Near-Field Light Generator Waveguide Plasmon Structure
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Solution Overview
Problem
Conventional thermally-assisted magnetic recording heads face challenges in efficiently generating near-field light due to poor use efficiency of laser light and temperature-related issues with plasmon antennas, which affect recording density and thermal stability of magnetic media.
Innovation Solution
A near-field light generator is designed with a waveguide and plasmon generator arrangement where the outer surface of the waveguide and the edge part of the plasmon generator face each other, using a clad layer and dielectric film to control the distance and reduce variations, and a manufacturing method involving reactive ion etching and atomic layer deposition to form a triangular-prism-shaped plasmon generator with inclined surfaces and a near-field light generating part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If laser light is directly applied to plasmon antenna, then near-field light is generated, but use efficiency of laser light is poor due to reflection and thermal energy absorption
Solution Approach 1:
The patent introduces a waveguide as an intermediary component between the laser light source and the plasmon generator. The waveguide transmits laser light to the plasmon generator with minimal loss, avoiding direct illumination of the plasmon antenna. This mediator structure reduces both reflection losses and unwanted thermal energy absorption, thereby improving overall laser light use efficiency while maintaining reliable near-field light generation.
2Temperature
If plasmon antenna absorbs thermal energy, then temperature rises, but plasmon antenna expands and protrudes to damage recording medium
Solution Approach 1:
The patent separates the plasmon generator into distinct functional regions: a heated region that absorbs thermal energy for near-field light generation, and a non-heated region that remains at lower temperature. This segmentation is achieved through the waveguide structure that directs and confines thermal energy to specific areas, preventing uniform heating and expansion of the entire plasmon antenna. The non-heated region maintains structural integrity and prevents protrusion that would damage the recording medium.
Solution Approach 2:
The patent applies local quality by creating spatial variation in thermal properties and geometry of the plasmon generator. Different regions of the plasmon generator have different thermal characteristics - the active region near the waveguide experiences controlled heating for near-field light generation, while other regions maintain lower temperatures. This localized thermal management allows effective heating where needed while preventing harmful expansion and protrusion in other areas.
3Reliability
If distance between waveguide and plasmon generator is not controlled, then near-field light generation efficiency varies, but manufacturing precision is difficult to achieve
Solution Approach 1:
The patent merges the waveguide and plasmon generator into an integrated structure where the plasmon generator is formed in direct association with the waveguide. This integration ensures a fixed, predetermined distance between the two components, eliminating variability in spacing. The merged structure maintains reliable near-field light generation efficiency while simplifying manufacturing, as the fixed geometric relationship is built into the single integrated component rather than requiring precise assembly of separate parts.
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 the efficiency of near-field light generation, reduces variations in distance, and minimizes the spot diameter, thereby improving recording density and thermal stability while preventing plasmon generator protrusion and temperature rise.
Implementation Method 1
exciting surface plasmons on the plasmon generator by utilizing evanescent light that results from total reflection of the light propagated through the waveguide at the outer surface of the waveguide
Implementation Method 2
The laser light applied to the plasmon antenna excites surface plasmons on the plasmon antenna, and near-field light is generated based on the surface plasmons
Data Source
AI summary
A near-field light generator includes: a waveguide; a clad layer having a penetrating opening and disposed on the waveguide; a plasmon generator accommodated in the opening; and a dielectric film interposed between the plasmon generator and each of the waveguide and the clad layer. In a method of manufacturing the near-field light generator, an initial clad layer is initially formed on the waveguide, and then the initial clad layer is taper-etched by RIE to form a recess that does not reach the top surface of the waveguide. Subsequently, the recess is etched by wet etching until the top surface of the waveguide is exposed in part. Next, the dielectric film is formed in the opening, and the plasmon generator is formed on the dielectric film.