Gradient Index Waveguide for HAMR Coupling Tolerance
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Solution Overview
Problem
Existing heat-assisted magnetic recording (HAMR) technologies face challenges in maintaining coupling efficiency and assembly tolerance due to stringent alignment requirements between the laser source and the waveguide input coupler, limiting production yield and flexibility.
Innovation Solution
A waveguide with a gradient index material surrounding the input coupler, which has a varying refractive index to compensate for misalignment and improve light coupling efficiency, allowing for increased assembly tolerance by bending light rays and maintaining efficient coupling across different positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stringent alignment requirements are imposed between laser source and waveguide input coupler, then coupling efficiency is improved, but assembly tolerance decreases and production yield is limited
Solution Approach 1:
The patent introduces a gradient index material with continuously varying refractive index (from n1 at the input coupler interface to n2 at the outer boundary, where n1 > n2) to modify the optical path. This parameter change in the refractive index profile enables light rays to be gradually bent and focused toward the waveguide core, compensating for misalignment without requiring precise mechanical alignment, thus resolving the contradiction between coupling efficiency and assembly tolerance
Solution Approach 2:
The gradient index material acts as an intermediary optical element positioned between the input coupler and the waveguide core. It mediates the light transmission by progressively redirecting divergent or misaligned light rays toward the core through its spatially varying refractive index, thereby improving coupling efficiency while relaxing the alignment requirements between the laser source and waveguide
2Manufacturing precision
If precise alignment is required between laser source and waveguide input coupler, then light coupling efficiency is improved, but production yield decreases
Solution Approach 1:
By implementing a gradient index material with a controlled refractive index profile (varying from n1 to n2 across the material thickness), the patent modifies the optical parameters to enable automatic light focusing. This reduces the sensitivity to alignment variations during assembly, allowing for higher production yield without sacrificing coupling efficiency
Solution Approach 2:
The gradient index material serves as a pre-designed optical compensation mechanism that anticipates and corrects for potential misalignments before light enters the waveguide core. By embedding this corrective function in the optical path design rather than relying on precise mechanical alignment, the system cushions against manufacturing variations and improves production yield
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 gradient index material enhances coupling efficiency and increases assembly tolerance by up to 10% in both cross-track and down-track directions, improving the robustness of the laser-to-slider assembly process.
Implementation Method 1
The gradient index material comprises a first refractive index proximate the coupling layer and a second refractive index away from the coupling layer. The gradient index material is configured to direct light from an input facet to the core layer.
Data Source
AI summary
A waveguide a core extending along a light propagation and a coupling layer adjacent one side of the core along the light propagation direction. A gradient index material is adjacent to at least one side of the coupling layer. The gradient index material has a first refractive index proximate the coupling layer and a second refractive index away from the coupling layer. The gradient index material is configured to direct light from an input facet to the core layer.