HAMR Waveguide Pseudo-Slab Stray Light Confinement
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) devices, stray light from the laser diode is not efficiently coupled into the waveguide core, leading to uncontrolled light travel and heating issues, which cause unpredictable changes in the air-bearing surface and affect the accuracy of head positioning during writing and reading.
Innovation Solution
A waveguide system with pseudo-slab regions of higher refractive index than the cladding regions is used to confine and channel stray light away from the near-field transducer, minimizing heating and enhancing coupling efficiency by reshaping the fundamental mode profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a waveguide core is used to guide light from the laser diode, then light coupling efficiency is improved, but stray light is not fully confined leading to uncontrolled light travel and heating issues
Solution Approach 1:
The waveguide structure is segmented into multiple functional regions: a central waveguide core for primary light guidance, surrounded by first and second cladding regions, which are in turn surrounded by first and second pseudo-slab regions. This segmentation creates distinct zones with different refractive indices to manage light propagation and confine stray light effectively.
Solution Approach 2:
The cladding regions and pseudo-slab regions act as intermediary structures between the waveguide core and the surrounding environment. These intermediary layers with progressively lower refractive indices serve to confine and redirect stray light away from the air-bearing surface, preventing harmful heating effects.
2Object-affected harmful factors
If cladding regions are added around the waveguide core, then stray light confinement is improved, but device complexity increases
Solution Approach 1:
The cladding regions and pseudo-slab regions are merged into a unified waveguide structure that integrates multiple functions: light guidance, mode shaping, and stray light confinement. This merging approach achieves effective stray light management without requiring completely separate confinement structures.
Solution Approach 2:
The structure utilizes controlled variations in refractive index parameters across different regions (core, cladding, pseudo-slab) to achieve stray light confinement. By carefully selecting and varying these optical parameters, the patent achieves effective light management while maintaining a relatively simple geometric structure.
3Object-affected harmful factors
If pseudo-slab regions with higher refractive index are added, then stray light confinement is improved, but manufacturing complexity increases
Solution Approach 1:
The patent achieves improved stray light confinement by controlling the refractive index parameter distribution rather than relying on complex geometric arrangements. The pseudo-slab regions have a higher refractive index than the cladding regions, creating an optical potential well that confines and channels stray light. This parameter-based approach simplifies the manufacturing process compared to creating complex geometric structures.
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 pseudo-slab configuration increases coupling efficiency by approximately 7% and reduces uncontrolled light, leading to more precise head positioning and improved data storage accuracy.
Implementation Method 1
The first and second pseudo-slab regions have an index of refraction higher than that of the first and second cladding regions. The first and second pseudo-slab regions confine stray light resulting from coupling of a light source with the waveguide core at the input surface.
Implementation Method 2
The first and second pseudo-slab regions confine stray light resulting from coupling of a light source with the waveguide core at the input surface. The first and second pseudo-slab regions channel the stray light away from the near-field transducer.
Data Source
AI summary
A recording head has a waveguide core with an input facet at an input surface. The waveguide core extends to a near-field transducer at a media-facing surface of the recording head. First and second cladding regions are co-planar with and on either cross-track side of the waveguide core. First and second pseudo-slab regions are co-planar with and on outer cross-track sides of the respective first and second cladding regions. The first and second pseudo-slab regions have an index of refraction higher than that of the first and second cladding regions. The first and second pseudo-slab regions confine and channel stray light away from the near-field transducer.