Multilayer Tapered Waveguide for Heat-Assisted Magnetic Recording
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Solution Overview
Problem
In thermally assisted magnetic/optical recording, existing technologies face challenges in efficiently focusing electromagnetic waves to achieve precise data bit dimensions and effective heat dissipation for recording, particularly due to the sensitivity of local surface plasmons to the shape and location of near-field transducers and the need for cooling mechanisms.
Innovation Solution
The use of a multilayer waveguide structure with a metallic layer having a higher propagation constant than adjacent dielectric layers, forming a tapered opening that confines light and enhances heat dissipation, allowing for a more focused and efficient electromagnetic wave focal region for recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a planar solid immersion mirror lens is used to focus electromagnetic waves, then the light can be focused to a focal region, but the optical spot size is large and light delivery efficiency is low
Solution Approach 1:
The patent transitions from a planar 2D focusing approach to a 3D tapered waveguide structure. The tapered opening confines light in multiple dimensions (transverse and longitudinal), compressing the optical spot size significantly while improving light delivery efficiency to the focal region adjacent to the storage medium.
Solution Approach 2:
The tapered waveguide structure creates a localized region with enhanced electromagnetic field confinement. The varying cross-section of the tapered opening provides different confinement properties at different positions, with the narrowest region adjacent to the storage medium achieving maximum field concentration and minimum spot size.
2Illumination intensity
If a near-field optical transducer is placed near the PSIM focus, then local surface plasmons can be formed, but the transducer requires cooling mechanisms due to heat generation from light absorption
Solution Approach 1:
The patent extracts the near-field transducer component entirely, replacing it with a tapered waveguide structure that directly confines and focuses light. This eliminates the metal nano-structure that absorbs light and generates heat, removing the need for cooling mechanisms while maintaining the ability to form localized surface plasmons in the storage medium.
Solution Approach 2:
The tapered waveguide acts as an intermediary structure between the light source and the storage medium. Instead of using a metal transducer that absorbs light, the dielectric waveguide confines and guides the electromagnetic field, allowing light to be delivered efficiently to the focal region without excessive heat generation in the transducer itself.
3Reliability
If the near-field transducer is buried in a dielectric of low thermal dissipation, then the transducer structure is protected, but heat dissipation becomes inefficient
Solution Approach 1:
The patent removes the buried near-field transducer structure entirely, replacing it with a tapered waveguide that does not require burial in low thermal dissipation dielectric. This eliminates the heat dissipation problem associated with trapping hot components in thermally insulating materials.
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 compresses the optical spot size by a significant factor, increasing light delivery efficiency and absorption in the magnetic recording layer, while effectively dissipating heat, thereby improving the recording process.
Implementation Method 1
a first waveguide configured to focus an electromagnetic wave to a focal region
Implementation Method 2
a second waveguide defining an opening having an end positioned adjacent to the focal region, the second waveguide including a first metallic layer
Data Source
AI summary
An apparatus includes a first waveguide configured to focus an electromagnetic wave to a focal region, and a second waveguide defining an opening having an end positioned adjacent to the focal region, the second waveguide including a first metallic layer, and second and third layers positioned on opposite sides of the first metallic layer, wherein the first metallic layer has a first propagation constant larger than propagation constants of the second and third layers.