Near-field Light Generator Plasmon Structure Reliability
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Solution Overview
Problem
Existing near-field light generators for thermally-assisted magnetic recording heads, particularly those using plasmon generators made of Au or Ag, face issues with reliability due to thermal expansion, deformation, and reduced heating performance, leading to potential damage and degradation of the recording medium and plasmon generator.
Innovation Solution
A near-field light generator design featuring a waveguide with a core and a plasmon generator having a first and second portion, where the second portion includes a second front end face with a smaller area, and an intermediate layer of higher Vickers hardness between metal layers, enhancing reliability and preventing deformation, while maintaining efficient surface plasmon excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an entire plasmon generator is formed of Au or Ag, then near-field light generation efficiency is improved, but the plasmon generator becomes soft and susceptible to deformation during polishing and etching
Solution Approach 1:
The plasmon generator is constructed as a composite structure with a hard substrate layer (e.g., Cr, Ti, W) providing mechanical strength and a soft metal layer (Au or Ag) on top providing plasmon generation capability. This composite structure resolves the contradiction by combining materials with complementary properties - the hard substrate prevents deformation during manufacturing while the soft metal layer maintains near-field light generation efficiency.
2Use of energy by moving object
If the plasmon generator is made of soft metal materials, then near-field light generation is improved, but the front end face becomes significantly recessed during polishing and etching
Solution Approach 1:
The hard substrate layer provides resistance to polishing and etching, maintaining the front end face position accuracy while the soft metal layer on top enables efficient near-field light generation. The substrate acts as a protective foundation that prevents the soft metal layer from being excessively removed during manufacturing processes.
3Use of energy by moving object
If the plasmon generator is made of Au or Ag with high thermal expansion coefficient, then near-field light generation is improved, but the plasmon generator expands and protrudes toward the recording medium when temperature rises
Solution Approach 1:
The hard substrate layer typically has a lower thermal expansion coefficient than the soft metal layer. This creates a differential expansion structure where the substrate constrains the thermal expansion of the metal layer, reducing the overall dimensional instability and preventing excessive protrusion toward the recording medium when temperature rises.
Solution Approach 2:
The invention utilizes the thermal expansion properties of different materials in the composite structure. By selecting a substrate material with appropriate thermal expansion characteristics, the design compensates for the high thermal expansion of the Au or Ag layer, maintaining dimensional stability during thermal cycles.
4Use of energy by moving object
If the plasmon generator is made of soft metal materials, then near-field light generation is improved, but the plasmon generator is damaged by contact with the recording medium or corroded by high temperature air
Solution Approach 1:
The hard substrate layer serves as a protective barrier that prevents the soft metal layer from direct contact with the recording medium and high temperature air. This protective structure maintains operational reliability by preventing mechanical damage and corrosion while preserving the near-field light generation capability of the metal layer.
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
The design improves the reliability and heating performance of the near-field light generator, preventing damage to the recording medium and plasmon generator, and allows for efficient surface plasmon excitation, thus enhancing the overall performance of thermally-assisted magnetic recording heads.
Implementation Method 1
The waveguide includes a core through which light propagates
Implementation Method 2
surface plasmons are excited on the surface of the plasmon generator through coupling with the evanescent light
Implementation Method 3
evanescent light is generated at the surface of the core and surface plasmons are excited on the surface of the plasmon generator through coupling with the evanescent light
Implementation Method 4
a write magnetic field and heat are simultaneously applied to the area of the recording medium where to write data, whereby the area is made to increase in temperature
Data Source
AI summary
A plasmon generator includes a first portion and a second portion. A core of a waveguide includes a main body portion and a protruding portion. The main body portion has a first surface and a second surface parallel to each other. The protruding portion lies on the first surface. A cladding of the waveguide includes a receiving-portion-forming layer lying on the first surface. At least part of the first portion of the plasmon generator is received in a receiving portion defined by the protruding portion and the receiving-portion-forming layer.