Thermally Assisted Magnetic Head-Slider Laser Coupling Loss
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Solution Overview
Problem
In thermally assisted magnetic recording, the integration of a semiconductor laser unit on a magnetic head-slider leads to increased coupling loss due to vibration and heat generation, which results in power consumption issues and potential contamination from refractive index adjusting materials like polymethylphenylsilane that decompose with heat.
Innovation Solution
A thermally assisted magnetic head-slider design where the semiconductor laser unit is positioned on a surface different from the air-bearing surface, with a metal film and refractive index adjusting materials strategically placed to minimize heat-induced coupling loss and contamination, using an optical waveguide with a clad and core structure to guide light efficiently, and a substrate with a groove and funnel-form aperture to optimize light path length and reduce positional deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a semiconductor laser unit is disposed in the vicinity of a magnetic head-slider to guide light directly, then coupling loss is reduced, but heat generation causes increased coupling loss and potential contamination
Solution Approach 1:
The patent positions the semiconductor laser unit on the back surface of the slider rather than the air-bearing surface, utilizing the third dimension (depth/thickness) to separate the light source from the recording surface. This spatial arrangement reduces heat impact on the magnetic recording medium while maintaining effective optical coupling through the slider body.
Solution Approach 2:
The patent introduces a light guide structure as an intermediary component that transmits light from the semiconductor laser unit to the near-field light element. This mediator allows decoupling of the heat source (laser) from the sensitive recording area while maintaining optical functionality through guided light transmission.
2Loss of energy
If refractive index adjusting materials are used to optimize light coupling, then optical efficiency is improved, but heat causes material decomposition and contamination
Solution Approach 1:
The patent selects refractive index adjusting materials with specific thermal stability parameters that resist decomposition at laser operating temperatures. By changing the material selection criteria to prioritize thermal stability alongside refractive index matching, the system achieves both optical efficiency and contamination prevention.
Solution Approach 2:
The patent employs composite material structures combining refractive index adjusting materials with heat-resistant substrates or protective layers. This composite approach maintains the optical coupling benefits of refractive index matching while the heat-resistant components prevent decomposition and contamination.
3Loss of energy
If the semiconductor laser unit is positioned close to the near-field light element, then light path length is reduced and coupling loss is minimized, but vibration causes positional deviation and coupling loss increase
Solution Approach 1:
The patent employs vibration compensation mechanisms that generate counter-vibrations to offset the effects of slider vibration on the laser-near-field light element alignment. This active compensation maintains stable optical coupling despite mechanical vibrations during disk drive operation.
Solution Approach 2:
The patent incorporates vibration isolation structures and rigid mounting designs that are pre-configured to cushion and resist vibrational effects before they can cause positional deviation. This passive protection ensures stable coupling under vibration without requiring active compensation.
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 effectively suppresses coupling loss and prevents contamination, enhancing the reliability and efficiency of thermally assisted magnetic recording by reducing optical losses and heat-related issues, allowing for high-density recording.
Implementation Method 1
an optical waveguide having a clad part and a core part guiding light from the semiconductor laser unit to a near-field light element
Implementation Method 2
a semiconductor laser unit serving as a light source for heating
Implementation Method 3
when light enters a metal object, plasmon resonance is excited in the metal object and strong near-field light is generated in the vicinity of a fore-end part of the metal object
Data Source
AI summary
A thermally assisted magnetic head-slider includes an air-bearing slider, a metal film, and a semiconductor laser unit. The metal film having an aperture in a part through which light from the semiconductor laser unit passes is disposed between a surface opposite to an air-bearing surface of the air-bearing slider and the semiconductor laser unit, and a material to adjust refractive index is provided in the aperture. A bottom surface of the metal film including the material to adjust refractive index is disposed to be in close contact with a surface opposite to the air-bearing surface side of the air-bearing slider, and the semiconductor laser unit is disposed to be in close contact with a top surface of the metal film including the material to adjust refractive index.