Thermally-Assisted Magnetic Recording Head Plasmon Generator Protrusion Control
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Solution Overview
Problem
Thermally-assisted magnetic recording heads face challenges with plasmon generators experiencing excessive temperature increases, leading to volumetric expansion and protrusion, which disrupts the magnetic recording process by altering the servo signal readability during write operations.
Innovation Solution
A method of manufacturing a thermally-assisted magnetic recording head that includes a waveguide and a plasmon generator, where the plasmon generator is configured to have a surface plasmon excited through evanescent light generated from the waveguide, and the surface is polished to prevent protrusion by controlling the temperature expansion, ensuring the plasmon generator remains within the medium-facing surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the plasmon generator is directly irradiated with light to generate near-field light, then near-field light generation is achieved, but the plasmon generator experiences excessive temperature increase and volumetric expansion causing protrusion
Solution Approach 1:
The patent introduces an intermediary mechanism where the plasmon generator is not directly irradiated with light but instead generates near-field light through evanescent light from the waveguide. This intermediary approach (using evanescent light as a mediator) reduces direct thermal loading on the plasmon generator while still achieving the desired near-field light generation effect.
Solution Approach 2:
The patent replaces the direct optical irradiation mechanism with an evanescent light-based mechanism. Instead of using a conventional direct light source that causes heating, the system uses the evanescent field from the waveguide to excite surface plasmons, substituting a thermal-mechanical process with a field-based optical process that generates less heat.
2Reliability
If the plasmon generator volume is increased to reduce temperature increase, then thermal stability is improved, but the plasmon generator protrudes from the medium facing surface due to volumetric expansion
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for the volumetric expansion of the plasmon generator. During the polishing process, the system anticipates the future thermal expansion and adjusts the plasmon generator's initial position or the polishing depth accordingly, so that after thermal expansion occurs during operation, the plasmon generator remains flush with the medium facing surface rather than protruding.
Solution Approach 2:
The patent changes the physical parameters of the polishing process by introducing light into the core of the waveguide during polishing. This causes the plasmon generator to expand thermally during the polishing operation itself, allowing the polishing to be performed at the expanded state. This parameter change ensures that when the plasmon generator returns to its normal temperature during operation, it maintains the correct position without protrusion.
3Manufacturing precision
If light is introduced into the waveguide core during polishing to expand the plasmon generator, then protrusion is suppressed, but the polishing process becomes more complex
Solution Approach 1:
The patent merges two separate processes (light introduction and polishing) into a single integrated operation. By introducing light into the waveguide core during the polishing process, the system combines the thermal expansion effect with the material removal process, achieving both position compensation and surface finishing in one step rather than requiring separate operations.
Solution Approach 2:
The patent applies self-service by using the plasmon generator's own thermal response to light as the polishing mechanism. The plasmon generator naturally expands when exposed to light, and this self-generated expansion is utilized to achieve the correct positioning. The system uses the material's inherent thermal properties rather than requiring external mechanical adjustment mechanisms.
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 approach effectively suppresses the volumetric expansion of the plasmon generator due to temperature increases, preventing it from protruding and maintaining the integrity of the magnetic recording process by ensuring consistent servo signal readability.
Implementation Method 1
the core has an evanescent light generating surface that generates evanescent light based on the light propagating through the core
Implementation Method 2
the plasmon generator has an outer surface that includes a plasmon exciting part... Surface plasmons are excited on the plasmon exciting part through coupling with the evanescent light generated from the evanescent light generating surface
Implementation Method 3
The energy of the light applied to the plasmon generator is mostly reflected off the surface of the plasmon generator, or transformed into thermal energy and absorbed by the plasmon generator
Implementation Method 4
The plasmon generator is small in volume since the size of the plasmon generator is set to be smaller than or equal to the wavelength of the light. The plasmon generator therefore shows a significant increase in temperature when it absorbs the thermal energy. As a result, there arises the problem that the plasmon generator melts.
Data Source
AI summary
A method of manufacturing a thermally-assisted magnetic recording head includes the steps of: forming a preliminary head section that has a surface to be polished and includes a magnetic pole, a waveguide, and a preliminary plasmon generator; causing a volumetric expansion of the preliminary plasmon generator with heat by introducing light into the core of the waveguide of the preliminary head section; and polishing the surface to be polished of the preliminary head section into a medium facing surface. The preliminary plasmon generator has an end face located in the surface to be polished. In the step of polishing the surface to be polished, the surface to be polished is subjected to polishing with the preliminary plasmon generator expanded in volume, whereby the end face of the preliminary plasmon generator is polished into the front end face, and the preliminary plasmon generator thereby becomes the plasmon generator.