnetic recording head in which NF-light with sufficiently high light density can be applied to a medium while a write-field generating point and a near-field light (NF-light) generating point are close to each other. The head comprises a plasmon generator provided between a magnetic pole and a waveguide and configured to be coupled with light propagating through the waveguide in a surface plasmon mode to emit NF-light. The plasmon generator comprises: a plasmon propagating part comprising a propagation edge for propagating surface plasmon excited by the light; and a light penetration suppressing part with an extinction coefficient greater than the plasmon propagating part. The light penetration suppressing part is in surface-contact with a surface portion of the plasmon propagating part excluding the propagation edge, and the magnetic pole is in surface-contact with the light penetration suppressing part. This configuration can avoid significant reduction in light use efficiency of an optical system generating NF-light due to partial absorption of electromagnetic field (light) into the magnetic pole.