Thermally Assisted Magnetic Head With Integrated Laser and Diffraction Grating
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Solution Overview
Problem
Existing thermally assisted magnetic heads face challenges in achieving high mass productivity and high recording densities due to limitations in integrating light sources and efficient heating mechanisms, leading to reduced thermal stability and increased coercivity in magnetic microparticles.
Innovation Solution
A thermally assisted magnetic head with a surface-emitting semiconductor laser and a diffraction grating is integrated onto a slider substrate, allowing for collective positioning and efficient optical coupling of emission light to an optical waveguide core, which heats the magnetic recording medium, thereby improving recording density and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic microparticles are made smaller to enhance recording density, then recording density is improved, but magnetization thermal stability deteriorates
Solution Approach 1:
The patent changes the physical state of the recording medium by heating it temporarily during the writing process. This parameter change (temperature) allows smaller magnetic particles to be written to by reducing their coercivity during heating, then restoring thermal stability when cooled, thus resolving the contradiction between recording density and thermal stability
Solution Approach 2:
The patent employs periodic heating and cooling cycles of the recording medium. The medium is heated briefly during writing to reduce coercivity, then cooled to restore thermal stability. This periodic action allows small particles to be written while maintaining long-term thermal stability
2Stability of the object's composition
If coercivity is increased to improve thermal stability, then magnetization thermal stability is improved, but writing capability deteriorates
Solution Approach 1:
The patent temporarily changes the temperature parameter of the recording medium during writing to reduce coercivity, enabling successful writing. After writing, the medium returns to ambient temperature and restores high coercivity for thermal stability, thus resolving the contradiction between writing capability and thermal stability
3Stability of the object's composition
If a light source is provided at a position spaced apart from the magnetic head, then thermal stability is maintained, but mass productivity deteriorates
Solution Approach 1:
The patent merges the light source with the magnetic head into an integrated assembly. The laser diode is mounted on the same slider substrate as the magnetic head, allowing simultaneous positioning and collective fixation. This merging improves mass productivity while thermal isolation structures maintain thermal stability
4Use of energy by moving object
If emission light directly irradiates the magnetic recording medium, then heating efficiency is improved, but positioning precision deteriorates
Solution Approach 1:
The patent introduces an optical waveguide core as an intermediary between the laser diode and the magnetic recording medium. The waveguide receives light from the laser and guides it precisely to the intended location on the medium, achieving both efficient heating and accurate positioning. The diffraction grating further refines the light direction for precise spot formation
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 enhances mass productivity and enables the magnetic head to cope with higher recording densities by reducing the time between heating and magnetic field application, while maintaining thermal stability and coercivity within acceptable limits.
Implementation Method 1
a diffraction grating, which is provided in the optical waveguide core or further towards the second surface than the optical waveguide core, and the refractive index of which varies periodically along a direction in which the optical waveguide core extends, and wherein the surface-emitting semiconductor laser is provided opposing the second surface so that emission light from the surface-emitting semiconductor laser is incident onto the diffraction grating, and the diffraction grating causes at least part of emission light from the surface-emitting semiconductor laser to be optically coupled to the optical waveguide core
Implementation Method 2
heats the magnetic recording medium, thereby improving recording density and productivity
Implementation Method 3
an optical waveguide core extending along the first surface and having a light exit surface at the medium-facing surface
Implementation Method 4
a main magnetic pole that generates a write magnetic field from an end face on the side of the medium-facing surface
Data Source
AI summary
A thermally assisted magnetic head includes: a slider having a medium-facing surface; and a surface-emitting semiconductor laser. The slider has: a slider substrate, on which part of the medium-facing surface is formed; and a magnetic head portion, on which another part of the medium-facing surface is formed, and which has a first surface in contact with a head stacking surface of the slider substrate and a second surface opposite the first surface. The magnetic head portion has: a main magnetic pole that generates a write magnetic field from an end face on the side of the medium-facing surface; an optical waveguide core extending along the first surface and having a light exit surface at the medium-facing surface; and a diffraction grating, which is provided in the optical waveguide core or further towards the second surface than the optical waveguide core, and the refractive index of which varies periodically along the direction in which the optical waveguide core extends. The surface-emitting semiconductor laser is provided opposing the second surface so that emission light from the surface-emitting semiconductor laser is incident onto the diffraction grating, and the diffraction grating causes at least part of emission light from the surface-emitting semiconductor laser to be optically coupled to the optical waveguide core.