Reduced Plasmon Shield-Generator Gap Structure for TAMR Write Heads
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Solution Overview
Problem
Current TAMR technologies face challenges in achieving both good optical efficiency and a small optical spot size due to the limitations of the gap distances between the edge plasmon generator and the optical waveguide, and the plasmon shield, which result in reduced coupling efficiency when the gaps are scaled down.
Innovation Solution
The proposed solution involves forming a triangular indentation in the optical waveguide to increase the waveguide to edge plasmon generator gap while reducing the plasmon shield to edge plasmon generator gap, either by extending the plasmon shield above the indentation or using a 'dummy' dielectric layer to block plasmon radiation, allowing for a larger waveguide to plasmon generator gap and a smaller plasmon shield to plasmon generator gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the gap between the edge plasmon generator and the plasmon shield is reduced to achieve a smaller optical spot size, then the optical spot size is reduced, but the optical coupling efficiency between the waveguide and edge plasmon generator deteriorates
Solution Approach 1:
The patent introduces a plasmon shield as a separate component positioned between the edge plasmon generator and the optical waveguide. This segmentation allows independent optimization of two gap distances: the first gap between the waveguide and edge plasmon generator (maintained larger for coupling efficiency) and the second gap between the edge plasmon generator and plasmon shield (reduced for smaller optical spot). The plasmon shield acts as an intermediary element that confines the plasmon mode without requiring the edge plasmon generator to be closer to the waveguide.
Solution Approach 2:
The plasmon shield serves as an intermediary element in the optical path. By placing the plasmon shield at a controlled distance from the edge plasmon generator, it modifies the plasmon mode distribution and confinement. This intermediary structure enables the system to achieve a smaller optical spot size while maintaining adequate optical coupling efficiency, as the plasmon shield helps concentrate the optical energy without requiring reduction of the waveguide-to-generator gap.
2Loss of energy
If the waveguide to edge plasmon generator gap is reduced to improve optical coupling, then optical coupling efficiency is improved, but the optical spot size increases
Solution Approach 1:
The patent divides the gap structure into two distinct segments: the first gap between the optical waveguide and edge plasmon generator (optimized for coupling efficiency), and the second gap between the edge plasmon generator and plasmon shield (optimized for spot size). This segmentation allows each gap to be independently optimized for its specific function without compromising the other.
Solution Approach 2:
The plasmon shield acts as an intermediary that enables the system to achieve both good optical coupling and small optical spot size. By positioning the plasmon shield at an appropriate distance from the edge plasmon generator, it confines the plasmon mode and reduces the optical spot size while allowing the waveguide-to-generator gap to remain large enough for efficient optical coupling.
3Area of moving object
If the plasmon shield is placed closer to the edge plasmon generator to reduce the optical spot, then the optical spot size is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent segments the overall gap structure into two independent gap regions with different optimization criteria. The first gap (waveguide to edge plasmon generator) is optimized for optical coupling efficiency and can be manufactured with standard precision tolerances. The second gap (edge plasmon generator to plasmon shield) is optimized for optical spot size and can be manufactured with appropriate tolerances for its specific function. This segmentation allows each gap to be manufactured independently with suitable precision requirements.
Solution Approach 2:
The plasmon shield serves as an intermediary component that helps define the optical spot size through its positioning relative to the edge plasmon generator. By using the plasmon shield as a reference element, the system achieves better control over the optical spot size while maintaining manufacturability. The plasmon shield's position can be controlled during fabrication to achieve the desired optical characteristics without requiring extremely tight tolerances on all dimensions.
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 enables a smaller optical spot size, higher thermal gradient, and improved areal density with minimal loss in optical efficiency, suitable for mass production.
Implementation Method 1
The optical energy in WG 11 is efficiently transformed to edge plasmon mode through evanescent coupling
Implementation Method 2
After being converted to plasmon mode the optical energy then concentrated at the location where heating of the medium is required
Implementation Method 3
the spot size is mainly determined by PSG which is gap distance 13 between edge plasmon generator 15 and plasmon shield 12
Data Source
AI summary
Three structures, and processes for manufacturing them, that improve the performance of a TAMR feature in a magnetic write head are disclosed. This improvement is achieved by making the separation between the edge plasmon generator and the plasmon shield less than the separation between the edge plasmon generator and the optical wave-guide.