Waveguide Core Taper for Stray Light Reduction in Write Heads
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Solution Overview
Problem
Existing waveguide designs in write heads suffer from stray light losses, leading to unwanted modulation of the energy source and erasure of magnetic recording media due to inefficient light coupling and reflection issues.
Innovation Solution
The waveguide design incorporates a core with tailored shapes, such as steps or tapers, and dielectric materials with lower refractive indices near the near-field transducer to reduce stray light, enhancing energy redistribution and coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional waveguide design is used, then the structure is simple, but stray light causes unwanted modulation of the energy source and erasure of magnetic recording media
Solution Approach 1:
The waveguide core is designed with non-uniform thickness, being thinner near the near-field transducer and thicker away from it. This local variation in geometry allows the waveguide to control and redirect stray light away from the media, preventing unwanted erasure while maintaining overall structural integrity and functionality.
2Ease of manufacture
If the waveguide core has uniform thickness, then manufacturing is easier, but light coupling efficiency is reduced and stray light increases
Solution Approach 1:
The waveguide core's geometric parameter (thickness) is varied along its length, transitioning from a thinner region near the near-field transducer to a thicker region away from it. This parameter change optimizes light coupling efficiency and reduces stray light, achieving better energy management while remaining manufacturable.
3Strength
If the waveguide core thickness is increased, then mechanical strength is improved, but stray light reflections increase causing media heating
Solution Approach 1:
The waveguide core employs local variation in thickness, maintaining sufficient thickness for mechanical strength in regions away from the transducer while reducing thickness near the near-field transducer to minimize stray light reflections that would otherwise heat the media.
4Object-affected harmful factors
If the waveguide core is made thinner near the near-field transducer, then stray light is reduced, but mechanical strength decreases
Solution Approach 1:
The waveguide core is designed with non-uniform thickness distribution, being thinner near the near-field transducer to reduce stray light while maintaining adequate thickness in other regions to preserve mechanical strength. This localized geometric optimization balances optical performance with structural integrity.
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 reduces stray light reflections and enhances the thermal gradient, leading to improved write head efficiency and reduced media heating, thereby minimizing unwanted erasure and increasing data writing accuracy.
Implementation Method 1
a waveguide having a core with a first side disposed proximate to the near-field transducer. The core overlaps the near-field transducer at a substrate-parallel plane
Implementation Method 2
dielectric materials with lower refractive indices near the near-field transducer to reduce stray light, enhancing energy redistribution
Data Source
AI summary
A write head includes a near-field transducer near a media-facing surface of the write head. The write head includes a waveguide having a core with a first side disposed proximate to the near-field transducer. The core overlaps the near-field transducer at a substrate-parallel plane. The core includes one of a step or a taper on a second side facing away from the first side. The step or the taper causes a reduced thickness of the core normal to the substrate-parallel plane. The write head includes a cladding layer that encompassing the second side of the core and that fills in the step or the taper.