Surface Plasmon Antenna for Thermal-Assisted Magnetic Recording
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Solution Overview
Problem
Conventional plasmon antennas used in thermal-assisted magnetic recording face challenges due to high temperature rise, leading to reduced light use efficiency and difficulty in maintaining the proximity of the read head to the magnetic recording medium, which affects data reading and writing accuracy.
Innovation Solution
A surface plasmon antenna design where laser light is coupled in a surface plasmon mode through a waveguide, avoiding direct absorption and allowing for controlled near-field light generation with improved thermal management, enabling closer proximity to the magnetic pole and enhanced write field gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light is directly applied to a plasmon antenna to generate near-field light, then near-field light is generated for thermal-assisted magnetic recording, but the plasmon antenna temperature rises excessively to 500°C, causing thermal expansion and protrusion toward the magnetic recording medium
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the laser light source and the plasmon antenna. This dielectric layer has optimized thickness and refractive index to enable efficient light coupling to the plasmon antenna while absorbing excess thermal energy, preventing the antenna from overheating and protruding toward the magnetic recording medium.
Solution Approach 2:
The patent optimizes the thickness and refractive index parameters of the dielectric layer to achieve the desired balance between light coupling efficiency and thermal management. By changing these physical parameters, the system achieves effective near-field light generation while maintaining plasmon antenna temperature within acceptable limits.
2Manufacturing precision
If the plasmon antenna is made smaller to improve recording density, then the recording density increases, but the light use efficiency decreases and thermal energy concentration increases
Solution Approach 1:
The patent employs a composite structure consisting of the plasmon antenna made from metal material and a dielectric material layer. This composite configuration allows the small-sized plasmon antenna to maintain high recording density while the dielectric component improves light coupling efficiency and manages thermal energy distribution, preventing excessive heat concentration.
3Temperature
If the plasmon antenna protrudes toward the magnetic recording medium due to thermal expansion, then the read head distance increases, but data reading accuracy deteriorates
Solution Approach 1:
The dielectric layer serves as a thermal cushioning layer that absorbs and distributes thermal energy before it can cause excessive expansion of the plasmon antenna. This beforehand cushioning prevents the antenna from protruding toward the magnetic recording medium, maintaining the optimal read head distance and ensuring data reading accuracy.
4Stability of the object's composition
If the anisotropic magnetic field of the magnetic recording medium is increased to improve thermal stability, then the thermal stability improves, but the write field intensity required exceeds the head's write field limit
Solution Approach 1:
The patent replaces the conventional electromagnetic write field system with a thermal-assisted system. Instead of relying solely on high write field intensity from the electromagnetic transducer, the system uses near-field light generated by the plasmon antenna to locally heat the magnetic recording medium, temporarily reducing its anisotropic magnetic field and enabling data writing at field intensities within the head's capabilities.
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 improves light use efficiency, reduces excessive temperature rise, and ensures stable thermal-assisted magnetic recording with increased recording density, achieving better data writing and reading accuracy.
Implementation Method 1
laser light is coupled in a surface plasmon mode through a waveguide
Implementation Method 2
generating near-field light from plasmon that is excited by irradiated laser light
Implementation Method 3
a magnetic recording medium is irradiated with near-field light, thereby anisotropic magnetic field of the medium is lowered
Data Source
AI summary
Provided is a surface plasmon antenna that can be set so that the emitting position on the end surface of the plasmon antenna where near-field light is emitted is located sufficiently close to the end of a magnetic pole. The surface plasmon antenna comprises an edge having a portion for coupling with a light in a surface plasmon mode. The edge is provided for propagating surface plasmon excited by the light and extends from the portion to a near-field light generating end surface that emits near-field light. The edge for propagating surface plasmon is a very narrow propagation region. Therefore, the near-field light generating end surface, which appears as a polished surface processed through polishing in the manufacturing of the plasmon antenna, can be made a shape with a very small size, and further can be set so that surface plasmon propagates to reach the end surface reliably.